Journal of Psychosomaric Printed in Great Britain.
Research,
Vol. 36, No. 3, pp. 215-206.
MULTIMODAL
1992.
TREATMENT
CHRONIC PAIN: A QUANTITATIVE
CO22-3999/92 $S.oO+.OO Pergamon Press plc
PROGRAMMES ANALYSIS
FOR
OF EXISTING
RESEARCH DATA A. CORRY (Received
26 June
G.
LINSSEN
1991; accepted
and PHILIP
SPINHOVEN
in revised form 21 September
1991)
Abstract-This article reviews the empirical data obtained in existing studies on the multimodal treatment of chronic pain. The majority of these ‘treatment packages’ are based on a cognitive/behavioural perspective. The articles for review were selected from the scientific literature on this subject which has appeared since the first publication of Fordyce in 1973. The following aspects have been analysed: the goal and structure of the treatment programmes; the method of evaluating treatment results; and the indications for treatment. Programmes for in-patients and out-patients have been compared because it is very likely that there are differences between the treatment methods and study populations. The interval validity and clinical relevance of the available research are discussed in the conclusion.
INTRODUCTION OWING to the complexity of chronic pain, an increasing number of disciplines have started to collaborate. Inter-disciplinarity makes it possible to exchange knowledge, to develop multimodal treatment programmes and to set up relevant clinical scientific research. In the United States alone, there are more than 1000 pain centres which apply largely multimodal programmes for the treatment of chronic pain [ 11. These programmes generally adopt a cognitive behavioural orientation [ 21. Clinical scientific research into these multimodal programmes, however, is less widespread. Various reviews of the available clinical research have been published [l, 3-111. This article discusses the method of reporting on programmes for the treatment of patients with chronic pain in the pain literature which has been published in the English language. Although this review somewhat overlaps the earlier publications, it aims, in addition to analysing the content and structure of the programmes, in more detail at isolating the criteria used to establish the efficacy of the programmes and at describing the characteristics of the patient population. Multimodal programmes are defined as programmes which contain various treatment modalities (e.g. physical exercises and relaxation training and information) and programmes in which in addition various disciplines cooperate. Back schools which only provide physical therapeutic information [ 12, 131 were nor included in this review. However, Back schools which in addition cooperate with e.g. a psychologist for psychological education and relaxation training [ 141 were included. This review comprises 32 multimodal programmes from 23 pain centres in the United States [ 15-531, five pain centres in Europe [ 54-591, one in Canada [ 601 and one in New Zealand [ 611. Two publications [ 33,611 pertained to two programmes
Author to whom correspondence should be addressed: A. Carry G. Linssen, Department of Psychiatry, B 1 P, University Hospital Leiden, Rijnsburgerweg 10, 2333 AA, Leiden. The Netherlands. 275
A. C. Cl.
276
LINSSEN
and PH. SPINHOVEN
in one pain centre. Table I shows the location of these centres in chronological order (column 1) and the reference of the publication in question (column 2, only the first author is mentioned) and the clinical setting, i.e. in-patient, in-out-patient (in-patient programmes continued on out-patients) and out-patient (column 3). In cases where several studies have been published on a programme with the same content from one pain centre, mostly the most recent article was used (indicated with * in the text) to avoid accumulation of the same results. Sometimes the data were completed by extracting them from another article on the same pain centre. TABLE I.-SURVEY
OF PAIN CENTRES AND MULTIMODAL TREATMENT PROGRAMMES FOR CHRONIC
Location
PAIN
Authors
6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27.
Portland, Oregon Rochester, Minnesota Toronto, California Hamilton, Ontario Grand Rapids, Michigan Atlanta, Georgia Durham, North Carolina Waukesha, Wisconsin Duluth, Minnesota Boston, Massachusetts Mesa, Arizona Selpulveda, California Uppsala, Sweden Omaha, Nebraska St. Louis, Missouri Birmingham, Alaska Madison, Wisconsin Columbia, Missouri Louvain, Belgium Bangor, Maine Maastricht, Netherlands Auckland, New Zealand
Fordyce 1973 * Greenhoot 1974*, Sternbach 1974 Cairns 1976* Anderson 1977, Hudgens 1979 Roberts 1980* Gottlieb 1977, 1979, 1982, McArthur 1987* Newman 1976, 1978*, Smith 1988 Swanson 1979*, Manna 1990 Robinson 1980” Herman 1981* Motiff 198 1 * Chapman 1981* Keefe 198 1 * Tyre 1981* Cinciripini 198 1 * Aronoff 1982, 1982, Kleinke, 1988* Lutz 1983* Cohen 1983, Heinrich, 1985* Linton 1984, 1985* Meilman 1985*, Guck 1985 Duckro 1985/86* Dolce 1986* Malec 1981*, Timming 1980 Armentrout 1978, Moore 1986* Stans 1989* Gallon 1989* Keijsers 1989* Peters 1990*
28. 29. 30.
London, U.K. Van Nuys, California Leiden, Netherlands
Skinner 1990* Deardorf 199 I* Spinhoven, 1991*,
1. 2. 3. 4.
Seattle, Washington San Diego, California Downey, California Minneapolis, Minnesota
5. Pomona,
California
*Articles selected for review. .tBoth treatment packages described
CONTENT
AND STRUCTURE
in this article
Linssen
1990
were selected
OF THE TREATMENT
in-/out-patient in-patient in-/out-patient in-/out-patient in-patient in-patient in-patient out-patient out-patient out-patient out-patient in-patient in-patient in-patient in-patient in-/out-patient out-patient (2t) out-patient in-patient out-patient in-/out-patient in-patient in-patient in-/out-patient in-patient out-patient in- + outpatient (2t) out-patient in-/out-patient out-patient
for review.
PROGRAMMES
In general, the aim of the programmes was described as teaching patients better ways of living with the pain or coping with the pain. Based on the assumption that the pain will continue after treatment, the treatment is aimed at achieving a more internal pain locus of control orientation and more adaptive pain coping mechanisms. Many different treatment components have been applied in the various multimodal
Multimodal
treatment
of chronic
271
pain
programmes for the treatment of chronic pain. Figure 1 shows the percentage of programmes in which the various treatment components were applied. The mean number of components in the in-patient programmes was 6.9; in the out-patient programmes 4.8. ,o(), ~. -. -.. ~~~~~~~~ a
!
I e d i
80
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I.
Fam/mar:
family
marital
therapy;
occupat: occupational
therapy;
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therapy.
In accordance with the more traditional treatment of especially chronic back pain, it appeared that physical therapy can in fact be viewed as a standard form of treatment, but always in combination with sometimes two but, in the majority of cases, three of more treatment components. Relaxation training (sometimes in the form of biofeedback) was applied in 88 % of the programmes. Education aimed at increasing an internal attribution of pain (the patient him/herself controls pain) instead of an external attribution (medication/somatic treatment controls pain) and at learning better ways of coping with the pain, usually formed part of the programmes. Medication reduction was found in 69% of the programmes. The in-patient programmes were particularly responsible for this high figure (18 out of the 20 in-patient programmes v 4 out of the 12 out-patient programmes). Medication reduction is achieved by promoting gradual and systematic withdrawal of analgesics, narcotics or tranquillizers. Often these medications are combined into a single mix, which is delivered in a colour- and taste-masking vehicle (a pain cocktail with cherry syrup or a capsule). The resulting mix is taken at fixed time intervals, around the clock. It is never taken in the intervals, should it be requested. The decrease in medications is achieved by gradually withdrawing active ingredients from the vehicle while the total volume remains the same (cf. Fordyce [ 31). Because most of the programmes combined behavioural interventions (like medication reduction) with cognitive interventions (like education) it seems justified to qualify these programmes as forms of cognitive-behaviour therapy. In in-patient programmes behaviour modification was emphasized, in out-patient programmes it was cognitive modification. In behaviour modification the focus is on changing the pain behaviours. Goals of treatment mostly were: to reduce medication intake; to
278
A. C. G. LINSSEN and PH. SPINHOVEN
decrease the avoidance of activities because of pain; to increase selected exercise tolerance; to increase walking; and to increase general social and work activities. In cognitive modification patients are first encouraged to shift from a purely sensory view of pain to a multicomponent view. This is sometimes done by means of a simplified explanation of the gate control theory of pain (Melzack, 1973 [ 621 , Linssen [54] and Skinner [57] ). Next patients are taught cognitive skills to deal with stress and pain, e.g. by means of cognitive restructuring, visualization and imagery techniques. The agenda of the in-patient programmes usually filled whole days. Therefore the duration stated in in-patient reports was generally expressed in terms of weeks or days. Converted into days, the mean duration was 33 days. The out-patient part of the combined programmes is not included in this figure, because their duration was hardly ever mentioned. The treatment duration of out-patient programmes was usually expressed by the number of sessions (varying in length from 1.5-4 hr, usually held weekly). In their extensively day-filling out-patient programme, Motiff and Van Ostenberg [44] expressed the duration in weeks: 9 weeks. This has somewhat arbitrarily been converted into sessions: 50 sessions. The 30 days mentioned by Duckro er al. [ 251 were converted into 30 sessions. As a result the mean number of sessions was 16.6. The form of treatment depended on the treatment setting. Nine out of the twelve out-patient programmes were conducted on a group of patients, two on individuals and one on a combination of group/individuals. In 14 out of the 20 in-patient programmes, the treatment was mainly performed individually, in which one treatment (often information) and, in some cases, more than one treatment component, was performed in a group format. Three programmes comprised mainly group treatment and the remaining three programmes comprised only individual treatment. TREATMENT
EVALUATION
The type of dependent variables used in assessing therapy outcome deserves special attention because it reflects what the clinical researchers understand by a good treatment result. Figure 2 shows the percentage of programmes in which the various dependent variables were applied. The dependent variables measured most often in the out-patient programmes were: pain intensity or nuisance from the pain (‘pain’), activity level (‘activ’), use of medication (‘medic’) and affective variables (‘affect’-often depression). In the inpatient programmes, the dependent variables measured most often were: pain intensity or nuisance from the pain, activity level, use of medication and to a lesser extent aft‘ective variables and physical measures (‘phys m’). Physical measures contained variables like walking distance, muscle strength, range of motion, strength and low back control (Heinrich [ 33 ] ). Profession/compensation (pr/cp) contained variables like being involved in litigation or receiving financial compensation and getting back to work. In the evaluation of the in-patient programmes, the use of medication was an important dependent variable. Medical consumption (‘med co’) variables used were the number of consultations
Multimodal treatment of chronic pain
279
e d n
(%I
P
a I n
a
m
C t I
;
V
C
a
F:
I e C
Y s
t
m
dependent FIG.
P > :
C w I t
m e d
C 0
0 :, e
r
variables
2.
of physicians and specialists, the number of hospitalizations and the quantity of pain medications used. Although the nuisance caused by the pain was usually measured, the intensity was not always regarded as an important effect measure. As mentioned above, the aim of most of the studies was to teach patients better ways of dealing with the pain and to feel less invalidated by their chronic pain. In several studies pain intensity was not measured at all [ 16, 21, 25, 26, 40, 41, 45, 47, 601. In addition, a wide range of dependent variables was measured which differed from study to study. Ten of the studies (especially on out-patient programmes) measured cognitive variables (‘cognit’). They used 10 different, sometimes selfinvented, methods. Some of the recent studies used standardized methods. Three studies [57, 58, 601 measured attribution of pain control with standardized, but different methods. One study [ 581 used a Coping Strategy Questionnaire, one [ 141 a standardized Pain Cognition List and a coping list and one [33] used the Health Locus of Control Scale. In accordance with the conclusions of the literature reviews mentioned in the introduction, it can be stated quite simply that the results of the programmes were positive in nearly all the publications. Some authors [27, 591 report a relapse at follow-up. However, as has also been mentioned by most of the reviewers, many of the studies show methodological shortcomings which inhibit a univocal interpretation of the results. The two most important shortcomings are the lack of control groups [ 63, 641 and component analyses [ 63, 651. The lack of control groups, for example, makes it impossible to compare (using me&t-analytic techniques) the effect of treatment vs no treatment or placebo treatment [ 661 . The lack of component analyses means that it is not clear whether the application of so many different treatment components is really necessary. Only four studies included a randomly assigned control group. These are recent studies, three on out-patient programmes, and one study which compared an in- and
A. C. G. LINSSENand
280
PH.
SPINHOVEN
an out-patient programme. Heinrich et al. [ 33 ] reported more favourable results with behaviour therapy than with physical therapy; both approaches were of identical duration. Linton et al. [56] found that regular therapy combined with behaviour therapy was more effective than regular therapy or a waiting period (despite the fact that the combined treatment required less treatment contact than regular therapy on its own). Keijsers et al. [ 141 found that a Back School programme was somewhat more effective than a waiting list control condition at post-treatment. Peters and Large [61] found comparable results for the in- and out-patient programme. Both treated groups showed better results at post-treatment than a no treatment group. In these studies follow-up data were not included. Guck et al. [ 321 and Deardorff [ 23 ] used a control group of patients selected for the (in-patient) programme but without insurance coverage. At follow-up (no post-treatment data) the treated groups were in a better condition than the no treatment groups. It was also observed that the majority of authors of articles on out-patient programmes had attempted to include some sort of comparison in their (uncontrolled) study design between: responders and non-responders [ 44, 601, or participants and non-participants (patients who were rejected, refused to cooperate or dropped-out) [ 25 ] , or various groups receiving compensation (with/without compensation, involved in litigation) [20] , or using patients as their own controls by including an extended baseline [58]. This approach was found in only three of the remaining 17 uncontrolled in-patient programmes [ 35, 41, 461. Furthermore, six studies did not report any follow-up data [ 31, 33, 53, 56, 57, 611 and several others reported only follow-up data. The duration of follow-up was usually 12 months. The method of evaluation, particularly follow-up data collection, leaves much to be desired: in some cases the precise methods or the questions asked, were not stated clearly; or use was made of retrospective data, particularly in inpatient programmes, which were obtained via telephone or mail enquiry and were not comparable to pretreatment measurements. INDICATIONS FOR TREATMENT Selection
criteria
The selection criteria were given in most of the in-patient programme reports and in seven of the twelve articles on the out-patient programmes. The following selection criteria were employed: an adequate trial of somatic-medical treatment; a pain problem of 6 (once 3) months’ duration or longer; patients had to explicitly demonstrate a high level of motivation (particularly inpatient programmes; no current treatment for psychiatric problems (approximately half of the reports); and not receiving benefits or being involved in litigation (three reports). Patient
characteristics
The majority of patients (in most cases at least 50%) suffered from (low) back pain. The mean percentage of male participants in the in-patient programmes was 47%
Multimodal
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281
(range 24-100%) and in the out-patient programmes: 49% (range 3 l-79 W). The mean age was the same in both programmes: 45 yr (range 39-55). The duration of pain was also comparable: + 7 yr (range 3-14). In the out-patient programme reports, few data were given on the number of surgical interventions. In the in-patient programmes, the patients appeared to have undergone usually more than one operation, with a maximum (average) of 4.3. However, it was not always clear whether the surgery was associated with the pain. Data on the number of employed participants in the out-patient studies were scarce. The four studies which did include this datum [ 33, 54, 60, 611 reported an average percentage of 33%. Although the reports on this aspect in the in-patient studies were not always clear, it could be deduced that few were employed (about 15%). Drop-outs For the generalization of treatment results to a relevant clinical population, it is important to establish the drop-out rate at various intervals during the study: from the selection phase to and including the follow-up measurement. Too few data were available in the studies we reviewed to establish the percentage of patients from the total patient population at the pain centres, who were considered eligible for admission to a treatment programme. Roberts and Reinhardt [46] mentioned that about half of their original population were selected for admission to the programme. About half of these patients (i.e. one quarter of the original population) actually participated. Although the article of Peters and Large [ 6 1 ] does not give numbers of excluded patients, they did report that of the 132 assessed patients, 78 (60%) completed the pretreatment assessments. For the out-patient studies, it was possible to establish the minimal drop-out rate between the start of treatment and the post-treatment assessment session in 50% of the studies. The mean drop-out rate reported was about 22% (range 13-35%). For only 4 of the 20 in-patient studies was it possible to establish this drop-out rate: 25 % . The drop-out rate between the start of treatment and the follow-up assessment session in the out-patient studies was 38 % and in the four in-patient studies 27 % . For the in-patient programmes the drop-out rate between the post-treatment assessment session and follow-up could be established in 9 of the 20 studies: an average rate of 24%. For this reason, we think that, for the in-patient studies, a better approach for establishing the drop-out rate between the start of treatment and followup would be by adding this percentage to the 25% drop-out between pre- and posttreatment, resulting in a drop-out rate of f 43 % between pretreatment and follow-up. Characteristics
of the responders
Several authors stated explicitly which dependent variables they considered crucial for dividing the patients into responders and non-responders [ 27, 35, 41, 42, 44, 46, 47, 51, 54, 601. A diversity of criteria was employed. Particularly ti.mctional impairment and medical consumption (including medication) were mentioned frequently. Attempts made by some of these authors to integrate the various dependent variables in a general effect score remain rather arbitrary [ 42, 44, 46, 47, 5 1, 601. Especially, the weighting of the various dependent variables remains problematic. Only Linssen
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A. C. G. LINSSEN and PH. SPINHOVEN
[ 541 created two effect scores which took into account the intercorrelations between the changes on the several dependent variables. After having defined responders/non-responders, their characteristics were examined by the researchers. The percentage of responders in these studies ranged from 47 to 79 % . A shorter history of (continuous) pain was mentioned in four studies as a predictor of a favourable treatment result [ 35, 46, 47, 511 Two studies [46, 541 found that successfully treated subjects reported lower levels of analgesic use at baseline. Furthermore, in some studies no relationship between psychological test scores and treatment result was found [ 35, 42, 441. Three studies [27, 36, 461 did find a relationship between psychological test scores and the result of treatment but they were contradictory. Other predictive variables were only found incidentally. SUMMARY
AND DISCUSSION
Despite the fact that there are over 1000 pain centres in the United States alone [ l] , the literature review only supplied data on 32 programmes at 30 centres. Content and structure
of the treatment
programmes
In general, the in-patient programmes are performed individually and are more multimodal and intensive than out-patient programmes. Although no clear evidence was found in the articles, it is likely that the in-patient programmes aim at more chronic patient populations. At present, no research data are available which indicate the need for more intensive and complex treatment for these patients. We could find only two studies in this field. One compared an out-patient relaxation programme comprising two 45-min sessions per week for a period of 5 weeks, to a more extensive day-filling programme comprising relaxation and operant conditioning 4 days per week for a period of about 4 weeks [ 551 . The patients were allocated at random into one of the study groups (and a waiting-list control condition). The treatment results were similar for both programmes; the costs of the former programme were estimated to be $350 per patient, whereas the latter were $3200 per patient. Peters and Large [ 611 also found comparable results for an in- and out-patient programme. Treatment
evaluation
The general opinion that chronic pain exerts an influence in many fields (emotional, social, physical, etc.) is reflected in the number of areas in which researchers evaluated the results of treatment. Frequently used effect variables in the studies reviewed included pain intensity or nuisance from the pain, activity level, use of medication and depression. In addition, a number of more diverse variables were measured in some of the studies. Only 10 studies tried to measure cognitive variables with measurement instruments ranging from self-invented measures for attitudes regarding pain and self-concept, to-in more recent studies [ 14, 33, 54, 57, 581 -standardized (but different) measures for attribution of control, and coping behaviour. This certainly reflects the burgeoning interest in cognitive processes in chronic pain patients and the lack of agreement regarding which cognitive variables are the most important in the treatment of chronic pain and how these variables should be measured [ 671. Making a useful integration of the many effect data remains problematical. Naliboff
Multimodal
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ef al. [ 681 have suggested an approach to data reduction by means of the calculation of factor scores based on the interdependence of scales. Turk and Rudy [ 691 have also criticized the separate consideration of medical, psychosocial and behavioural results. They suggested integrating these data by means of their ‘Multiaxial Assessment of Pain’ (MAP), comprising an integration of physical, psychosocial and behavioural data. Of the studies reviewed, only Linssen [54] calculated factor scores based on the interdependence of (residual) change scores and used these as effect scores. The results of our evaluation of the design, and methodology described in the articles we reviewed, can easily be summarized as follows: there is a lack of randomized control groups and reliable, non-retrospective (follow-up) data. i7re indication
for treatment
The analysis of the characteristics of the participating patients showed that many patients suffered from chronic (low) back pain. On average, they were middle-aged men or women who had been suffering from pain for more than 5 yr, had not responded to other types of medical treatment and did not have any acute psychiatric problems. In the in-patient programmes, the patients had usually undergone surgery at some time in the past and were mostly unemployed. Data on surgery and employment status were often lacking in the out-patient programme reports. Particularly in in-patient programmes, being well-motivated was a frequently mentioned inclusion criterion. In the study by Roberts and Reinhardt [46] who were admirably thorough in presenting vital research data, 25% of the patients who were not selected for the programme were rejected for this reason. It is unfortunate that, in 42% of the out-patient programmes, descriptions of the selection criteria used by the researchers are lacking. Therefore, it is not clear whether motivation often played a larger part in whether or not patients were selected for participation. In conclusion, further consideration of the selection criteria gives rise to the presumption that the treatment results from the evaluation studies on multimodal treatment cannot be generalized to patients with chronic pain without due caution. It cannot be excluded that, for multimodal treatment to be effective, the patients at least have to be well-motivated. Few authors mentioned the drop-out rates they encountered at various stages during the study. In as far as we were able to establish drop-out rates, they appeared to be considerable: between the start of treatment and the follow-up measurement approximately 45 % . If we add to this the data published by Roberts and Reinhardt [46] , i.e. that only about one quarter of the total patient population actually participated in the programme, then a great deal of caution is required when generalizing the research data to patients with chronic pain in general. Concluding
remarks
Our review of the literature does not incite much optimism: complicated, expensive programmes (especially in-patient programmes) are being applied to possibly highly selected patient groups without considering whether there are perhaps simpler methods; the way in which the success of the treatment is evaluated leaves a great deal to be desired; many studies did not incorporate a control group and/or reported
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mainly retrospective data, without mentioning the (probably large) drop-out rate in the various stages of the study and paid only slight attention to the indication for treatment. Particularly the lack of univocal data makes it difficult to interpret the results. More studies which try to achieve a level of methodological rigour at least comparable to some of the more recent studies [ 14, 23, 32, 33, 611 are urgently needed to further investigate the absolute and relative efficacy of multimodal programmes. REFERENCES pain treatment programs: Current status. Clin J Pain 1985; 1: 3 l-38. 1. CRUE BL. Multidisciplinary 2. TURK DC, MEICHEN~AUM D, GENES M Pain and Behavioral Medicine: A Cognitive-Behaviornl Perspective. New York: Guilford Press, 1983. 3. FORDYCE WE. Behavioral Methods for Chronic Pain and Illness. St Louis: C.V. Mosby, 1976. 4. LINTON SJ. Behavioral approaches to low back pain. Stand .I Behav Ther 1979; 8: 121-132. 5. LINTON SJ. A critical review of behavioral treatments for chronic benign pain other than headache. Br .I Clin Psycho1 1982; 21: 321-337. 6. LINTON SJ. Behavioral remediation of chronic pain: A status report. Pain 1986; 24: 125-141. 7. BLOCK AR. Multidisciplinary treatment of chronic low back pain: a review. RehabiI Psychof 1982; 27: 51-63. pain 8. ARONOFF GM, EVANS WO, ENDERS PL. A review of follow-up studies of multidisciplinary units. Pain 1983; 16: l-11. 9. TURK DC, FLOR H. Etiological theories and treatments for chronic back pain. II. Psychological models and interventions. Pain 1984; 19: 209-233. management of patients with 10. ANDERSON EF, HEGSTRUM JA, CHARBONEAU GJ. Multidisciplinary chronic low back pain. Clin J Pain 1985; 1: 85-90. 11. FORDYCE WE, ROBERTS AH, STERNBACH RA. The behavioral management of chronic pain: A response to critics. Pain 1985; 22: 113-125. 12. LANKHORST GJ, VAN DE STADT RJ, VOGELAAR TW, VAN DER KORST JK, PREVO AJH. The effect of the Swedish Back School in chronic idiopathic low back pain. A prospective controlled study.
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28. GOTTLIEB H, ALPERSON BL, KOLLER R. Low back pain comprehensive rehabilitation program: A follow-up study. Arch Whys Med Rehabil 1982; 63: 458-461. 29. GOTTLIEB H, ALPERSON BL, KOLLER R, H~CKERSMITH V. An innovative program for the restoration of patients with chronic back pain. Phys Ther 1979; 59: 996-999. 30. GOTTLIEB H, STRITE LC, KOLLER R, MADORSKY A, HOCKERSMITH V, KLEEMAN M, WAGNER J. Comprehensive rehabilitation of patients having chronic low back pain. Arch Phys Med Rehabil 1977; 58: 101-108. 3 1. GREENHOOT JH, STERNBACH RA. Conjoint treatment of chronic pain. Adv Neural 1974; 4: 595-603. 32. GUCK TP, SKULTETY FM, MEILMAN PW, DOWD ET. Multidisciplinary Pain Centre follow-up study: Evaluation with a no-treatment control group. Pain 1985; 21: 295-306. 33. HEINRICH RL, COHEN MJ, NALIBOFF BD, COLLINS GA, BONEBAKKER AD. Comparing physical and behavior therapy for chronic low back pain on physical abilities, psychological distress, and patients’ perceptions. J Behav Med 1985; 8: 61-78. 34. HUDGENS A. Family-oriented treatment of chronic pain. J Mar Fam Ther 1979; 5: 67-78. 35. KEEFE FJ, BLOCK AR, WILLIAMS RB, JR, SURWIT RS. Behavior treatment of chronic low back pain; Clinical outcome and individual differences in pain relief. Pain 1981; 11: 221-231. 36. KLEINKE CL, STEPHENSON SPANGLER A, JR. Predicting treatment outcome of chronic back pain patients in a multidisciplinary pain clinic: methodological issues and treatment implications. Pain 1988: 33: 41-48. 37. LUTZ RW, SILBRET M, OL~HAN N. Treatment outcome and compliance with therapeutic regimens: Long-term follow-up of a multidisciplinary pain program. Pain 1983; 17: 301-308. 38. MALEC J, CAYNER JJ, HARVEY RF, TIMMINC RC. Pain management: Long-term follow-up of an inpatient program. Arch Phys Med Rehabil 1981; 62: 369-372. 39. MARUTA T, SWANSON DW, MCHARDY MJ. Three year follow-up of patients with chronic pain who were treated in a multidisciplinary pain management centre. Pain 1990; 41: 47-53. 40. MCARTHUR DL, COHEN MJ, GOTTLIEB HJ, NALIBOFF BD, SCHANDLER SL. Treating chronic low back pain. I. Admissions to initial follow-up. Pain 1987; 29: l-22. 41. MCARTHUR DL, COHEN MJ, GOTTLIEB HJ, NALIBOFF BD, SCHANDLER SL. Treating chronic low back pain. II. Long-term follow-up. Pain 1987; 29: 23-38. 42. MEILMAN PW, SKULTETY FM, GUCK TP, SULLIVAN K. Benign chronic pain: 18.month to IO-year follow-up of a multidisciplinary pain unit treatment program. Clin J Pain 1985; 1: 131-137. 43. MOORE JE, ARMENTROUT DP, PARKER JC, KIVLAHAN DR. Empirically derived pain-patient MMPI subgroups: Prediction of treatment outcome. J Beh Med 1986; 9: 51-63. 44. MOTIFF P, VAN OSTENBERG DL. Results of a 9-week out-patient multi-modal chronic pain program. Paper presented at the Third World Congress on Pain of the International Association Study of Pain, Edinburgh, Scotland, 11 September, 1981. 45. NEWMAN RI, SERES JL, YOSPE LP, GARLINGTON B. Multidisciplinary treatment of chronic pain: Long-term follow-up of low-back pain patients. Pain 1978; 4: 283-292. 46. ROBERTS AH, REINHARDT L. The behavioral management of chronic pain: Long-term follow-up with comparison groups. Pain 1980; 8: 151-162. 47. ROBINSON GE. A combined approach to a medical problem. The Canadian Back education unit. Can J Psych& 1980; 25: 138-142. 48. SERES JL, NEWMAN RJ. Results of treatment of chronic low back-pain at the Portland Pain Centre. J Neurosurg 1976; 45: 32-36. 49. SMITH GT, HUGHES LB, DUVALL RD, ROTHMAN S. Treatment outcome of a multidisciplinary centre for management of chronic pain: A long-term follow-up. Clin J Pain 1988; 4: 47-49. 50. STERNBACH RA. Pain Patients: Traits and Treatment. New York: Academic Press, 1974. 51. SWANSON DW, MARUTA T, SWENSON WM. Results of behavior modification in the treatment of chronic pain. Psychosom Med 1979; 41: 55-61. 52. TIMMING RC, CAYNER JJ, MALEC JF, HARVEY RF, SCHWETTMANN RS, CHOSEY J. Inpatient treatment program for chronic pain. Wisconsin Med J 1980; 79: 23-26. 53. TYRE TE, ANDERSON DL. Inpatient management of the Chronic Pain Patient: A one year follow-up study. J Fam Pratt 1981; 12: 819-827. 54. LINSSEN ACG. Pijnbeheersing. Een cursus voor mensen met rugpijn. University of Leiden, Doctoral Thesis, 22 mei 1990. 55. LINTON SJ, G~TESTAM KG. A controlled study of the effects of applied relaxation and applied relaxation plus operant procedures in the regulation of chronic pain. Br J CZin Psychof 1984; 23: 291-299. 56. LINT~N SJ, MELIN L, STJERNL~~F K. The effects of applied relaxation and operant training on chronic pain. Behav Psychother 1985; 13: 87-100. 57. SKINNER JB, ERSKINE A, PEARCE S, RUBENSTEIN I, TAYLOR M, FOSTERS C. The evaluation of a cognitive behavioural treatment programme in outpatients with chronic pain. J Psychosom Res 1990; 34: 13-19.
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of 58. SPINHOVENPH, LINSSEN ACG. Behavioral treatment of chronic low back pain. I. Relationship coping strategy use to outcome. Pain 1991; 45: 29-34. 59. STANS L, GOSSENS L, VAN HOUDENHOVE B, ADRIAENSEN H, VERSTRAETEN D, VERVAEKE M, FANNES V. Evaluation of a brief chronic pain management program: Effects and limitations. Clin J Pain 1989; 5: 317-322. Pain 1981; IO: 79-86. 60. HERMAN E, BA~WSTE S. Pain control: Mastery through group experience. control trial evaluating in- and outpatient pain management 61. PETERSJL, LARGE RG. A randomised programs. Pain 1990; 41: 283-293. Harmondsworth: Penguin, 1973. 62. MELZACK R. The Puzzle off’uin. methods for pain control: A selective review. Pain 63. TAN SY. Cognitive and cognitive-behavioral 1982; 12: 201-228. interventions for chronic pain: A critical review. II. 64. TURNER JA, CHAPMAN CR. Psychological Operant conditioning, hypnosis, and cognitive behavioral tberapy. Pain 1982; 12: 23-46. 65. LINSSEN ACG, ZITMAN FG. Patient evaluation of a cognitive behavioral group program for patients with chronic low back pain. Sot Sci Med 1984; 19: 1361.-1365. Baltimore: J Hopkins 66. SMITH ML, GLASS GV, MILLER THJ. The Bene$ts cf Psychorherap. University Press, 1980. rugpijnklachten: Algemene therapeutische aspecten en onderzoek over 67. SPINHOVEN PH. Langdurige behandeling door middel van operante conditionering en cognitieve gedragstherapie. Dth 1987; 7: 310-331. 68. NALIBOFF BD, COHEN MJ, SWANSON GA, BONEBAKKER AD, MCARTHUR D. Comprehensive assessment of chronic low back pain patients and controls: Physical abilities, level of activity, psychological adjustment and pain perception. Pain 1985; 23: 121-234. assessment of chronic pain patients. Behav Res 69. TURK DC, RUDY TE. Towards a comprehensive l-her 1987: 25: 237-249.
Research,
Vol. 36, No. 3, pp. 215-206.
MULTIMODAL
1992.
TREATMENT
CHRONIC PAIN: A QUANTITATIVE
CO22-3999/92 $S.oO+.OO Pergamon Press plc
PROGRAMMES ANALYSIS
FOR
OF EXISTING
RESEARCH DATA A. CORRY (Received
26 June
G.
LINSSEN
1991; accepted
and PHILIP
SPINHOVEN
in revised form 21 September
1991)
Abstract-This article reviews the empirical data obtained in existing studies on the multimodal treatment of chronic pain. The majority of these ‘treatment packages’ are based on a cognitive/behavioural perspective. The articles for review were selected from the scientific literature on this subject which has appeared since the first publication of Fordyce in 1973. The following aspects have been analysed: the goal and structure of the treatment programmes; the method of evaluating treatment results; and the indications for treatment. Programmes for in-patients and out-patients have been compared because it is very likely that there are differences between the treatment methods and study populations. The interval validity and clinical relevance of the available research are discussed in the conclusion.
INTRODUCTION OWING to the complexity of chronic pain, an increasing number of disciplines have started to collaborate. Inter-disciplinarity makes it possible to exchange knowledge, to develop multimodal treatment programmes and to set up relevant clinical scientific research. In the United States alone, there are more than 1000 pain centres which apply largely multimodal programmes for the treatment of chronic pain [ 11. These programmes generally adopt a cognitive behavioural orientation [ 21. Clinical scientific research into these multimodal programmes, however, is less widespread. Various reviews of the available clinical research have been published [l, 3-111. This article discusses the method of reporting on programmes for the treatment of patients with chronic pain in the pain literature which has been published in the English language. Although this review somewhat overlaps the earlier publications, it aims, in addition to analysing the content and structure of the programmes, in more detail at isolating the criteria used to establish the efficacy of the programmes and at describing the characteristics of the patient population. Multimodal programmes are defined as programmes which contain various treatment modalities (e.g. physical exercises and relaxation training and information) and programmes in which in addition various disciplines cooperate. Back schools which only provide physical therapeutic information [ 12, 131 were nor included in this review. However, Back schools which in addition cooperate with e.g. a psychologist for psychological education and relaxation training [ 141 were included. This review comprises 32 multimodal programmes from 23 pain centres in the United States [ 15-531, five pain centres in Europe [ 54-591, one in Canada [ 601 and one in New Zealand [ 611. Two publications [ 33,611 pertained to two programmes
Author to whom correspondence should be addressed: A. Carry G. Linssen, Department of Psychiatry, B 1 P, University Hospital Leiden, Rijnsburgerweg 10, 2333 AA, Leiden. The Netherlands. 275
A. C. Cl.
276
LINSSEN
and PH. SPINHOVEN
in one pain centre. Table I shows the location of these centres in chronological order (column 1) and the reference of the publication in question (column 2, only the first author is mentioned) and the clinical setting, i.e. in-patient, in-out-patient (in-patient programmes continued on out-patients) and out-patient (column 3). In cases where several studies have been published on a programme with the same content from one pain centre, mostly the most recent article was used (indicated with * in the text) to avoid accumulation of the same results. Sometimes the data were completed by extracting them from another article on the same pain centre. TABLE I.-SURVEY
OF PAIN CENTRES AND MULTIMODAL TREATMENT PROGRAMMES FOR CHRONIC
Location
PAIN
Authors
6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27.
Portland, Oregon Rochester, Minnesota Toronto, California Hamilton, Ontario Grand Rapids, Michigan Atlanta, Georgia Durham, North Carolina Waukesha, Wisconsin Duluth, Minnesota Boston, Massachusetts Mesa, Arizona Selpulveda, California Uppsala, Sweden Omaha, Nebraska St. Louis, Missouri Birmingham, Alaska Madison, Wisconsin Columbia, Missouri Louvain, Belgium Bangor, Maine Maastricht, Netherlands Auckland, New Zealand
Fordyce 1973 * Greenhoot 1974*, Sternbach 1974 Cairns 1976* Anderson 1977, Hudgens 1979 Roberts 1980* Gottlieb 1977, 1979, 1982, McArthur 1987* Newman 1976, 1978*, Smith 1988 Swanson 1979*, Manna 1990 Robinson 1980” Herman 1981* Motiff 198 1 * Chapman 1981* Keefe 198 1 * Tyre 1981* Cinciripini 198 1 * Aronoff 1982, 1982, Kleinke, 1988* Lutz 1983* Cohen 1983, Heinrich, 1985* Linton 1984, 1985* Meilman 1985*, Guck 1985 Duckro 1985/86* Dolce 1986* Malec 1981*, Timming 1980 Armentrout 1978, Moore 1986* Stans 1989* Gallon 1989* Keijsers 1989* Peters 1990*
28. 29. 30.
London, U.K. Van Nuys, California Leiden, Netherlands
Skinner 1990* Deardorf 199 I* Spinhoven, 1991*,
1. 2. 3. 4.
Seattle, Washington San Diego, California Downey, California Minneapolis, Minnesota
5. Pomona,
California
*Articles selected for review. .tBoth treatment packages described
CONTENT
AND STRUCTURE
in this article
Linssen
1990
were selected
OF THE TREATMENT
in-/out-patient in-patient in-/out-patient in-/out-patient in-patient in-patient in-patient out-patient out-patient out-patient out-patient in-patient in-patient in-patient in-patient in-/out-patient out-patient (2t) out-patient in-patient out-patient in-/out-patient in-patient in-patient in-/out-patient in-patient out-patient in- + outpatient (2t) out-patient in-/out-patient out-patient
for review.
PROGRAMMES
In general, the aim of the programmes was described as teaching patients better ways of living with the pain or coping with the pain. Based on the assumption that the pain will continue after treatment, the treatment is aimed at achieving a more internal pain locus of control orientation and more adaptive pain coping mechanisms. Many different treatment components have been applied in the various multimodal
Multimodal
treatment
of chronic
271
pain
programmes for the treatment of chronic pain. Figure 1 shows the percentage of programmes in which the various treatment components were applied. The mean number of components in the in-patient programmes was 6.9; in the out-patient programmes 4.8. ,o(), ~. -. -.. ~~~~~~~~ a
!
I e d i
80
60 40 20
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:
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I.
Fam/mar:
family
marital
therapy;
occupat: occupational
therapy;
ind ther: individual
therapy.
In accordance with the more traditional treatment of especially chronic back pain, it appeared that physical therapy can in fact be viewed as a standard form of treatment, but always in combination with sometimes two but, in the majority of cases, three of more treatment components. Relaxation training (sometimes in the form of biofeedback) was applied in 88 % of the programmes. Education aimed at increasing an internal attribution of pain (the patient him/herself controls pain) instead of an external attribution (medication/somatic treatment controls pain) and at learning better ways of coping with the pain, usually formed part of the programmes. Medication reduction was found in 69% of the programmes. The in-patient programmes were particularly responsible for this high figure (18 out of the 20 in-patient programmes v 4 out of the 12 out-patient programmes). Medication reduction is achieved by promoting gradual and systematic withdrawal of analgesics, narcotics or tranquillizers. Often these medications are combined into a single mix, which is delivered in a colour- and taste-masking vehicle (a pain cocktail with cherry syrup or a capsule). The resulting mix is taken at fixed time intervals, around the clock. It is never taken in the intervals, should it be requested. The decrease in medications is achieved by gradually withdrawing active ingredients from the vehicle while the total volume remains the same (cf. Fordyce [ 31). Because most of the programmes combined behavioural interventions (like medication reduction) with cognitive interventions (like education) it seems justified to qualify these programmes as forms of cognitive-behaviour therapy. In in-patient programmes behaviour modification was emphasized, in out-patient programmes it was cognitive modification. In behaviour modification the focus is on changing the pain behaviours. Goals of treatment mostly were: to reduce medication intake; to
278
A. C. G. LINSSEN and PH. SPINHOVEN
decrease the avoidance of activities because of pain; to increase selected exercise tolerance; to increase walking; and to increase general social and work activities. In cognitive modification patients are first encouraged to shift from a purely sensory view of pain to a multicomponent view. This is sometimes done by means of a simplified explanation of the gate control theory of pain (Melzack, 1973 [ 621 , Linssen [54] and Skinner [57] ). Next patients are taught cognitive skills to deal with stress and pain, e.g. by means of cognitive restructuring, visualization and imagery techniques. The agenda of the in-patient programmes usually filled whole days. Therefore the duration stated in in-patient reports was generally expressed in terms of weeks or days. Converted into days, the mean duration was 33 days. The out-patient part of the combined programmes is not included in this figure, because their duration was hardly ever mentioned. The treatment duration of out-patient programmes was usually expressed by the number of sessions (varying in length from 1.5-4 hr, usually held weekly). In their extensively day-filling out-patient programme, Motiff and Van Ostenberg [44] expressed the duration in weeks: 9 weeks. This has somewhat arbitrarily been converted into sessions: 50 sessions. The 30 days mentioned by Duckro er al. [ 251 were converted into 30 sessions. As a result the mean number of sessions was 16.6. The form of treatment depended on the treatment setting. Nine out of the twelve out-patient programmes were conducted on a group of patients, two on individuals and one on a combination of group/individuals. In 14 out of the 20 in-patient programmes, the treatment was mainly performed individually, in which one treatment (often information) and, in some cases, more than one treatment component, was performed in a group format. Three programmes comprised mainly group treatment and the remaining three programmes comprised only individual treatment. TREATMENT
EVALUATION
The type of dependent variables used in assessing therapy outcome deserves special attention because it reflects what the clinical researchers understand by a good treatment result. Figure 2 shows the percentage of programmes in which the various dependent variables were applied. The dependent variables measured most often in the out-patient programmes were: pain intensity or nuisance from the pain (‘pain’), activity level (‘activ’), use of medication (‘medic’) and affective variables (‘affect’-often depression). In the inpatient programmes, the dependent variables measured most often were: pain intensity or nuisance from the pain, activity level, use of medication and to a lesser extent aft‘ective variables and physical measures (‘phys m’). Physical measures contained variables like walking distance, muscle strength, range of motion, strength and low back control (Heinrich [ 33 ] ). Profession/compensation (pr/cp) contained variables like being involved in litigation or receiving financial compensation and getting back to work. In the evaluation of the in-patient programmes, the use of medication was an important dependent variable. Medical consumption (‘med co’) variables used were the number of consultations
Multimodal treatment of chronic pain
279
e d n
(%I
P
a I n
a
m
C t I
;
V
C
a
F:
I e C
Y s
t
m
dependent FIG.
P > :
C w I t
m e d
C 0
0 :, e
r
variables
2.
of physicians and specialists, the number of hospitalizations and the quantity of pain medications used. Although the nuisance caused by the pain was usually measured, the intensity was not always regarded as an important effect measure. As mentioned above, the aim of most of the studies was to teach patients better ways of dealing with the pain and to feel less invalidated by their chronic pain. In several studies pain intensity was not measured at all [ 16, 21, 25, 26, 40, 41, 45, 47, 601. In addition, a wide range of dependent variables was measured which differed from study to study. Ten of the studies (especially on out-patient programmes) measured cognitive variables (‘cognit’). They used 10 different, sometimes selfinvented, methods. Some of the recent studies used standardized methods. Three studies [57, 58, 601 measured attribution of pain control with standardized, but different methods. One study [ 581 used a Coping Strategy Questionnaire, one [ 141 a standardized Pain Cognition List and a coping list and one [33] used the Health Locus of Control Scale. In accordance with the conclusions of the literature reviews mentioned in the introduction, it can be stated quite simply that the results of the programmes were positive in nearly all the publications. Some authors [27, 591 report a relapse at follow-up. However, as has also been mentioned by most of the reviewers, many of the studies show methodological shortcomings which inhibit a univocal interpretation of the results. The two most important shortcomings are the lack of control groups [ 63, 641 and component analyses [ 63, 651. The lack of control groups, for example, makes it impossible to compare (using me&t-analytic techniques) the effect of treatment vs no treatment or placebo treatment [ 661 . The lack of component analyses means that it is not clear whether the application of so many different treatment components is really necessary. Only four studies included a randomly assigned control group. These are recent studies, three on out-patient programmes, and one study which compared an in- and
A. C. G. LINSSENand
280
PH.
SPINHOVEN
an out-patient programme. Heinrich et al. [ 33 ] reported more favourable results with behaviour therapy than with physical therapy; both approaches were of identical duration. Linton et al. [56] found that regular therapy combined with behaviour therapy was more effective than regular therapy or a waiting period (despite the fact that the combined treatment required less treatment contact than regular therapy on its own). Keijsers et al. [ 141 found that a Back School programme was somewhat more effective than a waiting list control condition at post-treatment. Peters and Large [61] found comparable results for the in- and out-patient programme. Both treated groups showed better results at post-treatment than a no treatment group. In these studies follow-up data were not included. Guck et al. [ 321 and Deardorff [ 23 ] used a control group of patients selected for the (in-patient) programme but without insurance coverage. At follow-up (no post-treatment data) the treated groups were in a better condition than the no treatment groups. It was also observed that the majority of authors of articles on out-patient programmes had attempted to include some sort of comparison in their (uncontrolled) study design between: responders and non-responders [ 44, 601, or participants and non-participants (patients who were rejected, refused to cooperate or dropped-out) [ 25 ] , or various groups receiving compensation (with/without compensation, involved in litigation) [20] , or using patients as their own controls by including an extended baseline [58]. This approach was found in only three of the remaining 17 uncontrolled in-patient programmes [ 35, 41, 461. Furthermore, six studies did not report any follow-up data [ 31, 33, 53, 56, 57, 611 and several others reported only follow-up data. The duration of follow-up was usually 12 months. The method of evaluation, particularly follow-up data collection, leaves much to be desired: in some cases the precise methods or the questions asked, were not stated clearly; or use was made of retrospective data, particularly in inpatient programmes, which were obtained via telephone or mail enquiry and were not comparable to pretreatment measurements. INDICATIONS FOR TREATMENT Selection
criteria
The selection criteria were given in most of the in-patient programme reports and in seven of the twelve articles on the out-patient programmes. The following selection criteria were employed: an adequate trial of somatic-medical treatment; a pain problem of 6 (once 3) months’ duration or longer; patients had to explicitly demonstrate a high level of motivation (particularly inpatient programmes; no current treatment for psychiatric problems (approximately half of the reports); and not receiving benefits or being involved in litigation (three reports). Patient
characteristics
The majority of patients (in most cases at least 50%) suffered from (low) back pain. The mean percentage of male participants in the in-patient programmes was 47%
Multimodal
treatment
of chronic
pain
281
(range 24-100%) and in the out-patient programmes: 49% (range 3 l-79 W). The mean age was the same in both programmes: 45 yr (range 39-55). The duration of pain was also comparable: + 7 yr (range 3-14). In the out-patient programme reports, few data were given on the number of surgical interventions. In the in-patient programmes, the patients appeared to have undergone usually more than one operation, with a maximum (average) of 4.3. However, it was not always clear whether the surgery was associated with the pain. Data on the number of employed participants in the out-patient studies were scarce. The four studies which did include this datum [ 33, 54, 60, 611 reported an average percentage of 33%. Although the reports on this aspect in the in-patient studies were not always clear, it could be deduced that few were employed (about 15%). Drop-outs For the generalization of treatment results to a relevant clinical population, it is important to establish the drop-out rate at various intervals during the study: from the selection phase to and including the follow-up measurement. Too few data were available in the studies we reviewed to establish the percentage of patients from the total patient population at the pain centres, who were considered eligible for admission to a treatment programme. Roberts and Reinhardt [46] mentioned that about half of their original population were selected for admission to the programme. About half of these patients (i.e. one quarter of the original population) actually participated. Although the article of Peters and Large [ 6 1 ] does not give numbers of excluded patients, they did report that of the 132 assessed patients, 78 (60%) completed the pretreatment assessments. For the out-patient studies, it was possible to establish the minimal drop-out rate between the start of treatment and the post-treatment assessment session in 50% of the studies. The mean drop-out rate reported was about 22% (range 13-35%). For only 4 of the 20 in-patient studies was it possible to establish this drop-out rate: 25 % . The drop-out rate between the start of treatment and the follow-up assessment session in the out-patient studies was 38 % and in the four in-patient studies 27 % . For the in-patient programmes the drop-out rate between the post-treatment assessment session and follow-up could be established in 9 of the 20 studies: an average rate of 24%. For this reason, we think that, for the in-patient studies, a better approach for establishing the drop-out rate between the start of treatment and followup would be by adding this percentage to the 25% drop-out between pre- and posttreatment, resulting in a drop-out rate of f 43 % between pretreatment and follow-up. Characteristics
of the responders
Several authors stated explicitly which dependent variables they considered crucial for dividing the patients into responders and non-responders [ 27, 35, 41, 42, 44, 46, 47, 51, 54, 601. A diversity of criteria was employed. Particularly ti.mctional impairment and medical consumption (including medication) were mentioned frequently. Attempts made by some of these authors to integrate the various dependent variables in a general effect score remain rather arbitrary [ 42, 44, 46, 47, 5 1, 601. Especially, the weighting of the various dependent variables remains problematic. Only Linssen
282
A. C. G. LINSSEN and PH. SPINHOVEN
[ 541 created two effect scores which took into account the intercorrelations between the changes on the several dependent variables. After having defined responders/non-responders, their characteristics were examined by the researchers. The percentage of responders in these studies ranged from 47 to 79 % . A shorter history of (continuous) pain was mentioned in four studies as a predictor of a favourable treatment result [ 35, 46, 47, 511 Two studies [46, 541 found that successfully treated subjects reported lower levels of analgesic use at baseline. Furthermore, in some studies no relationship between psychological test scores and treatment result was found [ 35, 42, 441. Three studies [27, 36, 461 did find a relationship between psychological test scores and the result of treatment but they were contradictory. Other predictive variables were only found incidentally. SUMMARY
AND DISCUSSION
Despite the fact that there are over 1000 pain centres in the United States alone [ l] , the literature review only supplied data on 32 programmes at 30 centres. Content and structure
of the treatment
programmes
In general, the in-patient programmes are performed individually and are more multimodal and intensive than out-patient programmes. Although no clear evidence was found in the articles, it is likely that the in-patient programmes aim at more chronic patient populations. At present, no research data are available which indicate the need for more intensive and complex treatment for these patients. We could find only two studies in this field. One compared an out-patient relaxation programme comprising two 45-min sessions per week for a period of 5 weeks, to a more extensive day-filling programme comprising relaxation and operant conditioning 4 days per week for a period of about 4 weeks [ 551 . The patients were allocated at random into one of the study groups (and a waiting-list control condition). The treatment results were similar for both programmes; the costs of the former programme were estimated to be $350 per patient, whereas the latter were $3200 per patient. Peters and Large [ 611 also found comparable results for an in- and out-patient programme. Treatment
evaluation
The general opinion that chronic pain exerts an influence in many fields (emotional, social, physical, etc.) is reflected in the number of areas in which researchers evaluated the results of treatment. Frequently used effect variables in the studies reviewed included pain intensity or nuisance from the pain, activity level, use of medication and depression. In addition, a number of more diverse variables were measured in some of the studies. Only 10 studies tried to measure cognitive variables with measurement instruments ranging from self-invented measures for attitudes regarding pain and self-concept, to-in more recent studies [ 14, 33, 54, 57, 581 -standardized (but different) measures for attribution of control, and coping behaviour. This certainly reflects the burgeoning interest in cognitive processes in chronic pain patients and the lack of agreement regarding which cognitive variables are the most important in the treatment of chronic pain and how these variables should be measured [ 671. Making a useful integration of the many effect data remains problematical. Naliboff
Multimodal
treatment
of chronic
pain
283
ef al. [ 681 have suggested an approach to data reduction by means of the calculation of factor scores based on the interdependence of scales. Turk and Rudy [ 691 have also criticized the separate consideration of medical, psychosocial and behavioural results. They suggested integrating these data by means of their ‘Multiaxial Assessment of Pain’ (MAP), comprising an integration of physical, psychosocial and behavioural data. Of the studies reviewed, only Linssen [54] calculated factor scores based on the interdependence of (residual) change scores and used these as effect scores. The results of our evaluation of the design, and methodology described in the articles we reviewed, can easily be summarized as follows: there is a lack of randomized control groups and reliable, non-retrospective (follow-up) data. i7re indication
for treatment
The analysis of the characteristics of the participating patients showed that many patients suffered from chronic (low) back pain. On average, they were middle-aged men or women who had been suffering from pain for more than 5 yr, had not responded to other types of medical treatment and did not have any acute psychiatric problems. In the in-patient programmes, the patients had usually undergone surgery at some time in the past and were mostly unemployed. Data on surgery and employment status were often lacking in the out-patient programme reports. Particularly in in-patient programmes, being well-motivated was a frequently mentioned inclusion criterion. In the study by Roberts and Reinhardt [46] who were admirably thorough in presenting vital research data, 25% of the patients who were not selected for the programme were rejected for this reason. It is unfortunate that, in 42% of the out-patient programmes, descriptions of the selection criteria used by the researchers are lacking. Therefore, it is not clear whether motivation often played a larger part in whether or not patients were selected for participation. In conclusion, further consideration of the selection criteria gives rise to the presumption that the treatment results from the evaluation studies on multimodal treatment cannot be generalized to patients with chronic pain without due caution. It cannot be excluded that, for multimodal treatment to be effective, the patients at least have to be well-motivated. Few authors mentioned the drop-out rates they encountered at various stages during the study. In as far as we were able to establish drop-out rates, they appeared to be considerable: between the start of treatment and the follow-up measurement approximately 45 % . If we add to this the data published by Roberts and Reinhardt [46] , i.e. that only about one quarter of the total patient population actually participated in the programme, then a great deal of caution is required when generalizing the research data to patients with chronic pain in general. Concluding
remarks
Our review of the literature does not incite much optimism: complicated, expensive programmes (especially in-patient programmes) are being applied to possibly highly selected patient groups without considering whether there are perhaps simpler methods; the way in which the success of the treatment is evaluated leaves a great deal to be desired; many studies did not incorporate a control group and/or reported
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