Health Care Utilization and Costs in Type 2 Diabetes Mellitus and Their Association with Renal Impairment

Abstract

Objective: To evaluate the health economic burden of renal impairment (RI) in patients with type 2 diabetes mellitus (T2DM). Methods: This retrospective analysis used medical and pharmacy claims and outpatient laboratory data from a large US health care plan (January 1, 2004 to December 31, 2008). Patients with T2DM aged ≥ 18 years with continuous enrollment for ≥ 12 months pre- and post–index date (defined as date of first evidence of T2DM) who had ≥ 1 serum creatinine (SCr) laboratory test in pre- and post–index periods were included. Renal impairment prevalence was determined by laboratory data and compared with prevalence of RI identified from claims (physician–diagnosed). Renal impairment stages were categorized using estimated glomerular filtration rate. Multivariate analyses were conducted to examine association between pre–index RI status and post–index total diabetes–related health care costs. Results: Of 82 263 patients with T2DM with post–index SCr laboratory values, 34.4% had RI as evidenced by laboratory data, while 11.9% had RI using claims–based criteria. The prevalence as determined from laboratory data was roughly 3 times higher than the prevalence determined from claims data, probably due to under–recognition and under–diagnosis by providers. Compared with patients without pre–index RI, patients with RI were more likely to incur ≥ 1 diabetes–related ambulatory visit (88.8% vs 85.2%; P < 0.001), emergency room visit (7.2% vs 4.5%; P < 0.001), and inpatient stay (13.8% vs 6.6%; P < 0.001) during the 12-month post–index evaluation period. Patients with pre–index RI incurred 41.8% higher post–index total diabetes–related health care costs compared with no RI (odds ratio, 1.42 [CI, 1.29–1.56]; P < 0.001). Compared with no RI, insulin–related health care costs were independently associated with increases of 37.4% (mild RI), 166.8% (moderate RI), 408.3% (severe RI), and 343.8% (end–stage RI). Conclusion: Renal impairment in T2DM is associated with high health care utilization and costs.