Characteristics of patients prescribed sitagliptin and other oral antihyperglycaemic agents in a large US claims database

Abstract

Non-randomised comparative studies of pharmacological agents can be biased because of differences in baseline demographics, medical history and health status of patients prescribed different therapies. Characteristics of patients with type 2 diabetes mellitus (T2DM) taking sitagliptin were compared with patients taking other oral antihyperglycaemic agents (OAHA) in a large US insurance claims database. Using the United Health Care database, we identified T2DM patients with at least one OAHA prescription, and at least 1 year prior enrollment. Patients were classified into subcohorts including sitagliptin or other OAHA, add-on to monotherapy, and triple or more therapy. Comorbidities 12 months before the first OAHA prescription in study window were based on ICD-9 diagnostic codes and NDC codes for prescriptions. Prevalence of comorbidities was consistently higher for patients with sitagliptin prescriptions across most comorbidities (p < 0.05 for 20 of 30 assessed comorbidities). Overall, baseline differences were apparent (p < 0.0001) for retinopathy (5.7% vs. 3.4%), renal failure (5.1% vs. 2.6%), proteinuria (2.8% vs. 2.0%), hypertension (76.9% vs. 68.2%), congestive heart failure (3.4% vs. 2.6%), myocardial infarction (18.0% vs. 14.4%) and chronic neurological conditions (8.1% vs. 6.6%). Differences were most pronounced for initial monotherapy subcohorts. A higher proportion of sitagliptin users had prescriptions for cardiovascular medication (84.2% vs. 74.9%). Sitagliptin users had higher proportions of comorbidities and greater use of prescription medications and physician visits. Researchers should be aware that sitagliptin is prescribed to patients with seemingly worse health status. Ability to analyse observational, non-randomised studies may be limited by substantial differences in patient characteristics between different treatments.