Abstract
BACKGROUND: Type 2 diabetes mellitus (T2DM) affects 25.8 million individuals in the United States and exerts a substantial economic burden on patients, health care systems, and society. Few studies have categorized costs and resource use at the patient level. The goals of this study were to assess predictors of being a high-cost (HC) patient and compare HC T2DM patients with not high-cost (NHC) T2DM patients. METHODS: Using managed care administrative claims data, patients with two or more T2DM diagnoses between 2005 and 2010 were selected. Patients were followed for 1 year after their first observed T2DM diagnosis; patients not continuously enrolled during this period were excluded from the study. Study measures included annual health care expenditures by component (i.e., inpatient, outpatient, pharmacy, total). Patients accruing total costs in the top 10% of the overall cost distribution (i.e., patients with costs > $20,528) were classified as HC a priori; all other patients were considered NHC. To assess predictors of being HC, a logistic regression model was estimated, accounting for demographics; underlying comorbidity burden (using the Charlson Comorbidity Index [CCI] score); diagnoses of renal impairment, obesity, or hypertension; and receipt of insulin, oral antidiabetics only, or no antidiabetics. RESULTS: A total of 1,720,041 patients met the inclusion criteria; 172,004 were HC. The mean (SD) CCI score for HC patients was 4.3 (3.0) versus 2.1 (1.7) for NHC patients. Mean (SD; upper 95% confidence interval-lower 95% confidence interval) annual per-patient costs were $56,468 ($65,604; $56,778-$56,157) among HC patients and $4,674 ($4,504; $4,695-$4,652) among NHC patients. Inpatient care and pharmacy costs were higher for HC patients than for NHC patients. The strongest predictor of being an HC patient was having a CCI score of 2 or greater (odds ratio [OR] = 4.896), followed by a diagnosis of obesity (OR = 2.106), renal impairment (OR = 2.368), and insulin use (OR = 2.098). CONCLUSIONS: High-cost T2DM patients accrue approximately $52,000 more in total annual health care costs than not high-cost T2DM patients. Patients were significantly more likely to be high-cost if they had comorbid conditions, a diagnosis of obesity, or used insulin.