Journal of Behavioral Medicine, Vol. 14, No. 1, 1991
Reliability and Validity of the Appraisal of Diabetes Scale Michael P. Carey, ~-4 Randall S. Jorgensen, 1.2 Ruth S. Weinstock 2,3 Robert P. Sprafkin, ~-3 Larry J. Lantinga, 1-3 C. L. M. Carnrike, Jr., 1 Marilyn T. Baker, 2 and Andrew W. Meisler ~ Accepted for publication: April 28, 1990
The present research evaluated the psychometric properties of a brief selfreport instrument designed to assess appraisal of diabetes. Two hundred male subjects completed the Appraisal of Diabetes Scale (ADS) and provided blood samples that were subsequently assayed to provide an index o f glycemic control (i. e., glycosylated hemoglobin). Subjects also completed either (a) additional measures o f diabetes-related health beliefs, diabetic daily hassles, perceived stress, diabetic adherence, and psychiatric symptoms or (b) the ADS on two additional occasions. Results indicated that the A D S is an internally consistent and stable measure o f diabetes-related appraisal. The validity o f the measure was supported by correlational analyses which documented the relationship between the A D S and several related self-report measures. KEY WORDS: diabetes; appraisal; stress; psychometrics.
Diabetes mellitus afflicts approximately 4 to 6 million Americans (Wing et al., 1987), most of whom must adopt a rigorous self-care regimen in order to manage their chronic condition. Although many diabetics manage their ~Syracuse University, Syracuse, New York 13244. ZSyracuse Veterans Administration Medical Center, Syracuse, New York. 3State University of New York Health Science Center at Syracuse, Syracuse, New York. 4To whom correspondence should be addressed at the Department of Psychology, 430 Huntington Hall, Syracuse University, Syracuse, New York 13244-2340. 43 0160-7715/91/0200-0043506.50/0 9 1991PlenumPublishingCorporation
Carey et al.
disease well and avoid serious complications, adherence to the diabetic regimen can be difficult and is often stressful. Just as diabetes can initiate the stress process, external stressors can disturb glucose metabolism (e.g., Cox et al., 1984) and affect the course of diabetes. Thus, the transactional relationship between stress and diabetes is important and warrants investigation. Current models of stress emphasize the mediating role of appraisal processes in the stress-health relationship. The empirical literature suggests that appraisal of a stressor may determine psychosocial outcomes of that stressor more accurately than do the actual characteristics of the stressor itself (Lazarus and Folkman, 1984). The relationship between appraisal and somatic health outcomes is less clear. In the case of diabetes, the way that a person appraises his or her disease is likely to influence overall morale or psychological adjustment. It is likely that diabetic-related appraisal will also influence how well a person will adhere to the diabetic regimen; adherence, in turn, will impact upon the course of the disease. Although these hypotheses are interesting, empirical investigation of these potential relationships has been hampered by the absence of a psychometrically sound measure of appraisal in diabetes. The purpose of this research was to examine the psychometric properties of a brief self-report questionnaire designed to assess a diabetic person's appraisal of his or her disease. We examined the internal consistency as well as the stability of this instrument; we also evaluated its validity by measuring the relationship between appraisal scores and (a) diabetic regimen adherence, (b) glycemic control, (c) health beliefs related to diabetes, (d) current stress, and (e) current psychological adjustment.
METHODS Subjects Two hundred adult males (M = 58.4 years of age) served as subjects; all subjects were outpatients receiving continuing care through the Diabetes Clinic at the Syracuse Veterans Administration Medical Center. The subjects were primarily Caucasian (91 ~ married (81%), and high school educated (M = 12.2 years). The mean duration of diabetes was 15 years, and 66~ of the patients were currently on insulin therapy.
Appraisal o f Diabetes Scale (ADS). The ADS consists of 7 items designed to assess an individual's appraisal of his or her diabetes. The items
Appraisal of Diabetes Scale
were developed on the basis of previous theory (i.e., Lazarus and Folkman, 1984) and research (i.e., Gong-Guy and Hammen, 1980; Hammen and Mayol, 1982) regarding appraisal processes. Some items were adapted from Hammen and Mayol's (1982) Attribution Questionnaire and customized to the diabetes context. A complete copy of the scale is given in Table AI (Appendix).
Diabetes Regimen Adherence Questionnaire (DRAQ-R; BrownleeDuffeck et al., 1987). The DRAQ-R is a 20-item self-report measure of behavioral adherence to the diabetic regimen. Subjects are asked to indicate the frequency with which they complete self-care behaviors required for good glycemic control; ratings are made along a 0 (never) to 5 (always) Likert scale. One summary score is obtained. Previous research with an earlier version of the DRAQ-R indicated that the measure is internally consistent [coefficient alpha = .79 (see Brownlee-Duffeck et al., 1987)]. Glycosylated Hemoglobin (HbAlc). Blood samples were collected from patients by venipuncture as a routine part of their regular outpatient care and later assayed to determine their HbAlc level. This measure is correlated with blood sugar level during the 8 weeks prior to testing (Gonen et al., 1977); HbAlc level is a commonly used estimate of glycemic control.
Diabetes Health Belief Questionnaire- Revised (DHBQ-R; BrownleeDuffeck et al., 1987). The DHBQ-R consists of 31 items designed to assess (a) perceived severity of diabetes and its complications (5 items), (b) perceived susceptibility to diabetic complications (4 items), (c) perceived costs of adherence (11 items), (d) perceived benefits of adherence to the diabetic regimen (5 items), and (e) cues for adherence (6 items). Subjects are asked to rate their beliefs with respect to each item along a 0 (not at all) to 5 (extremely) Likert scale. Data from only the perceived severity and perceived susceptibility subscales were used in this study. These two subscales were the only extant measures, known to us, which assessed a construct similar to the appraisal construct we were measuring; consequently, these two scales were used to determine the validity of the ADS. In previous research the DHBQ (see Brownlee-Duffeck et al., 1987) indicated good internal consistency (coefficient alphas = .66 and .73, respectively) for the two summary scores used in the current study. Diabetic Daily Hassles Scale (DDHS). This scale consists of 42 bothersome tasks or stressors (e.g., planning snacks or meals, urine testing) associated with the daily experience of having diabetes. The scale was modeled after the commonly used Daily Hassles measure (Kanner et al., 1981); all items were selected after consultation with persons having diabetes and with a diabetologist. For each item, subjects were asked to indicate whether or not they experienced that hassle during the last month and then to rate those hassles which they had experienced along a 5-point scale (1 = not severe at all, 5 = extremely severe). One summary score was obtained from
this instrument, which indicates the global severity of all diabetes-related hassles experienced. Calculation of coefficient alpha for the current sample yielded a value of .92, indicating strong internal consistency. Perceived Stress Scale (PSS; Cohen et al., 1983). The brief, 4-item version of the PSS was used to assess the subjects' appraisal of the amount of stress they experienced in the last month. The brief version of the PSS has been shown to be internally consistent (coefficient alpha = .72) and relatively stable [test-retest reliability over 2 months = .55 (see Cohen et al., 1983)]. One summary score is obtained. Psychiatric Symptom Index (PSI; Ilfeld, 1976). The PSI is a 29-item self-report instrument designed to measure a range of psychiatric symptoms (e.g., "feel fearful or afraid"). Subjects were asked to indicate how often they experienced each of the 29 symptoms on a 4-point Likert scale (0 = never, 3 = very often). The scale yields four summary subscales- depression, anxiety, anger, and cognitive disturbance; each of the subscales is internally consistent (coefficient alphas range from .77 to .84), and the concurrent validity of the PSI is well-established (see Ilfeld, 1976). Because we had no a priori hypotheses regarding cognitive disturbance only the first three subscales were used for the current study. Procedure Potential subjects were approached by a Research Assistant as they presented for their scheduled Diabetes Clinic appointment and were invited to participate in the study. If a subject consented to participate, one of two procedures was followed. One subsample of subjects (n -- 102) was asked to complete a battery that included the ADS, DRAQ-R, DHBQ-R, DDHS, PSS, and PSI. The other subsample of subjects (n = 98) was asked to complete only the ADS and to do so at three occasions: (a) just prior to having their blood drawn, (b) approximately 1 hr later after completing their clinic visit, and (c) 1 week later. (The 1-week retest was mailed to subjects; complete retest data were returned by 79% of the subjects.) Subjects in both subsamples were asked to provide blood for routine monitoring of HbAlc.
RESULTS The ADS item means (after reverse scoring appropriate items) and standard deviations are presented in Table I. Examination of the means reveals that subjects tended to rate themselves near the midpoint of the 5-point scale. The standard deviations indicate that all of the items had sufficient variance to contribute meaningfully to the summary score. The range, mean, and standard deviation o f the summary scores are presented in Table II.
Appraisal of Diabetes Scale
Table I. Means, Standard Deviations, Item-Remainder
Correlations, and Loadings for the Appraisal of Diabetes Scale Item
1 2 3 4 5 6 7
2.608 2.583 2.623 3.025 2.457 2.553 2.799
1.031 .758 .963 .943 .843 .734 1.143
.537 .416 .589 .462 .281 .324 .522
.715 -.578 .752 .641 .424 -.489 .698
~Negative loadings reflect items which were reversescored.
N e x t , to d e t e r m i n e w h e t h e r A D S scores d i f f e r e d by i n s u l i n - d e p e n d e n t status, a t test f o r i n d e p e n d e n t s a m p l e s was c o n d u c t e d ; n o d i f f e r e n c e s w e r e o b s e r v e d b e t w e e n i n s u l i n - d e p e n d e n t ( M = 18.5; S D = 4.0) a n d n o n - i n s u l i n d e p e n d e n t s u b j e c t s [ M = 19.0, S D = 3.9; t(187) = .849, p > .35]. T h e r e f o r e , d a t a f r o m b o t h s u b j e c t g r o u p s w e r e c o m b i n e d f o r s u b s e q u e n t analyses.
Internal Conshstency. T h r e e p r o c e d u r e s w e r e c o m p l e t e d to d e t e r m i n e the internal consistency of the ADS. First, item analyses revealed acceptable i t e m - r e m a i n d e r c o r r e l a t i o n s (see T a b l e I). S e c o n d , C r o n b a c h ' s (1951) c o e f f i c i e n t a l p h a was d e t e r m i n e d to b e .73 a n d r e p r e s e n t s t h e l o w e r b o u n d f o r t h e Table II. Ranges, Means, Standard Deviations, and Correlations of All Meas-
ures with the Apprisal of Diabetes Scale (ADS) Measure
Correlation with ADS
ADS DRAQ-R HbAlc DHBQ-R (Severity) DHBQ-R (Susceptibility) PSS DDHS (Severity) PSI (Anxiety) PSI (Anger) PSI (Depression)
8-31 0-45 4.8-14 6-25 0-20 0-9 7-167 0-27 0-12 0-41
18.65 24.87 8.35 20.63 9.71 4.33 69.70 8.32 4.61 8.22
4.04 8.19 1.77 4.13 5.82 2.64 28.40 5.55 3.16 5.57
.17" .18'* .31"* .42*** .49*** .59*** .55*** .39*** .58***
aLow scores on all scales represent positive health status. All tests are onetailed; N = 102 for all analyses except for HbAlc (N = 195). *p < .05. **p < .01. ***p < .001.
test's true reliability. Finally, a principal components analysis was conducted to evaluate whether the ADS reflects an underlying, unidimensional factor. A single component with an eigenvalue of 2.73 emerged. Examination of the Scree plot indicated no noteworthy discontinuity among the remaining eigenvalues, thereby supporting the decision to retain a single factor which accounted for 39% of the variance. Loadings on this factor ranged from 1.424[ to 1.7521 (see Table I). Taken together, these three analyses indicate that the ADS assesses an internally consistent dimension of diabetes appraisal. Stability. Pearson product-moment correlations for the 1-hr retest, r(95) = .89, and for the 1-week retest, r(77) = .85 (both p s < .0001), suggest that the ADS is stable over repeated administrations. Validity
Validity of the ADS was determined by calculating Pearson product-moment correlations between the ADS and each of the other measures used in this study. Summary statistics for all measures, and results of the correlational analyses are presented in Table II. All correlational analyses were one-tailed because of the a priori nature of our hypotheses. In this regard, we expected the ADS to be positively correlated with measures of negative affect, perceived stress, diabetes-related hassles, perceived severity of and susceptibility to diabetes, diabetic nonadherence, and poor glycemic control. The results of the correlational analyses indicate a strong relationship between scores on the ADS and (a) the PSI [rs(100) = .55, .39, and .58 for anxiety, anger, and depression, respectively], (b) the PSS [r(100) = .49], and (c) the DDHS [r(100) = .59], Thus, higher levels of negative appraisal were associated with higher levels of anxiety, anger, depression, perceived stress, and diabetes-related hassles. Moderate relationships were found between the ADS and the DHBQ-R subscales [rs(100) = .31 and .42 for severity and susceptibility, respectively]. These results indicate that individuals reporting a negative appraisal of their disease were more likely to describe themselves as susceptible to their diabetes, which they perceived as a severe disease. Finally, a modest relationship was observed between the ADS and both the DRAQ-R [r(100) = . 17] and glycosylated hemoglobin [r(193) = . 18]; these findings suggest that individuals reporting negative appraisal were less likely to adhere to their diabetic regimen and more likely to be experiencing poorer glycemic control during the previous 8 weeks. DISCUSSION The findings obtained in this study establish the reliability of the ADS, a self-report measure of an individual's appraisal of diabetes. ADS scores
Appraisal of Diabetes Scale
represent an internally consistent, unidimensional measure of appraisal, as determined by item and factor analytic methods as well as use of Cronbach's coefficient alpha. This level of internal consistency can be considered unusually high given the brevity of the scale. The ADS was also reliable over separate administrations, suggesting that it measures a relatively stable appraisal process. Evidence for the validity of the ADS was also obtained. ADS scores were strongly associated with measures of psychological adjustment and current stress and moderately associated with health beliefs about the perceived severity of diabetes and its complications and about the perceived susceptiblity to diabetic complications. Significant but modest relationships were observed between scores on the ADS and self-reported diabetic adherence and objectively measured glycemic control. The modest relationship between appraisal and self-reported adherence is somewhat surprising. In contrast, the modest relationship between the ADS and glycemic control was not unexpected; indeed, given the many potential influences upon glycemic control, the emergence of any relationship between appraisal and glycosylated hemoglobin is noteworthy. We wish to emphasize, however, that this relationship is only correlational. Thus, it is equally possible that poor diabetic control is responsible for negative appraisal. Prospective, longitudinal research employing causal modeling techniques is needed to clarify the nature of this relationship. Overall, the pattern of our findings provides initial support for the reliability and validity of the ADS. Given that these findings were obtained with a brief instrument, and in a relatively homogeneous sample (with respect to age, gender, race, duration of diabetes, etc.), they can be considered robust. Additional research is required to establish the ADS's psychometric properties with different patient groups. In addition to its psychometric qualities, the ADS has several important practical strengths. First, it can be administered by nonprofessional support staff; it is easy to score and interpret. Second, most patients will find it easy and quick to complete, requiring 5 min or less. For illiterate or visually impaired individuals, it can be read to them easily. Third, the instrument has "face validity" and it inquires only about diabetes-related information; thus it will not offend medical patients in the way that more traditional psychological instruments (e.g., the MMPI) may. In this regard, the ADS might prove useful as a brief screening instrument for adjustment to diabetes. Specifically, it could be administered routinely to diabetic patients in order to identify those few who may be currently experiencing, or at risk for, dysphoric reactions and noncompliance problems. For "at risk" persons, a more thorough psychological assessment may be indicated. To enhance our understanding of the ADS, and of the role of apprisal in diabetes, future research might explore (a) the relationships found in the
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current study with other samples (e.g., females, adolescents, etc.); (b) the relationship between appraisal and behavioral indices of diabetic regimen adherence; (c) the predictive validity of the ADS; and (d) whether psychological interventions designed to facilitate more adaptive cognitions (e.g., stress management) can lead to improved appraisal and, perhaps as a result, enhanced psychological and somatic adjustment to diabetes. REFERENCES Brownlee-Duffeck, M., Peterson, L., Simonds, J. F., Goldstein, D., Kilo, C., and Hoette, S. (1987). The role of health beliefs in the regimen adherence and metabolic control of adolescents and adults with diabetes mellitus. J. Consult. Clin. PsychoL 55: 139-144. Cohen, S., Kamarck, T., and Mermelstein, R. J. (1983). A global measure of perceived stress. J. Health Soc. Behav. 24: 385-396. Cox, D. J., Taylor, A. B., Nowacek, B., Holley-Wilcox, P., Pohl, S. L., and Guthrow, E. (1984). The relationship between psychological stress and insulin-dependent diabetic blood glucose control: Preliminary investigations. Health Psychol. 3: 63-75. Cronbach, L. J. (1951). Coefficient alpha and the internal structure of tests. Psychometrika 16: 297-334. Gonen, B., Rachman, H., Rubenstein, A. H., Tanega, S. P., and Horwitz, D. L. (1977). Hemoglobin Alc: An indicator of the metabolic control of diabetic patients. Lancet 2: 734-737. Gong-Goy, E., and Hammen, C. (1980). Causal perceptions of stressful events in depressed and nondepressed outpatients. J. Abnorm. Psychol. 89: 662-669. Hammen, C., and Mayol, A. (1982). Depression and cognitive characteristics of stressful life-event types. J. Abnorm. Psychol. 91: 165-174. Ilfeld, F. W., Jr. (1976). Further validation of a Psychiatric Symptom Index in a normal population. Psychol. Rep. 39: 1215-1228. Kanner, A. D., Coyne, J. C., Schaefer, C., and Lazarus, R. S. (1981). Comparison of two modes of stress measurement: Daily hassles and uplifts versus major life events. J. Behav. Med. 4: 1-39. Wing, R. R., Epstein, L. H., Nowalk, M. P., and Lamparski, D. M. (1987). Behavioral selfregulation in the treatment of patients with diabetes mellitus. Psycho/. Bull. 99: 78-89.
APPENDIX Table A I . Appraisal of Diabetes Scale
People differ in their thoughts and feelings about having diabetes. We would like to know how you feel about having diabetes. Therefore, please circle the answer to each question which is closest to the way you feel. Please give your honest feelings - we are interested in how you feel, not what your doctor or family may think. l.
How upsetting is having diabetes for you? 1
Not at all
Appraisal of Diabetes Scale
Table AI. Continued 2.
How m u c h control over your diabetes do you have? 1
None at all
How much uncertainty do you currently experience in your life as a result of being diabetic? 1
none at all
extremely large amount
How likely is your diabetes to worsen over the next several years? (Try to give an estimate based on your personal feeling rather than based on a rational judgment.) 1
not likely at all
Do you believe that achieving good diabetic control is due to your efforts as compared to factors which are beyond your control? 1
totally because of me
mostly because of me
partly because of me and partly because of other factors
mostly because of other factors
totally because of other factors
How effective are you in coping with your diabetes? 1
not at all
To what degree does your diabetes get in the way of your developing life goals? 1
not at all
extremely large a m o u n t