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Introduction
Chronic kidney disease (CKD) is a common condition in patients with type 2 diabetes (T2DM). An estimated 20–35% of patients with T2DM have moderate to severe renal impairment [1, 2]. However, many antihyperglycemic medications are contraindicated or need to be used with caution in patients with CKD, complicating T2DM treatment choices and management [3]. Patients with T2DM and CKD are particularly susceptible to safety and tolerability issues related to many classes of oral antihyperglycemic agents (OAHA). Dipeptidyl peptidase-4 inhibitors (DPP-4i) such as sitagliptin are well tolerated in a broad range of T2DM patient types, including those with renal disease, and may therefore be preferentially used in patients with CKD. Prior studies have demonstrated the preferential use of sitagliptin in several populations [4–7]. In general, patients initiating treatment with sitagliptin were older and had more complications of diabetes and comorbidities than patients initiating other antihyperglycemic therapies [4–7]. If not recognized and appropriately considered in the analysis, this preferential selection of patients with specific demographic and disease characteristics for treatment with sitagliptin (channeling bias) could lead to inaccurate treatment effect estimates in comparative analyses that include sitagliptin [8]. The objective of this study was to describe the baseline characteristics of patients with T2DM and CKD initiating treatment with sitagliptin or non-DPP-4i OAHAs to ascertain whether channeling exists in this patient population.
Methods
The Truven Health MarketScan® Databases (MarketScan, Truven Health Analytics, Ann Arbor, MI, USA) contain medical claims records for more than 150 million unique patients dating from 1996. The records are derived from outpatient and inpatient insurance claims for employees of over 100 employers participating in more than 12 health plans, and their beneficiaries in the United States. Records consist of commercial claims and healthcare encounters, including information on demographics, health plan membership, International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, and Current Procedure Terminology (CPT) codes. The records of retirees with supplemental insurance are included in the database thus providing data on the elderly with continuity of care across those <65 and ≥65 years of age.
Patients ≥25 years of age with T2DM and CKD, with claims in the United States (US) between January 2006 and June 2012, were identified in MarketScan. Of these patients, those initiating sitagliptin or a non-DPP-4i...