Disease-specific quality-of-life measures as predictors of mortality in individuals living with type 2 diabetes.

OBJECTIVE The aim of this study was to examine whether disease-specific quality-of-life measures are independent predictors of mortality in patients with type 2 diabetes. METHODS A cohort of 420 patients with type 2 diabetes was recruited from the outpatient clinic of a medical center. At baseline, the disease-specific measure of the Diabetes Impact Measurement Scales (DIMS) and clinical and biological marker variables were measured. The DIMS domains included symptoms, diabetes-related morale, social role fulfillment, and well-being. Complications consisted of stroke, heart disease, visual impairment, amputations, kidney disease, cognitive impairment, and incontinence. Mortality data were collected from the national mortality register using personal identification numbers. Multivariate Cox proportional hazards models were used. RESULTS The overall mortality rate was 10.9%. The DIMS scales of symptoms and well-being and the total score were significantly associated with mortality, independent of age, gender, glucose control, and complications. When the scales of the DIMS were simultaneously considered, only symptom and social role fulfillment of the DIMS exerted a significant effect on mortality. Patients in the categories of the second and third quartiles (worse status) had significantly increased risk compared with those in the category of the fourth quartile (best status) [for the symptom scale: RR = 13.10, 95% confidence interval (CI) = 2.75-62.50 and RR = 5.49, 95% CI = 1.50-20.09, respectively; for the social role fulfillment scale: RR = 6.18, 95% CI = 1.10-34.87 and RR = 6.53, 95% CI = 1.40-30.57, respectively]. CONCLUSION Our data suggest that the unique contribution of health-related quality of life to mortality was independent of objective health measures, such as glucose control and complications.