Total and component health care costs in a non-Medicare HMO population of patients with and without type 2 diabetes and with and without macrovascular disease.

BACKGROUND: Type 2 diabetes (T2DM) is one of the most prevalent and costly chronic conditions in the United States. Macrovascular disease (MVD) remains a common and costly comorbidity in T2DM. Understanding the impact of MVD on total health care costs in patients with T2DM is of great importance to managed care organizations (MCOs).
OBJECTIVE: To examine from the perspective of an MCO the impact of MVD on health care costs in patients with T2DM and in a matched comparison group of patients without diabetes.
METHODS: This study involved retrospective analysis of administrative claims (eligibility, pharmacy, and medical) using data from a commercial health maintenance organization population of approximately 700,000 members in an East Coast health plan. Patients were included in this study if they (a) had 2 or more claims for T2DM ( International Classification of Diseases, Ninth Revision, Clinical Modification[ICD-9-CM] codes 250.X0 or 250.X2), or (b) had a prescription drug claim for insulin and a diagnosis of T2DM, or (c) had at least 1 pharmacy claim for an oral glycemic-modifying agent during the 12-month period from January 1, 2003, through December 31, 2003. Patients with 2 or more medical claims for type 1 diabetes (ICD-9-CM codes 250.X1 or 250.X3) were excluded from the study. A random group of comparison patients without diabetes (ICD-9 code 250.xx) were matched on age group and sex. Study patients in these 2 groups were subdivided into 4 groups based on the presence of medical claims with diagnosis codes for MVD (acute myocardial infarction, other ischemic heart disease, coronary artery bypass surgery, percutaneous transluminal angioplasty, congestive heart failure, cerebrovascular accident, peripheral vascular disease, cerebrovascular disease, and peripheral vascular disease). Direct medical costs were aggregated for 12 months after the index date for patients in all 4 groups. Bootstrapping technique was used to compare the health care costs between patients with T2DM and those without diabetes, stratified by MVD status.
RESULTS: A total of 9,059 patients with T2DM were identified and were matched by age group and sex to a random group of patients without diabetes. MVD was present in 26.9% (n=2,441) of patients with T2DM versus 11.3% (n=1,027) of patients without diabetes. Patients with MVD and T2DM were, on average, a year younger than patients with MVD but without diabetes (54.55 vs. 55.55 years, P <0.001). Patients with T2DM but without MVD were nearly the same age as patients with neither diabetes nor MVD (50.44 vs. 50.59 years, P=0.092). The T2DM patients with MVD had average 12-month costs more than 3 times the costs for patients with T2DM but without medical claims with diagnosis codes for MVD--10,450 dollars versus 3,385 dollars, respectively. Pharmacy costs accounted for 29.0% and inpatient hospital costs accounted for 43.9% of total medical costs in T2DM patients with MVD versus 55.0% and 17.3%, respectively, in T2DM patients without MVD. Patients with MVD diagnoses and T2DM had total average medical costs that were 1.7 times the total medical costs for MVD patients without T2DM--10,450 dollars versus 6,090 dollars, respectively.
CONCLUSIONS: The results of this analysis suggest that MVD may triple the total medical care costs in patients with T2DM. These economic consequences would appear to support the importance of interventions intended to prevent macrovascular events in patients with T2DM.