Objectives: Diabetes patients suffer from comorbid conditions and disease-related complications. Combined with demographic, clinical and treatment satisfaction variables, they have a confounding effect on health-related quality of life (HRQoL). This study compared the sensitivity of EQ-5D, SF-6D and 15D utilities to the specific effect of diabetes complications.
Methods: Utilities were compared in 319 type II diabetics with and without comorbidities and complications. Based on subsample size and confirmed diagnoses, coronary heart disease (CHD) and diabetic retinopathy (DR) were two complications chosen for further analysis. Significant EQ-5D, SF-6D and 15D predictors were identified with OLS regression and subsequently controlled for with ANCOVA.
Results: The presence of CHD resulted in utility decrements (P < 0.001) for all instruments, whereas DR only decreased 15D utilities (P < 0.05). Gender, age, treatment satisfaction, arthropathy and diabetic foot were significant predictors throughout, whereas BMI, neuropathy and CHD for at least two utilities. After controlling for these confounding variables, 15D still discriminated between diabetics with and without CHD (P < 0.01) and DR (P < 0.05), with seven and five dimensions affected, respectively.
Conclusions: After removing the effect of background variables, 15D utilities remain sensitive to CHD and DR. The obvious explanation is its richer descriptive system, which provides increased discriminative ability compared to EQ-5D and SF-6D, and this might be evidence for preferring the 15D in economic evaluations of interventions for diabetics. However, the need remains for further testing in other diabetes complications and more diverse patient samples.