The impact of cardiovascular disease on medical care costs in subjects with and without type 2 diabetes.

OBJECTIVE We examined whether cardiovascular disease (CVD) affects medical care costs differently in subjects with and without diabetes and explored the impact of CVD on costs across the dimensions of age and diabetes duration. RESEARCH DESIGN AND METHODS We compared the prevalence of CVD and medical care costs for subjects with and without CVD in all 16,180 full-year health maintenance organization members in 1999 who had been diagnosed with type 2 diabetes and in control members matched by year of birth and sex. We ascertained diagnoses from the Kaiser Permanente Northwest Region's electronic ambulatory medical record and from hospital discharge datafiles. Utilization from these and other data systems were multiplied by unit costs. RESULTS CVD was 76% more prevalent in subjects with diabetes, but the risk ratios of more severe forms of CVD were even greater. Risk ratios for CVD were greatest in younger subjects. Cost profiles for subjects with both CVD and diabetes differed markedly from those with diabetes but without CVD. In the latter group, costs grew steadily with age, whereas in the former group, costs peaked in the 55- to 64-year age group before declining with age. CONCLUSIONS The types of CVD present in diabetic patients are more likely to be more severe and therefore more costly than in similar subjects without diabetes. CVD also disproportionately affects younger diabetic subjects. Finally, when CVD is present in diabetes, more costs occur earlier in life as well as earlier in the course of diabetes.