Journal of Consulting and Clinical Psychology 1990, Vol. 58, No. 4, 482-488
Copyright 1990 by the American Psychological Association Inc 0022-006X/90/S00.75
Relative Endurance of Unipolar Depression Treatment Effects: Longitudinal Follow-Up Peter D. McLean
A. Ralph Hakstian
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Department of Psychiatry University of British Columbia
University of British Columbia
This study represents a 2.25-year follow-up to a treatment study reported earlier (McLean & Hakstian, 1979) in which 121 unipolar depressed outpatients were treated by either (a) nondirective psychotherapy, (b) behavior therapy, (c) pharmacotherapy, or (d) relaxation therapy. A nondepressed, normal control group was evaluated on the same 28 measures and 6 intervals for contrast purposes. Behavior therapy patients alone were significantly improved in the areas of mood, personal productivity, and social activity, relative to treatment control patients over the follow-up period. Also, twice as many behavior therapy patients (i.e., 64%) fell within one standard deviation of the normal, nondepressed control group distribution on depressed mood, compared with nondirective psychotherapy and pharmacotherapy patients, when scores were aggregated across the 6 assessment points.
Historically, antidepressant medication has been the treatment of choice for unipolar depression. More recently, psychotherapy has been found to be as effective as standard antidepressant medication in treating unipolar depression (e.g., Klerman & Weissman, 1987) or more effective (for efficacy review see Steinbrueck, Maxwell, & Howard, 1983). Particularly promising are the cognitive-behavioral (C-B) therapies (see Hoberman & Lewinsohn, 1984, for review). The course of depression, however, is generally unfavorable in terms of the chronicity of symptoms and risk of relapse. NystrOm (1979) reported that 67% of depressed patients (primarily endogenous depressions) experienced periods of well-defined depression over a 10-year follow-up period. During the Consensus Development Conference convened by the National Institute of Mental Health/National Institutes of Health (NIMH/NIH; 1985), investigators estimated that 50% of patients with recurrent unipolar disorders relapse within 2 years of recovery from their index episode. This estimate is consistent with the relapse figures reported by Belsher and Costello (1988). These latter reviewers found a relapse rate trend across studies of approximately 20% at 2 months postrecovery, which climbed to 40% within 12 months and became steady at 50% by 2 years postrecovery. There have been few reports that address the important question of durability of treatment effects gained by psychological treatments of depression. Using a meta-analytic approach to evaluate posttherapy adjustment in 28 psychological treatment studies, and with the Beck Depression Inventory (BDI; Beck, Ward, Mendelson, Mock, & Erbaugh, 1961) as the criterion measure, Nietzel, Russell, Hemmings, and Gretter (1987) found posttreatment results to be well maintained at follow-up. The length of follow-up assessment in this review, however, was
relatively short (M = 16.4 weeks, range = 4-52 weeks). Blackburn, Eunson, and Bishop (1986) reported that fewer depressed patients had relapsed during a 2-year follow-up period after receiving cognitive therapy, compared with those who had received pharmacotherapy. Similarly, Teri and Lewinsohn (1986), using the BDI and diagnostic status as outcome measures to evaluate the effects of social-learning treatment for depression, reported that the significant posttreatment effects were maintained at 1- and 6-month follow-up periods in terms of both outcome measures. Taken together, these follow-up results are encouraging, but they raise intriguing methodological and conceptual questions. Patient status in much of the follow-up literature is described retrospectively as either remitted or relapsed. This categorical view of mental disturbance presents a variety of problems for follow-up research. Specification of patient status as simply remitted or relapsed is somewhat arbitrary and has the effect of maximizing the differences between people who are close to either side of the cut point on this classification criterion. Diagnostic or symptom status is usually not detailed in the determination of relapse; the term typically refers to the reinstatement of treatment. Alternatively, the dimensional approach to the conceptualization of depression is not range-restricted and permits both clinical and subclinical evaluation of depression, which more accurately reflects the course of posttreatment adjustment, particularly if assessed frequently. Furthermore, a dimensional assessment strategy has the advantage that other measures of functioning considered relevant to posttreatment adjustment can be assessed, resulting in a more complete picture of patient status than would otherwise be gained through an exclusive focus on patient symptomatology. Another problem in the follow-up research literature concerns the number of assessments made over the course of the follow-up period. Single-point estimates in follow-up studies are problematic in that the course characteristics for depressive
Correspondence concerning this article should be addressed to Peter D. McLean, Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, British Columbia, Canada V6T2A1.
482
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SURVIVAL OF DEPRESSION TREATMENT EFFECTS disorder are highly variable. We take the position that an adequate assessment of disorder course involves sampling patient status on a variety of dimensions frequently over time and that the best estimate of outcome represents an aggregate of these repeated measures. This study represented an attempt to overcome some of these methodological problems during the follow-up of patients who had just completed a 10-week treatment trial of either nondirective psychotherapy, behavior therapy, relaxation therapy, or pharmacotherapy. The purpose of our study was to evaluate the longevity of the treatment effects reported earlier (McLean & Hakstian, 1979). Specific goals were to (a) assess patients at six points over a 27-month follow-up period in order to gain a stable and extended view of posttreatment adjustment, (b) assess patients on a comprehensive set of seven logical outcome dimensions, derived from the reduction of 28 questionnaire variables, and (c) contrast patient status with that of a matched, nondepressed, normal sample. Method For a more detailed description of subject selection, outcome measures, and treatment methods than is presented below, readers should refer to our earlier article (McLean & Hakstian, 1979).
Subject Selection Depressed subjects between 20 and 60 years of age were recruited through newspaper announcements. The diagnosis of unipolar depression was made on the basis of the following 3-stage screening procedure: (a) telephone screening to determine whether functional impairment attributable to depression had been present for at least 1 month; (b) a semi-structured clinical interview with a licensed and experienced clinical psychologist or psychiatrist to determine whether subjects met the diagnostic criteria for psychiatric research in clinical depression suggested by Feighner et al. (1972); and (c) psychometric evaluation. To qualify by the psychometric evaluation, subjects had to be within at least the moderate range for clinical depression on two of three well-known measures(Minnesota Multiphasic Personality Inventory Depression scale a 25 for men and ^29.5 for women, BDI a 23, and Lubin's [1965] Depression Adjective Check List a 14). Subjects were required to be fluent in English and not be simultaneously receiving treatment for depression elsewhere. Of 541 subjects screened for depression, 196 were admitted to the study. Only those subjects (N = 121) for whom data were available at all six posttreatment assessment points were included in this study. Nondepressed subjects were recruited through newspaperannouncements inviting participation in a life-styles program and were matched by age and gender to the depressed subject sample. Nondepressed subjects were admitted to the study if (a) symptoms of depression were absent during clinical interview and a history of depressive episodes was denied, (b) subjects had never received professional help for any mental health problem, and (c) subjects scored below the criteria necessary for depressed subjects to gain entry to the study, on all three of the depression measures noted above. This screening procedure yielded 55 nondepressed subjects.
Design Depressed subjects were randomly assigned to one of four treatment conditions: (a) psychotherapy, (b) relaxation training, (c) behavior ther-
483
apy, and (d) drug therapy. Depressed and nondepressed subjects were reevaluated upon completion of the fixed treatment term by means of a mail-return questionnaire package. This evaluation was done at six points over a 27-month follow-up period (a) immediately posttreatment, and (b) 3 months, (c) 9 months, (d) 15 months, (e) 21 months, and (f) 27 months posttreatment. Subjects were paid between $5 and $15 on an incremental basis over the follow-up period for completing each questionnaire package.
Treatments All treatments were delivered on an individual outpatient basis in the form of 10 weekly visits by licensed and experienced psychologists, physicians, or psychiatrists. Therapists were selected on the basis of their reputations in the particular modality/school of treatment they offered, with the exception of the treatment control condition, relaxation therapy. Each treatment session lasted 1 hr for the three verbal treatments and Vi hr for the drug treatment condition. Readers interested in details on the steps taken to reduce treatment heterogeneity among therapists within the treatment conditions, and in more information in general about treatments than is provided below, are referred to our earlier article (McLean & Hakstian, 1979). A brief description of the four treatment procedures follows. Nondirective psychotherapy. Therapists used fundamental principles of insight-oriented, nondirective psychodynamic therapy to guide treatment. Attention was directed to patients' perceptual and symbolic distortions and to the recognition of personality problems as they related to past experiences and the current depression. Relaxation therapy. This treatment is not normally used as an exclusive treatment for depression and was expected to be only minimally effective. It was used as a treatment control condition. As anxiety and depression are often correlated, anxiety reduction by means of relaxation training may have indirectly ameliorated depression, but it was not expected to have a direct and significant therapeutic effect on depression. Patients were taught that there is a relation between muscle tension and depression, and they participated in a highly structured relaxation training program, which included 25 min of home practice, 6 days per week. Symptomatic complaints of depression that arose during the course of treatment were reinterpreted in terms of muscle tension. Behavior therapy. The rationale offered patients in this treatment condition was that the experience of depression was the inevitable result of ineffective coping techniques applied to situational life problems. Treatment methods utilized graduated practice, modeling techniques, and daily homework assignments. Particular emphasis was placed on the development of prosocial behavior and the preparation for coping successfully with future depressive episodes. Drug therapy. Patients in this condition were given a biochemical rationale to explain the occurrence of their depression. Patients were treated with Amitriptyline for 11 weeks at 150 mg/day. Patients completed a side effects questionnaire and a physiological review (e.g., blood pressure, weight, pulse rate and rhythm, etc.) with their project physician.
Measures Both depressed and nondepressed control subjects were assessed on 28 questionnaire variables during each of the six posttreatment followup points. Seventeen of the 28 variables were single-item frequency measures for events that had occurred within the previous 2-7 days. Ten variables constituted single-scale estimates that referred to the same time interval. One variable consisted of the Depression Adjective Check List (Lubin, 1965).
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484
PETER D. MCLEAN AND A. RALPH HAKSTIAN
The 28 items in the depression questionnaire were used to generate seven logical dimensions: (a) cognitive, (b) coping, (c) personal activity, (d) social, (e) somatic indicators, (f) overall general satisfaction, and (g) mood. It was felt that these questionnaire variables tapped important dimensions of functioning that were often absent or underrepresented in conventional depression questionnaires and that their inclusion represented a more comprehensive evaluation of individual functioning. The 28 items were categorized logically into the above seven dimension classes. Within each logical dimension except the satisfaction dimension, responses by the depressed subjects to the questionnaire items administered at the pretreatment period were intercorrelated, and the first principal component was obtained. Because of its psychometric advantages, this derived variable was seen as preferable to a simple average of the constituent variables within a dimension. These six principal components (one for each dimension except satisfaction) were scaled to have a mean of 50 and standard deviation of 10 across all depressed subjects at pretreatment. Thus, principal components analysis was used here not to structure the 28 questionnaire variables (they were already logically structured into seven categories), but rather to obtain for each category a single summary random variable with optimal psychometric properties. (In the case of the satisfaction dimension, the three constituent variables were simply averaged, because for these items there were many missing responses.) For all subsequent measurement points (i.e., the six posttreatment evaluation points), raw item scores, within dimension, were referenced to the pretreatment item means, the principal component weights for the dimension were applied, and the resulting linear combination was multiplied by 10 and added to 50. This practice, followed for both the depressed and nondepressed subjects, set the pretreatment levels as a reference point and allowed the means to shift over the course of therapy and follow-up, features that would not have been present had the raw item data been standardized at each evaluation point relative to that point's item means. In order to assess changes over time, as well as those occurring between treatment groups, this procedure was necessary. Again, for the satisfaction dimension, constituent item scores were simply averaged at each evaluation point. The method of data reduction described above (i.e., generation of principal components) was used to obtain comprehensive and stable measures of salient dimensions of functioning, which, in turn, were based primarily on frequency of recent events. In order to reduce redundancy with our earlier article (McLean & Hakstian, 1979), we give no further detail here on the logical dimensions, the questionnaire variables, and the relations among these entities. Interested readers are referred to Table 1 of that earlier article for greater detail on these matters.
Analysis Procedures The first analysis conducted in the study was a 4 (treatment group) X 6 (time period)fixed-effects,between-within groups multivariate analysis of covariance (MANCOVA), with the seven dependent variables: the cognitive, coping, personal activity, social, somatic indicators, average satisfaction, and mood derived variables discussed earlier (measured at each time interval). The pretreatment scores on these seven derived variables were used as the covariate set for this analysis. Only those subjects for whom results at all six time points were available were included in this and the subsequent analyses. These group ns were Group 1 (psychotherapy), 28; Group 2 (relaxation therapy), 35; Group 3 (C-B therapy), 33; Group 4 (drug therapy), 25; for a total iVof 121. This slight imbalance in group sample sizes presented no data-analytic problems, as cell-size proportionality was, of course, preserved, and the necessary unequal-^ adjustments were made where required in the
follow-up analyses. The main purpose in beginning the analyses with this MANCOVA was to use it as protection against an excessive experimentwise Type I error rate that would be present with a series of univariate analyses of covariance (ANCOVAS) not accompanied by some form of error protection. Such a multivariate comparative analysis conducted at the alpha level of significance, followed, only if significant, by follow-up univariate comparative analyses also conducted at the alpha level, ensures an experimentwise (or familywise) Type I error rate of alpha. Because the MANCOVA described above yielded significant results, univariate ANCOVAS were conducted on each dependent variable in turn. These were 4 X 6fixed-effects,between-within groups ANCOVAS with the pretreatment scores corresponding to the particular dependent variable covaried in each case. The slight departure from cell-size equality rendered homogeneity of variance and regression assumptions irrelevant to the tests on the Treatment factor (see Glass, Peckham, & Sanders, 1972). Violation of sphericity assumptions in connection with the Time and interaction effects was dealt with using Huynh and Feldt's (1976) recommendations (and reductions in degrees of freedom). For dependent variables yielding significant between-groups main effects, follow-up multiple comparisons were conducted using the generalized studentized range statistic (see Kirk, 1982, p. 736), with the necessary adjustments for the covariates made by the Bryant and Paulson (1976) procedure. The adjustment for the slightly unequaln pattern was made by the Spjotv011 and Stoline (1973) procedure. Finally, in an attempt to make more concrete the between-groups results, a series of inferential analyses of percentages was carried out for the significant (by the ANCOVAS) dependent variables, in which the percentages in each group exceeding a particular point in the score distributions for the normal, nondepressed subjects were compared. These latter analyses are described in more detail in the Results section.
Results Table 1 presents the group means of the seven outcome measures aggregated over six time points for each of the four treatment groups and, for purposes of comparison, the nondepressed control group. The results of the analyses are presented in the order they were covered earlier.
Overall MANCOVA The results of this initial 4 x 6 multivariate analysis of the seven dependent variables were as follows: Group effect: A = .737, F(2\, 299) = 1.60, p < .05; time effect: A = .454, F(35, 83) = 2.85, p < .001; Group X Time interaction effect: A = .341, F(105, 249) = 1.03, p > .25. Thus, furthermore finely graded analyses were warranted.
Univariate ANCOVAS Results of the univariate ANCOVAS conducted on the seven outcome variables in turn, along with results of the follow-up multiple comparisons, appear in Table 2. First, it can be seen from Table 2 that a significant Time effect was obtained in the analyses of the personal activity and social dependent variables. Because, however, no systematic and easily interpretable trend was found in the pattern of the adjusted means over the six time points in each case, no followup analyses were conducted, and no interpretation will be at-
SURVIVAL OF DEPRESSION TREATMENT EFFECTS
485
Table 1 Group Means of Seven Outcome Measures Obtained at Six Time Points Normal subjects
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Treatment group 2 Relaxation therapy («=35)
3 Behavior therapy
Dependent variable
1 Psychotherapy Oi=28)
Cognitive" Coping* Personal activity* Social* Somatic indicators* Average satisfaction Mood*
65.41 65.11 53.33 59.33 59.78 3.10 67.05
63.30 60.88 53.02 56.36 59.11 3.30 65.35
66.60 65.63 57.76 64.91 63.56 2.66 72.19
4 Drug therapy (»-25)
M
SD
65.09 64.76 56.97 59.31 61.20 2.63 67.59
74.42 71.72 55.32 66.92 70.47 1.89 78.17
6.26 6.99 8.55 10.89 8.42 1.07 7.96
(n = 45)
Note. Treatment group means are adjusted means (for the effect of the covariate, pretreatment scores on the same variable, used in the subsequent comparative analyses). These analyses involved only subjects from the four treatment groups; means for normal subjects (not adjusted) are presented for comparative purposes only. * Variables for which a high score is favorable, or less indicative of depression. Average satisfaction is scaled so that a low score is favorable.
tempted of these effects. Second, it is clear from Table 2 that for none of the seven outcome variables was the Treatment Group factor found to interact with the Time factor. Our interest, therefore, is in the Treatment Group main effects found to be significant. As seen in Table 2, three of the seven outcome variables yielded such an effect: the personal activity, social, and mood variables. For each of these, follow-up pairwise multiple comparisons were conducted, yielding the results in the far right column of Table 2. Here we see that for each dependent variable, the Group 3 (behavior therapy) mean was highest, differing significantly from the Group 2 (relaxation therapy) mean in each case and, for the personal activity dependent variable, from the psychotherapy group mean as well.
Thus, the pattern seen in our earlier study (McLean & Hakstian, 1979)—in the analyses of both immediate posttreatment results as well as 3-month follow-up results—was replicated. Behavior therapy means were highest on both the social and mood dependent variables in the present analyses involving means aggregated over a 2.25-year follow-up period. The present finding regarding the personal activity outcome over the 2.25-year follow-up period, however (i.e, in which the behavior therapy mean was significantly higher than both the psychotherapy and relaxation therapy means), was not obtained in the earlier analyses of immediate posttreatment and 3-month follow-up results, and thus it represents something of a sleeper effect. The trend of disproportionate dropout found during the
Table 2 Results ofUnivariate Analyses ofCovariance of Seven Outcome Measures at Six Time Points F ratios for effects'
Dependent variable
MS, for treatment (df=\\6)
Treatment F
MS, for time and interaction11
Time F
Interaction F
Significant pairwise multiple comparisons'
Cognitive Coping Personal activity Social Somatic indicators Average satisfaction Mood
436.23 381.17 279.51 532.38 539.39 10.16 608.04
0.85 2.50* 3.99** 4.78** 1.39 2.03 2.79*
75.61 80.73 73.89 104.59 1 10.23 1.47 121.05
1.61 1.47 2.71* 2.34* 1.66 2.15* 1.74
0.20 0.44 1.05 1.56* 0.63 1.09 1.05
None None 3 vs. 1;3 vs. 2 3 vs. 2 None None 3 vs. 2
Note. For each dependent variable analyzed, the pretreatment scores on the same variable were used as covariate. * MSs for effects are reproducible by F (for effect) x MS (used to test that effect). b The dffor Time and for Treatment X Time interaction effects varied depending on the necessary adjustment for nonsphericity. 0 These multiple comparisons were conducted by the generalized studentized range statistic and were performed after a significant Treatment main effect on the marginal treatment group means. *p .75. Thus there was no evidence whatsoever of differential rates of additional treatment between the treatment groups.
Alternative Analysis of Treatment Groups Finally, an attempt was made to represent some of the parametric results given in Table 1 in somewhat different form. We calculated the percentages of subjects in each of the treatment groups whose unadjusted, aggregated (over the six time periods) subject means lay above a point in the normal, nondepressed group distribution (aggregated in a similar fashion) that was one standard deviation below the normal group mean. (We note here that of the original 55 nondepressed subjects, complete data at all time points were available on 45, and it is this subset that was used in the present calculations and is represented in Table 1.) Although admittedly somewhat arbitrary, this point was chosen as representing a reasonable upper region (upper 84% in a normal distribution) of nondepressed scores on the relevant dependent variables (i.e., those on which significance had been attained in the earlier analyses: the personal activity, social, and mood variables). Inferential comparative tests on these four (treatment group) percentages were then conducted for each dependent variable in turn, using procedures described by Marascuilo (1966). For the personal activity and social variables, these analyses yielded nonsignificant results, but for the mood dependent variable, the analysis of the four percentages (psychotherapy, 35.7%; relaxation therapy, 25.7%; behavior therapy, 63.6%; and drug therapy, 28.0%) yielded a statistically significant result, x2(3, N=l2l) = 13.48, p < .01. Follow-up multiple comparisons were performed (with alpha set to .05), and the behavior therapy group percentage was found to be significantly higher than the percentages for the relaxation therapy and drug therapy groups in turn (no other pairwise contrasts were significant) and from the aggregated
APA-Con Clin Psvch
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percentage of the other three groups. These results are summarized in Table 3. The results in Table 3 parallel, of course, those in Table 2, at least to some extent. A majority of behavior therapy subjects (63.6%) had posttreatment aggregated means (over the six time points extending 2.25 years posttreatment) that were within the upper range of the normal, nondepressed distribution of parallel aggregated means. This finding suggests that, over this follow-up period, the mood variable scores of the behavior therapy subjects were roughly parallel to those of the normal subjects. This result was not found, however, for the subjects in the other three treatment groups.
Discussion Our primary finding was that exposure to behavior therapy (10 hr) had a prophylactic influence over a 2.25-year posttreatment follow-up period for depressed patients, relative to a treatment control condition, whereas other therapies did not. Specifically, over the 27-month follow-up period, behavior therapy patients were significantly improved in mood, more socially active, and more personally productive, compared with treatment control group patients. Psychotherapy and pharmacotherapy patients were not distinguished from treatment control patients during the follow-up period on any outcome measure. The detection of treatment group differences was largely due to the inclusion of a treatment control condition (relaxation therapy), which contrasted most strongly with the behavior therapy group; the psychotherapy and pharmacotherapy groups assumed intermediate positions on most outcome measures. As seen in Table 1, the behavior therapy group was strongest, over the 27-month period, on six of seven outcome measures, although for only three of these were the differences statistically significant. In contrast, the pharmacological group performed best on one of six measures, and the psychotherapy group on zero of six measures. It is possible that behavior therapy patients fared better over the course of follow-up due to the directive nature of their therapy experience, which encouraged adaptive problem solving, social involvement, practical goal attainment, and new ways of interpreting and tolerating emotional distress. Also, behavior therapy patients were taught to expect, and were prepared for, relapse challenges. It should be noted that the behavioral treatment in this study consisted of both cognitive and behavioral elements sufficiently intermixed that attribution of outcome as a function of treatment element (i.e, cognitive vs. behavioral) was not possible. In any case, Rehm, Kaslow, and Rabin (1987) found that self-control therapy for depression was effective regardless of whether cognitive or behavioral treatment targets were pursued, and it appears that cognitive and behavioral prescriptions are common in both cognitive and behavioral treatments regardless of title. Following Kazdin's (1982) suggestion to make normative comparisons by contrasting client status with that of nondisturbed, normal peers, and in line with the recommendation of Jacobson, Follette, and Revenstorf (1984) to report psychotherapy outcome results in ways other than group treatment means,
Fri Jul 13 22:40:38 1990
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SURVIVAL OF DEPRESSION TREATMENT EFFECTS
Table 3 Percentages of Subjects by Group With an Aggregated Mean on the Mood Variable in the Upper Region of the Normal Group Score Distribution and Significance Test Results
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Treatment group
2
3
4
Relaxation therapy
Behavior therapy
Drug therapy
Subjects
1 Psychotherapy
n
28
35
33
25
% in specified region
35.7
25.7
63.6
28.0
Significant multiple comparisons* 3 vs. 2; 3 vs. 4 3 vs. (1,2, 4)
Note. The region of interest in the nondepressed score distribution is that part of the distribution occurring above one standard deviation below the mean. • Overall test: X2(3) = 13.48, p < .01.
we found, in this study, that approximately twice as many patients from the behavior therapy condition (i.e., 63.4%) fell within one standard deviation of the mean of the normal, nondepressed group distribution on depressed mood (aggregated across all six assessment points), compared with patients from the other treatment groups. In summarizing the treatment and follow-up results, the behavior therapy condition resulted in significantly fewer treatment dropouts during the course of treatment, posted the best immediate treatment results, and was the only treatment group to be distinguished from the treatment control condition during follow-up. The maintenance of improvement on several key outcome variables over a 2.25-year follow-up of unipolar depressed patients, after a relatively brief treatment exposure of 10 hr, has important implications for the development of prevention strategies. Our study had a number of methodological strong points. It represents the 'first depression treatment study to use a treatment control condition and a nondepressed, normal contrast group through both treatment and follow-up. Additionally, the relatively large number of subjects probably lent statistical power to the detection of group differences that may have eluded smaller studies (Nietzel et al, 1987), and the use of six posttreatment assessment points served to provide a more representative sample of patient adjustment over follow-up than is normally reported. Finally, this study used a multidimensional assessment strategy in an attempt to evaluate more comprehensively the range of symptom and personal adjustment areas considered relevant to depression: seven dimensions, each derived from a number of questionnaire responses. A limitation of our study stems from the absence of diagnostic classification at selected intervals over the follow-up period. Had such diagnostic information been obtained, it would have permitted comparability between studies and might have permitted outcome prediction. Gonzales, Lewinsohn, and Clarke (1985), for example, found the recovery rate for treated depressives to be significantly different, depending on whether the diagnosis was major depressive disorder, intermittent depressive disorder, or superimposed depressive disorder, according to Research Diagnostic Criteria (Spitzer, Endicott, & Robins, 1978). Despite this limitation, our study showed that the benefits of cognitive-behavioral therapy for the treatment of unipo-
lar depression were superior to those of both nondirective psychotherapy and pharmacotherapy when delivered alone and were enduring over time.
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PETER D. MCLEAN AND A. RALPH HAKSTIAN
(IPX) and drugs in the treatment of depression. Pharmacopsychiatry, 20, 3-7. Lubin, B. (1965). Adjective checklists for measurement of depression. Archives of General Psychiatry, 12, 57-62. Marascuilo, L. A. (1966). Large-sample multiple comparisons. Psychological Bulletin, 65, 280-290. McLean, P. D., & Hakstian, A. R. (1979). Clinical depression: Comparative efficacy of outpatient treatments. Journal of Consulting and Clinical Psychology, 47, 818-836. Nietzel, M. T, Russell, R. L, Hemmings, K. A, & Gretter, M. L. (1987). Clinical significance of psychotherapy for unipolar depression: A meta-analytic approach to social comparison. Journal of Consulting and Clinical Psychology, 55,156-161. National Institute of Mental Health/National Institutes of Health (NIMH/NIH) Consensus Development Conference Statement. (1985). Mood disorders: Pharmacological prevention of recurrences. American Journal of Psychiatry, 142, 469-476. Nystrbm, S. (1979). Depressions: Factors related to 10-year prognosis. Ada Psychiatrica Scandinavica, 60, 225-238. Rehm, L. P., Kaslow, N. J, & Rabin, A. S. (1987). Cognitive and behav-
ioral targets in a self-control therapy program for depression. Journal of Consulting and Clinical Psychology, 55, 60-67. Spitzer, R. L., Endicott, J, & Robins, E. (1978). Research diagnostic criteria: Rationale and reliability. Archives of General Psychiatry, 35, 773-782. Spjotvell, E., & Stoline, M. R. (1973). An extension of the T-method of multiple comparisons to include the cases with unequal sample sizes. Journal of the American Statistical Association, 68, 975-978. Steinbrueck, S. M., Maxwell, S. E, & Howard, G. S. (1983). A meta-analysis of psychotherapy and drug therapy in the treatment of unipolar depression with adults. Journal of Consulting andClinical Psychology, 51, 856-863. Teri, L., & Lewinsohn, P. M. (1986). Individual and group treatment of unipolar depression: Comparison of treatment outcome and identification of predictors of successful treatment outcome. Behavior Therapy, 77,215-228. Received Aprill 3,1989 Revision received November 3,1989 Accepted December 26,1989 •
Copyright 1990 by the American Psychological Association Inc 0022-006X/90/S00.75
Relative Endurance of Unipolar Depression Treatment Effects: Longitudinal Follow-Up Peter D. McLean
A. Ralph Hakstian
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Department of Psychiatry University of British Columbia
University of British Columbia
This study represents a 2.25-year follow-up to a treatment study reported earlier (McLean & Hakstian, 1979) in which 121 unipolar depressed outpatients were treated by either (a) nondirective psychotherapy, (b) behavior therapy, (c) pharmacotherapy, or (d) relaxation therapy. A nondepressed, normal control group was evaluated on the same 28 measures and 6 intervals for contrast purposes. Behavior therapy patients alone were significantly improved in the areas of mood, personal productivity, and social activity, relative to treatment control patients over the follow-up period. Also, twice as many behavior therapy patients (i.e., 64%) fell within one standard deviation of the normal, nondepressed control group distribution on depressed mood, compared with nondirective psychotherapy and pharmacotherapy patients, when scores were aggregated across the 6 assessment points.
Historically, antidepressant medication has been the treatment of choice for unipolar depression. More recently, psychotherapy has been found to be as effective as standard antidepressant medication in treating unipolar depression (e.g., Klerman & Weissman, 1987) or more effective (for efficacy review see Steinbrueck, Maxwell, & Howard, 1983). Particularly promising are the cognitive-behavioral (C-B) therapies (see Hoberman & Lewinsohn, 1984, for review). The course of depression, however, is generally unfavorable in terms of the chronicity of symptoms and risk of relapse. NystrOm (1979) reported that 67% of depressed patients (primarily endogenous depressions) experienced periods of well-defined depression over a 10-year follow-up period. During the Consensus Development Conference convened by the National Institute of Mental Health/National Institutes of Health (NIMH/NIH; 1985), investigators estimated that 50% of patients with recurrent unipolar disorders relapse within 2 years of recovery from their index episode. This estimate is consistent with the relapse figures reported by Belsher and Costello (1988). These latter reviewers found a relapse rate trend across studies of approximately 20% at 2 months postrecovery, which climbed to 40% within 12 months and became steady at 50% by 2 years postrecovery. There have been few reports that address the important question of durability of treatment effects gained by psychological treatments of depression. Using a meta-analytic approach to evaluate posttherapy adjustment in 28 psychological treatment studies, and with the Beck Depression Inventory (BDI; Beck, Ward, Mendelson, Mock, & Erbaugh, 1961) as the criterion measure, Nietzel, Russell, Hemmings, and Gretter (1987) found posttreatment results to be well maintained at follow-up. The length of follow-up assessment in this review, however, was
relatively short (M = 16.4 weeks, range = 4-52 weeks). Blackburn, Eunson, and Bishop (1986) reported that fewer depressed patients had relapsed during a 2-year follow-up period after receiving cognitive therapy, compared with those who had received pharmacotherapy. Similarly, Teri and Lewinsohn (1986), using the BDI and diagnostic status as outcome measures to evaluate the effects of social-learning treatment for depression, reported that the significant posttreatment effects were maintained at 1- and 6-month follow-up periods in terms of both outcome measures. Taken together, these follow-up results are encouraging, but they raise intriguing methodological and conceptual questions. Patient status in much of the follow-up literature is described retrospectively as either remitted or relapsed. This categorical view of mental disturbance presents a variety of problems for follow-up research. Specification of patient status as simply remitted or relapsed is somewhat arbitrary and has the effect of maximizing the differences between people who are close to either side of the cut point on this classification criterion. Diagnostic or symptom status is usually not detailed in the determination of relapse; the term typically refers to the reinstatement of treatment. Alternatively, the dimensional approach to the conceptualization of depression is not range-restricted and permits both clinical and subclinical evaluation of depression, which more accurately reflects the course of posttreatment adjustment, particularly if assessed frequently. Furthermore, a dimensional assessment strategy has the advantage that other measures of functioning considered relevant to posttreatment adjustment can be assessed, resulting in a more complete picture of patient status than would otherwise be gained through an exclusive focus on patient symptomatology. Another problem in the follow-up research literature concerns the number of assessments made over the course of the follow-up period. Single-point estimates in follow-up studies are problematic in that the course characteristics for depressive
Correspondence concerning this article should be addressed to Peter D. McLean, Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, British Columbia, Canada V6T2A1.
482
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SURVIVAL OF DEPRESSION TREATMENT EFFECTS disorder are highly variable. We take the position that an adequate assessment of disorder course involves sampling patient status on a variety of dimensions frequently over time and that the best estimate of outcome represents an aggregate of these repeated measures. This study represented an attempt to overcome some of these methodological problems during the follow-up of patients who had just completed a 10-week treatment trial of either nondirective psychotherapy, behavior therapy, relaxation therapy, or pharmacotherapy. The purpose of our study was to evaluate the longevity of the treatment effects reported earlier (McLean & Hakstian, 1979). Specific goals were to (a) assess patients at six points over a 27-month follow-up period in order to gain a stable and extended view of posttreatment adjustment, (b) assess patients on a comprehensive set of seven logical outcome dimensions, derived from the reduction of 28 questionnaire variables, and (c) contrast patient status with that of a matched, nondepressed, normal sample. Method For a more detailed description of subject selection, outcome measures, and treatment methods than is presented below, readers should refer to our earlier article (McLean & Hakstian, 1979).
Subject Selection Depressed subjects between 20 and 60 years of age were recruited through newspaper announcements. The diagnosis of unipolar depression was made on the basis of the following 3-stage screening procedure: (a) telephone screening to determine whether functional impairment attributable to depression had been present for at least 1 month; (b) a semi-structured clinical interview with a licensed and experienced clinical psychologist or psychiatrist to determine whether subjects met the diagnostic criteria for psychiatric research in clinical depression suggested by Feighner et al. (1972); and (c) psychometric evaluation. To qualify by the psychometric evaluation, subjects had to be within at least the moderate range for clinical depression on two of three well-known measures(Minnesota Multiphasic Personality Inventory Depression scale a 25 for men and ^29.5 for women, BDI a 23, and Lubin's [1965] Depression Adjective Check List a 14). Subjects were required to be fluent in English and not be simultaneously receiving treatment for depression elsewhere. Of 541 subjects screened for depression, 196 were admitted to the study. Only those subjects (N = 121) for whom data were available at all six posttreatment assessment points were included in this study. Nondepressed subjects were recruited through newspaperannouncements inviting participation in a life-styles program and were matched by age and gender to the depressed subject sample. Nondepressed subjects were admitted to the study if (a) symptoms of depression were absent during clinical interview and a history of depressive episodes was denied, (b) subjects had never received professional help for any mental health problem, and (c) subjects scored below the criteria necessary for depressed subjects to gain entry to the study, on all three of the depression measures noted above. This screening procedure yielded 55 nondepressed subjects.
Design Depressed subjects were randomly assigned to one of four treatment conditions: (a) psychotherapy, (b) relaxation training, (c) behavior ther-
483
apy, and (d) drug therapy. Depressed and nondepressed subjects were reevaluated upon completion of the fixed treatment term by means of a mail-return questionnaire package. This evaluation was done at six points over a 27-month follow-up period (a) immediately posttreatment, and (b) 3 months, (c) 9 months, (d) 15 months, (e) 21 months, and (f) 27 months posttreatment. Subjects were paid between $5 and $15 on an incremental basis over the follow-up period for completing each questionnaire package.
Treatments All treatments were delivered on an individual outpatient basis in the form of 10 weekly visits by licensed and experienced psychologists, physicians, or psychiatrists. Therapists were selected on the basis of their reputations in the particular modality/school of treatment they offered, with the exception of the treatment control condition, relaxation therapy. Each treatment session lasted 1 hr for the three verbal treatments and Vi hr for the drug treatment condition. Readers interested in details on the steps taken to reduce treatment heterogeneity among therapists within the treatment conditions, and in more information in general about treatments than is provided below, are referred to our earlier article (McLean & Hakstian, 1979). A brief description of the four treatment procedures follows. Nondirective psychotherapy. Therapists used fundamental principles of insight-oriented, nondirective psychodynamic therapy to guide treatment. Attention was directed to patients' perceptual and symbolic distortions and to the recognition of personality problems as they related to past experiences and the current depression. Relaxation therapy. This treatment is not normally used as an exclusive treatment for depression and was expected to be only minimally effective. It was used as a treatment control condition. As anxiety and depression are often correlated, anxiety reduction by means of relaxation training may have indirectly ameliorated depression, but it was not expected to have a direct and significant therapeutic effect on depression. Patients were taught that there is a relation between muscle tension and depression, and they participated in a highly structured relaxation training program, which included 25 min of home practice, 6 days per week. Symptomatic complaints of depression that arose during the course of treatment were reinterpreted in terms of muscle tension. Behavior therapy. The rationale offered patients in this treatment condition was that the experience of depression was the inevitable result of ineffective coping techniques applied to situational life problems. Treatment methods utilized graduated practice, modeling techniques, and daily homework assignments. Particular emphasis was placed on the development of prosocial behavior and the preparation for coping successfully with future depressive episodes. Drug therapy. Patients in this condition were given a biochemical rationale to explain the occurrence of their depression. Patients were treated with Amitriptyline for 11 weeks at 150 mg/day. Patients completed a side effects questionnaire and a physiological review (e.g., blood pressure, weight, pulse rate and rhythm, etc.) with their project physician.
Measures Both depressed and nondepressed control subjects were assessed on 28 questionnaire variables during each of the six posttreatment followup points. Seventeen of the 28 variables were single-item frequency measures for events that had occurred within the previous 2-7 days. Ten variables constituted single-scale estimates that referred to the same time interval. One variable consisted of the Depression Adjective Check List (Lubin, 1965).
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484
PETER D. MCLEAN AND A. RALPH HAKSTIAN
The 28 items in the depression questionnaire were used to generate seven logical dimensions: (a) cognitive, (b) coping, (c) personal activity, (d) social, (e) somatic indicators, (f) overall general satisfaction, and (g) mood. It was felt that these questionnaire variables tapped important dimensions of functioning that were often absent or underrepresented in conventional depression questionnaires and that their inclusion represented a more comprehensive evaluation of individual functioning. The 28 items were categorized logically into the above seven dimension classes. Within each logical dimension except the satisfaction dimension, responses by the depressed subjects to the questionnaire items administered at the pretreatment period were intercorrelated, and the first principal component was obtained. Because of its psychometric advantages, this derived variable was seen as preferable to a simple average of the constituent variables within a dimension. These six principal components (one for each dimension except satisfaction) were scaled to have a mean of 50 and standard deviation of 10 across all depressed subjects at pretreatment. Thus, principal components analysis was used here not to structure the 28 questionnaire variables (they were already logically structured into seven categories), but rather to obtain for each category a single summary random variable with optimal psychometric properties. (In the case of the satisfaction dimension, the three constituent variables were simply averaged, because for these items there were many missing responses.) For all subsequent measurement points (i.e., the six posttreatment evaluation points), raw item scores, within dimension, were referenced to the pretreatment item means, the principal component weights for the dimension were applied, and the resulting linear combination was multiplied by 10 and added to 50. This practice, followed for both the depressed and nondepressed subjects, set the pretreatment levels as a reference point and allowed the means to shift over the course of therapy and follow-up, features that would not have been present had the raw item data been standardized at each evaluation point relative to that point's item means. In order to assess changes over time, as well as those occurring between treatment groups, this procedure was necessary. Again, for the satisfaction dimension, constituent item scores were simply averaged at each evaluation point. The method of data reduction described above (i.e., generation of principal components) was used to obtain comprehensive and stable measures of salient dimensions of functioning, which, in turn, were based primarily on frequency of recent events. In order to reduce redundancy with our earlier article (McLean & Hakstian, 1979), we give no further detail here on the logical dimensions, the questionnaire variables, and the relations among these entities. Interested readers are referred to Table 1 of that earlier article for greater detail on these matters.
Analysis Procedures The first analysis conducted in the study was a 4 (treatment group) X 6 (time period)fixed-effects,between-within groups multivariate analysis of covariance (MANCOVA), with the seven dependent variables: the cognitive, coping, personal activity, social, somatic indicators, average satisfaction, and mood derived variables discussed earlier (measured at each time interval). The pretreatment scores on these seven derived variables were used as the covariate set for this analysis. Only those subjects for whom results at all six time points were available were included in this and the subsequent analyses. These group ns were Group 1 (psychotherapy), 28; Group 2 (relaxation therapy), 35; Group 3 (C-B therapy), 33; Group 4 (drug therapy), 25; for a total iVof 121. This slight imbalance in group sample sizes presented no data-analytic problems, as cell-size proportionality was, of course, preserved, and the necessary unequal-^ adjustments were made where required in the
follow-up analyses. The main purpose in beginning the analyses with this MANCOVA was to use it as protection against an excessive experimentwise Type I error rate that would be present with a series of univariate analyses of covariance (ANCOVAS) not accompanied by some form of error protection. Such a multivariate comparative analysis conducted at the alpha level of significance, followed, only if significant, by follow-up univariate comparative analyses also conducted at the alpha level, ensures an experimentwise (or familywise) Type I error rate of alpha. Because the MANCOVA described above yielded significant results, univariate ANCOVAS were conducted on each dependent variable in turn. These were 4 X 6fixed-effects,between-within groups ANCOVAS with the pretreatment scores corresponding to the particular dependent variable covaried in each case. The slight departure from cell-size equality rendered homogeneity of variance and regression assumptions irrelevant to the tests on the Treatment factor (see Glass, Peckham, & Sanders, 1972). Violation of sphericity assumptions in connection with the Time and interaction effects was dealt with using Huynh and Feldt's (1976) recommendations (and reductions in degrees of freedom). For dependent variables yielding significant between-groups main effects, follow-up multiple comparisons were conducted using the generalized studentized range statistic (see Kirk, 1982, p. 736), with the necessary adjustments for the covariates made by the Bryant and Paulson (1976) procedure. The adjustment for the slightly unequaln pattern was made by the Spjotv011 and Stoline (1973) procedure. Finally, in an attempt to make more concrete the between-groups results, a series of inferential analyses of percentages was carried out for the significant (by the ANCOVAS) dependent variables, in which the percentages in each group exceeding a particular point in the score distributions for the normal, nondepressed subjects were compared. These latter analyses are described in more detail in the Results section.
Results Table 1 presents the group means of the seven outcome measures aggregated over six time points for each of the four treatment groups and, for purposes of comparison, the nondepressed control group. The results of the analyses are presented in the order they were covered earlier.
Overall MANCOVA The results of this initial 4 x 6 multivariate analysis of the seven dependent variables were as follows: Group effect: A = .737, F(2\, 299) = 1.60, p < .05; time effect: A = .454, F(35, 83) = 2.85, p < .001; Group X Time interaction effect: A = .341, F(105, 249) = 1.03, p > .25. Thus, furthermore finely graded analyses were warranted.
Univariate ANCOVAS Results of the univariate ANCOVAS conducted on the seven outcome variables in turn, along with results of the follow-up multiple comparisons, appear in Table 2. First, it can be seen from Table 2 that a significant Time effect was obtained in the analyses of the personal activity and social dependent variables. Because, however, no systematic and easily interpretable trend was found in the pattern of the adjusted means over the six time points in each case, no followup analyses were conducted, and no interpretation will be at-
SURVIVAL OF DEPRESSION TREATMENT EFFECTS
485
Table 1 Group Means of Seven Outcome Measures Obtained at Six Time Points Normal subjects
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Treatment group 2 Relaxation therapy («=35)
3 Behavior therapy
Dependent variable
1 Psychotherapy Oi=28)
Cognitive" Coping* Personal activity* Social* Somatic indicators* Average satisfaction Mood*
65.41 65.11 53.33 59.33 59.78 3.10 67.05
63.30 60.88 53.02 56.36 59.11 3.30 65.35
66.60 65.63 57.76 64.91 63.56 2.66 72.19
4 Drug therapy (»-25)
M
SD
65.09 64.76 56.97 59.31 61.20 2.63 67.59
74.42 71.72 55.32 66.92 70.47 1.89 78.17
6.26 6.99 8.55 10.89 8.42 1.07 7.96
(n = 45)
Note. Treatment group means are adjusted means (for the effect of the covariate, pretreatment scores on the same variable, used in the subsequent comparative analyses). These analyses involved only subjects from the four treatment groups; means for normal subjects (not adjusted) are presented for comparative purposes only. * Variables for which a high score is favorable, or less indicative of depression. Average satisfaction is scaled so that a low score is favorable.
tempted of these effects. Second, it is clear from Table 2 that for none of the seven outcome variables was the Treatment Group factor found to interact with the Time factor. Our interest, therefore, is in the Treatment Group main effects found to be significant. As seen in Table 2, three of the seven outcome variables yielded such an effect: the personal activity, social, and mood variables. For each of these, follow-up pairwise multiple comparisons were conducted, yielding the results in the far right column of Table 2. Here we see that for each dependent variable, the Group 3 (behavior therapy) mean was highest, differing significantly from the Group 2 (relaxation therapy) mean in each case and, for the personal activity dependent variable, from the psychotherapy group mean as well.
Thus, the pattern seen in our earlier study (McLean & Hakstian, 1979)—in the analyses of both immediate posttreatment results as well as 3-month follow-up results—was replicated. Behavior therapy means were highest on both the social and mood dependent variables in the present analyses involving means aggregated over a 2.25-year follow-up period. The present finding regarding the personal activity outcome over the 2.25-year follow-up period, however (i.e, in which the behavior therapy mean was significantly higher than both the psychotherapy and relaxation therapy means), was not obtained in the earlier analyses of immediate posttreatment and 3-month follow-up results, and thus it represents something of a sleeper effect. The trend of disproportionate dropout found during the
Table 2 Results ofUnivariate Analyses ofCovariance of Seven Outcome Measures at Six Time Points F ratios for effects'
Dependent variable
MS, for treatment (df=\\6)
Treatment F
MS, for time and interaction11
Time F
Interaction F
Significant pairwise multiple comparisons'
Cognitive Coping Personal activity Social Somatic indicators Average satisfaction Mood
436.23 381.17 279.51 532.38 539.39 10.16 608.04
0.85 2.50* 3.99** 4.78** 1.39 2.03 2.79*
75.61 80.73 73.89 104.59 1 10.23 1.47 121.05
1.61 1.47 2.71* 2.34* 1.66 2.15* 1.74
0.20 0.44 1.05 1.56* 0.63 1.09 1.05
None None 3 vs. 1;3 vs. 2 3 vs. 2 None None 3 vs. 2
Note. For each dependent variable analyzed, the pretreatment scores on the same variable were used as covariate. * MSs for effects are reproducible by F (for effect) x MS (used to test that effect). b The dffor Time and for Treatment X Time interaction effects varied depending on the necessary adjustment for nonsphericity. 0 These multiple comparisons were conducted by the generalized studentized range statistic and were performed after a significant Treatment main effect on the marginal treatment group means. *p .75. Thus there was no evidence whatsoever of differential rates of additional treatment between the treatment groups.
Alternative Analysis of Treatment Groups Finally, an attempt was made to represent some of the parametric results given in Table 1 in somewhat different form. We calculated the percentages of subjects in each of the treatment groups whose unadjusted, aggregated (over the six time periods) subject means lay above a point in the normal, nondepressed group distribution (aggregated in a similar fashion) that was one standard deviation below the normal group mean. (We note here that of the original 55 nondepressed subjects, complete data at all time points were available on 45, and it is this subset that was used in the present calculations and is represented in Table 1.) Although admittedly somewhat arbitrary, this point was chosen as representing a reasonable upper region (upper 84% in a normal distribution) of nondepressed scores on the relevant dependent variables (i.e., those on which significance had been attained in the earlier analyses: the personal activity, social, and mood variables). Inferential comparative tests on these four (treatment group) percentages were then conducted for each dependent variable in turn, using procedures described by Marascuilo (1966). For the personal activity and social variables, these analyses yielded nonsignificant results, but for the mood dependent variable, the analysis of the four percentages (psychotherapy, 35.7%; relaxation therapy, 25.7%; behavior therapy, 63.6%; and drug therapy, 28.0%) yielded a statistically significant result, x2(3, N=l2l) = 13.48, p < .01. Follow-up multiple comparisons were performed (with alpha set to .05), and the behavior therapy group percentage was found to be significantly higher than the percentages for the relaxation therapy and drug therapy groups in turn (no other pairwise contrasts were significant) and from the aggregated
APA-Con Clin Psvch
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percentage of the other three groups. These results are summarized in Table 3. The results in Table 3 parallel, of course, those in Table 2, at least to some extent. A majority of behavior therapy subjects (63.6%) had posttreatment aggregated means (over the six time points extending 2.25 years posttreatment) that were within the upper range of the normal, nondepressed distribution of parallel aggregated means. This finding suggests that, over this follow-up period, the mood variable scores of the behavior therapy subjects were roughly parallel to those of the normal subjects. This result was not found, however, for the subjects in the other three treatment groups.
Discussion Our primary finding was that exposure to behavior therapy (10 hr) had a prophylactic influence over a 2.25-year posttreatment follow-up period for depressed patients, relative to a treatment control condition, whereas other therapies did not. Specifically, over the 27-month follow-up period, behavior therapy patients were significantly improved in mood, more socially active, and more personally productive, compared with treatment control group patients. Psychotherapy and pharmacotherapy patients were not distinguished from treatment control patients during the follow-up period on any outcome measure. The detection of treatment group differences was largely due to the inclusion of a treatment control condition (relaxation therapy), which contrasted most strongly with the behavior therapy group; the psychotherapy and pharmacotherapy groups assumed intermediate positions on most outcome measures. As seen in Table 1, the behavior therapy group was strongest, over the 27-month period, on six of seven outcome measures, although for only three of these were the differences statistically significant. In contrast, the pharmacological group performed best on one of six measures, and the psychotherapy group on zero of six measures. It is possible that behavior therapy patients fared better over the course of follow-up due to the directive nature of their therapy experience, which encouraged adaptive problem solving, social involvement, practical goal attainment, and new ways of interpreting and tolerating emotional distress. Also, behavior therapy patients were taught to expect, and were prepared for, relapse challenges. It should be noted that the behavioral treatment in this study consisted of both cognitive and behavioral elements sufficiently intermixed that attribution of outcome as a function of treatment element (i.e, cognitive vs. behavioral) was not possible. In any case, Rehm, Kaslow, and Rabin (1987) found that self-control therapy for depression was effective regardless of whether cognitive or behavioral treatment targets were pursued, and it appears that cognitive and behavioral prescriptions are common in both cognitive and behavioral treatments regardless of title. Following Kazdin's (1982) suggestion to make normative comparisons by contrasting client status with that of nondisturbed, normal peers, and in line with the recommendation of Jacobson, Follette, and Revenstorf (1984) to report psychotherapy outcome results in ways other than group treatment means,
Fri Jul 13 22:40:38 1990
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SURVIVAL OF DEPRESSION TREATMENT EFFECTS
Table 3 Percentages of Subjects by Group With an Aggregated Mean on the Mood Variable in the Upper Region of the Normal Group Score Distribution and Significance Test Results
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Treatment group
2
3
4
Relaxation therapy
Behavior therapy
Drug therapy
Subjects
1 Psychotherapy
n
28
35
33
25
% in specified region
35.7
25.7
63.6
28.0
Significant multiple comparisons* 3 vs. 2; 3 vs. 4 3 vs. (1,2, 4)
Note. The region of interest in the nondepressed score distribution is that part of the distribution occurring above one standard deviation below the mean. • Overall test: X2(3) = 13.48, p < .01.
we found, in this study, that approximately twice as many patients from the behavior therapy condition (i.e., 63.4%) fell within one standard deviation of the mean of the normal, nondepressed group distribution on depressed mood (aggregated across all six assessment points), compared with patients from the other treatment groups. In summarizing the treatment and follow-up results, the behavior therapy condition resulted in significantly fewer treatment dropouts during the course of treatment, posted the best immediate treatment results, and was the only treatment group to be distinguished from the treatment control condition during follow-up. The maintenance of improvement on several key outcome variables over a 2.25-year follow-up of unipolar depressed patients, after a relatively brief treatment exposure of 10 hr, has important implications for the development of prevention strategies. Our study had a number of methodological strong points. It represents the 'first depression treatment study to use a treatment control condition and a nondepressed, normal contrast group through both treatment and follow-up. Additionally, the relatively large number of subjects probably lent statistical power to the detection of group differences that may have eluded smaller studies (Nietzel et al, 1987), and the use of six posttreatment assessment points served to provide a more representative sample of patient adjustment over follow-up than is normally reported. Finally, this study used a multidimensional assessment strategy in an attempt to evaluate more comprehensively the range of symptom and personal adjustment areas considered relevant to depression: seven dimensions, each derived from a number of questionnaire responses. A limitation of our study stems from the absence of diagnostic classification at selected intervals over the follow-up period. Had such diagnostic information been obtained, it would have permitted comparability between studies and might have permitted outcome prediction. Gonzales, Lewinsohn, and Clarke (1985), for example, found the recovery rate for treated depressives to be significantly different, depending on whether the diagnosis was major depressive disorder, intermittent depressive disorder, or superimposed depressive disorder, according to Research Diagnostic Criteria (Spitzer, Endicott, & Robins, 1978). Despite this limitation, our study showed that the benefits of cognitive-behavioral therapy for the treatment of unipo-
lar depression were superior to those of both nondirective psychotherapy and pharmacotherapy when delivered alone and were enduring over time.
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PETER D. MCLEAN AND A. RALPH HAKSTIAN
(IPX) and drugs in the treatment of depression. Pharmacopsychiatry, 20, 3-7. Lubin, B. (1965). Adjective checklists for measurement of depression. Archives of General Psychiatry, 12, 57-62. Marascuilo, L. A. (1966). Large-sample multiple comparisons. Psychological Bulletin, 65, 280-290. McLean, P. D., & Hakstian, A. R. (1979). Clinical depression: Comparative efficacy of outpatient treatments. Journal of Consulting and Clinical Psychology, 47, 818-836. Nietzel, M. T, Russell, R. L, Hemmings, K. A, & Gretter, M. L. (1987). Clinical significance of psychotherapy for unipolar depression: A meta-analytic approach to social comparison. Journal of Consulting and Clinical Psychology, 55,156-161. National Institute of Mental Health/National Institutes of Health (NIMH/NIH) Consensus Development Conference Statement. (1985). Mood disorders: Pharmacological prevention of recurrences. American Journal of Psychiatry, 142, 469-476. Nystrbm, S. (1979). Depressions: Factors related to 10-year prognosis. Ada Psychiatrica Scandinavica, 60, 225-238. Rehm, L. P., Kaslow, N. J, & Rabin, A. S. (1987). Cognitive and behav-
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