Using the EQ-5D index score as a predictor of outcomes in patients with type 2 diabetes

Objective: To examine whether index scores based on the EQ-5D, a 5-item generic health status measure, are an independent predictor of vascular events, other major complications and mortality in people with type 2 diabetes and to quantify the relationship between these scores and future survival. Subjects: Five-year cohort study involving 7348 patients with type 2 diabetes, aged between 50-75 years who had been recruited to the FIELD (Fenoflbrate Intervention and Event Lowering in Diabetes) study from Australia and New Zealand. Measures: Multivariate Cox proportional hazard regression models were used to estimate the hazard ratio associated with index scores derived from the EQ-5D on: (1) cardiovascular events (including coronary heart disease event, stroke, hospitalization for angina, or cardiovascular death); (2) other major diabetes-related complications (heart failure, amputation, renal dialysis, and lower extremity ulcer); and (3) death from any cause. Life table methods were used to derive expected survival for patients with different index scores. Results: After adjusting for standard risk factors, a 0.1 higher index score (derived from the UK algorithm) was associated with an additional 7% (95% CI: 4-11%) lower risk of vascular events, a 13% (95% CI: 9-17%) lower risk of complications, and up to 14% (95% CI: 8-19%) lower rate of all-cause mortality. Conclusions: Index scores derived from the EQ-5D are an independent predictor of the risk of mortality, future vascular events, and other complications in people with type 2 diabetes. This should be taken into account when extrapolating health outcomes such as quality-adjusted life years (QALYs).