Differences in baseline characteristics between patients prescribed sitagliptin versus exenatide based on a US electronic medical record database.

INTRODUCTION: Sitagliptin, an oral dipeptidyl peptidase-4 inhibitor, and exenatide, an injectable glucagon-like peptide-1 receptor agonist, are incretin-based therapies for the treatment of type 2 diabetes. This study examined differences in baseline characteristics between patients with type 2 diabetes initiating sitagliptin vs. exenatide treatment in clinical practice settings in the US.
METHODS: The General Electric Healthcare's Clinical Data Services electronic medical records database, covering 12 million US patients of all ages from 49 states, was used to identify patients with type 2 diabetes, aged > or =30 years, who received their first sitagliptin or exenatide prescription between October 1, 2006 and June 30, 2008 (index period). Patient's medical records, including demographics, diagnoses, procedures, prescriptions, and laboratory results were extracted for the 12-month period (baseline) prior to the date of the first prescription of sitagliptin or exenatide (ie, the index date). Patient baseline profiles were stratified by mono-, dual, or triple therapy and compared between regimens with sitagliptin or exenatide.
RESULTS: A total of 9543 patients initiated therapy with sitagliptin (n=5589) or exenatide (n=3954) during the index period. For those initiating monotherapy, 876 patients initiated sitagliptin and 476 initiated exenatide. Compared with patients initiating exenatide at baseline, patients on sitagliptin were older (64 vs. 55 years), more likely to be men (45% vs. 35%), and less likely to be obese (60% vs. 87%), and had higher hemoglobin A(1c) (HbA(1c); 7.1% vs. 6.9%), a higher serum creatinine (1.2 mg/dL vs. 1.0 mg/dL), and a higher prevalence of pre-existing cardiovascular complications or microvascular conditions (all P<0.01 for sitagliptin vs. exenatide). For dual therapy, 1885 were prescribed sitagliptin and 1392 were prescribed exenatide. For triple therapy, 2828 were prescribed sitagliptin and 2086 were prescribed exenatide. The observed patient profile differences with dual and triple therapy were generally consistent with those observed with monotherapy.
CONCLUSION: In a clinical practice setting, there are differences in the baseline characteristics of patients with type 2 diabetes who are prescribed sitagliptin relative to those prescribed exenatide. These findings have important implications for conclusions drawn from observational studies using medical record or claim databases, as estimated clinical and health outcomes measures may be biased due to channeling of patients to different therapies based on different baseline characteristics.