Evaluation of the association between the EQ-5Dindex (health-related utility) and body mass index (obesity) in hospital-treated people with Type 1 diabetes, Type 2 diabetes and with no diagnosed diabetes

Aims: The purpose of this study was to characterize the impact of body mass index (BMI) on health-related utility for patients with Type 1 and Type 2 diabetes and those without diabetes. Methods: The study was conducted in Cardiff and the Vale of Glamorgan, Wales, UK. Health-related utility was measured using the EQ-5Dindex. Patients from the Health Outcomes Data Repository (HODaR) were surveyed by postal questionnaire either 6 weeks post discharge for in-patients or at out-patient clinics between January 2002 and July 2003. BMI was calculated from self-reported data within the survey. Patients with diabetes were identified by a previous history of an in-patient admission with diabetes or as an out-patient with diabetes recorded as a coexisting diagnosis. Results: Questionnaires were returned from 27 924 patients of whom 2575 had diabetes. Increasing BMI was found to reduce utility in all three groups. BMI was significantly greater for those with Type 2 diabetes compared with those with Type 1, and those without diabetes (P < 0.001). Multiple regression analysis demonstrated that both BMI and diabetes status had a significant effect on utility. However, the rate of change of utility attributable to BMI was not found to be significantly different between the various groups. Conclusions: Obesity negatively impacts upon health-related utility and thus quality of life for all patient groups. There was no significant difference in the effect of obesity on utility between those with and without diabetes