1 Diab Comp, 6:101-104
Personalit Traits as Predictors of Good Diabetic P ontrol Donna E. Giles Suzanne M. Strowig Patricia Challis Philip Raskin
ABSTRACT To identify personality characteristics that might contribute to overall good control of type I diabetes mellitus, we used a biological correlate of control, glycosylated hemoglobin Al, values, as a means of selecting patients. Patients with evidence of good control (HbA,, < 7.5%) were compared with patients with evidence of poor control (HbA1, > 10.4%). All patients were administered the
Personality Research Form E. Need for achievement and a socially desirable response style were associated with good glycemic control. This finding is placed in the context of the complexity of health care behaviors required for adequate selfmanagement. (The Journal of Diabetics and Its Complications 6:101-104,1992.)
pears to predict adherence for some aspects of treatment2-7 but does not predict blood glucose levels.5 Moreover, social support may have a negative effect on glycosylated hemoglobin levels in men.6 Discrepancies between patient reports of treatment adherence and clinician beliefs are well recognized. In fact, physician report is the least reliable measure of adherence, with patient report next lowest in reliability.’ To address this unreliability, we chose a biochemical measure of blood glucose control, glycosylated hemoglobin, as a means of determining whether patients had “good’ or “poor” control. Psychological characteristics related to self-care were assessed in these patients to determine which features would provide discrimination. Glycosylated hemoglobin levels represent an integrated biochemical measure of longterm (2-3 months) blood glucose control and provide a reasonable means of assessing psychological characteristics, which are also relatively stable. Our hypotheses were that patients with good control would demonstrate a higher need to achieve,
reatment of insulin-dependent diabetes mellitus is based on a complicated program of dietary guidelines, multiple daily insulin injections, and blood glucose self-monitoring.’ Predicting the likelihood that a given patient with diabetes will adhere to a particular treatment regimen presents a significant clinical challenge. Previous studies of predictors ranging from demographic characteristics through social support to education have resulted in contradictory findings. Social support ap-
Reprint requests to be sent to: Dr. Donna E. Giles, Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O’Hara Street, Pittsburgh, PA 15213. Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (D.E.G), and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas (S.M.S., P.C., P.R.), USA 0 1992 journal of Diabetes and Its Complications
102 GILES ET AL.
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would show a preference for avoiding harm, and would engage in more socially responsive or desirable behavior compared with patients with poor control. MATERIALS
Subjects. Within a 6-month period, consecutive adult patients (~18 years of age) with Type I diabetes mellitus who were treated in research protocols, or in routine clinical practice, in the Department of Internal Medicine at the University of Texas Southwestern Medical Center, were asked to participate in this study. All patients had type I diabetes mellitus for at least 1 year and were known to the attending clinicians (S.S., P.C., P.R.). Marital status, age, and sex were recorded for all patients. Patients who had evidence of uremia, anemia, or abnormal hemoglobin were excluded from the study. Procedures. Patients were administered the Personality Research Form (E version).9 Subjects were required to have hemoglobin Arc (HbAi,) samples drawn within 1 month of completing this test. HbAi, was determined by high performance liquid chromatography as described by Nathan and Raskin.l’ Values of I-&AI, less than 7.5% were defined as low HbAi, and evidence of good diabetic control. Values of I-GA,, greater than 10.4% were defined as high, based on normal control values in our laboratory. The value of 10.4% is twice the upper limit of normal (5.2%) in our laboratory. The Personality Research Form (PRF)9 is a well-standardized true-false test developed to assess personality traits broadly relevant to the functioning of individuals in a wide variety of situations. It focuses primarily upon areas of normal functioning rather than psychopathology. Form E contains 352 items and requires approximately 1 h to complete. There are 20 content scales that measure domains relevant for self-care, such as need to achieve, avoidance of harm, and responsiveness to social demands. A scale measuring tendency to respond in a random and/or insincere way (Infrequency) was used to exclude subjects who may have been responding randomly. The three scales of interest to our hypothesis were: Achievement, Harm Avoidance and Social Desirability. An analysis of variance was conducted to test our hypothesis that these scale scores would be higher for patients with good diabetes control (HbAi, < 7.5%) compared with patients with poor diabetes control (HbAi, > 10.4%). To protect against a type I error, the probability value of 0.02 (0.05 + 3) was used to determine significance. RESULTS Within a 6-month period, 80 adult patients agreed to participate in the study. Three subjects were excluded because they had elevated scores on the PRF Infre-
quency scale or because of an acute psychiatric disorder (major depression) at assessment. From this sample of 77 patients, 42 subjects met inclusion criteria. That is, 22 were identified with low HbAi, values (10.4%) I-IbAi, values. Mean HbAi, values for the low and high groups were 6.5% _+ 0.8% and 12.3% 2 1.6%, respectively. The remaining 35 patients had HbAi, values ranging between 7.5% and 10.4%. Subjects in the intermediate range were not included in the hypothesis-testing analyses. After completing our hypothesis testing, we performed descriptive analysis including this intermediate group. Results of exploratory analyses are presented after planned comparisons. Patients ranged in age from 18 to 66 years. Mean age for the low HbAi, group (33.9 + 10.6 years) was not different from the age for the high HbAi, group (30.4 & 7.8 years). Treatment setting for patients in each group also did not differ (x2 = 0.07, p = NS); 59.1% of the low HbAi, group originated from a research setting compared with 55.0% in the high HbA1, group. Marital status (married/not married) also did not differ between the two groups (x2 = 1.53, p = NS). There was also no significance difference in sex distribution between the groups (x’ = 3.45, p = 0.07). To address our hypotheses, we compared Achievement, Harm Avoidance, and Social Desirability scales in the two groups. Analysis of variance revealed that Achievement (F 1,4o = 5.79, p = 0.02) and Social Desirthe ability (F1.40 = 5.99, p = 0.02) discriminated groups. The scale measuring Harm Avoidance did not discriminate between low and high HbAi, groups (F 1.40 = 0.03, p = 0.86). Mean scale values for the entire PRF-E profile are presented for patients with low and high HbAi, values in Table 1 using standardized scores. No further differences were found. Exploratory analyses comparing patients with HbAI, values in the intermediate range to patients with low and high HbAi, values revealed that patients with intermediate values had Achievement scale scores equivalent to patients with good control, and had significantly higher Achievement scores than patients with poor control (F2,72 = 3.28, p = 0.04; Duncan’s post hoc test, p < 0.05). Patients with intermediate range HbAi, values reported Social Desirability scores that were not different from either group. DISCUSSION We have used a biological index of diabetes control to evaluate personality characteristics potentially related to well-controlled diabetes. Patients with good control endorsed higher need for achievement and reported more socially desirable behavior than patients with
PERSONALITY TRAITS AS PREDICTORS OF CONTROL
] Diab Comp 1992; 6:2
TABLE I. MEAN PERSONALITY
Scale Abasement Achievement Affiliation Aggression Autonomy Change Cognitive Structure Defendance Dominance Endurance Exhibitionism Harm Avoidance Impulsitivity Nurturance Order Play Sentience Social Recognition Succorance Understanding Social Desirability Infrequency
RESEARCH FORM E SCALE SCORES FOR PATIENTS WITH LOW AND HIGH HbAle VALUES HbAic 49.7 54.6 51.3 49.4 43.5 42.4 58.0 52.0 47.6 51.1 50.2 57.2 47.7 54.3 52.6 40.7 43.6 50.5 52.7 47.7 55.6 47.8
< 7.5% * r +* 2 k k k k k -e k * f 5 f ? + 2 + 2 t
8.4 7.6 9.5 7.5 8.9 10.6 7.3 8.0 7.8 11.2 9.9 5.8 8.4 11.1 9.9 11.4 12.7 5.9 9.9 11.0 11.7 6.6
control. Avoidance of harm as measured in the PRF-E did not discriminate between these groups. No other scale, including measures such as autonomy, impulsivity, and endurance, discriminated patients with good control from patients with poor control. Need for achievement and socially responsive behavior represent theoretically meaningful and clinically appealing components of good diabetes control. Need to achieve reflects desire for successful mastery of a cross section of behaviors. In view of the results of this study, assessment of the patient’s success in other aspects of life might be predictive of success in following a diabetes self-care plan. Patients who have demonstrated achievement-oriented behavior throughout life might be most suited to intensive or complex diabetes self-management techniques. Similarly, individuals who respond positively to and who endorse socially desirable behavior may also be more likely to adhere to a diabetes regimen. This personality trait reflects the importance of the patient-clinician interaction and the contribution this relationship makes to maintaining good diabetes control. Factors that might influence treatment adherence, including treatment setting, age, sex, and marital status, were similar between the two groups. Other factors that are difficult to measure could influence differences in metabolic control. The disease may not be mediated easily by personality traits related to selfcare. This position is supported by our finding that poor
HbAr, > 10.4% 45.5 48.1 46.5 54.5 47.4 41.9 57.3 55.2 49.5 47.8 52.7 56.8 48.9 48.4 56.8 44.5 44.1 50.1 49.7 48.5 46.7 49.0
-+ 11.2 k 10.0 + 8.2 If: 10.9 k 10.3 f 8.0 k 5.8 k 7.7 k 10.9 r 7.9 + 7.9 k 11.2 r 9.7 k 9.5 k 9.6 2 10.4 k 12.3 + 10.0 -+ 9.4 -e 11.9 -+ 12.1 + 6.4
1.91 5.79 3.15 3.17 1.68 0.04 0.12 1.68 0.41 1.19 0.80 0.03 0.19 3.36 1.87 1.27 0.01 0.03 1.00 0.05 5.99 0.38
P 0.18 0.02 0.08 0.08 0.20 0.85 0.73 0.20 0.53 0.28 0.38 0.86 0.67 0.07 0.18 0.27 0.92 0.87 0.32 0.83 0.02 0.54
no other traits discriminated our patient groups. Biological substrates, to date unidentified, may distinguish patients with good and poor control such that, despite appropriate self-care attitudes and behaviors, patients with poorer control simply have a more intractable form of the disorder. Our finding that patients with neither “good’ nor “poor” control, those with values in the intermediate range, reported need for achievement and socially desirable behavior comparable with patients with good diabetic control, suggests that “good’ control is mediated by additional factors. Diabetes mellitus, as a disease process, is characterized by a number of factors that make treatment adherence difficult, including long-term treatment***12 and complicated treatment regimens.13 A variety of self-care behaviors must be integrated into daily life on an ongoing basis. Intellectual, motivational, perceptual, interpersonal, and decision-making skills underlie good self-care. l4 Traits examined in this study represent only a limited range of these characteristics. We have used an easily administered, easily ascertained method to screen factors associated with good diabetes control and with adherence to treatment. More studies are needed to help identify individuals who can successfully engage in good self-care behaviors. Identifying patients who can implement selected therapeutic techniques to achieve good glycemic con-
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