Baseline characteristic differences between patients prescribed sitagliptin vs. other oral antihyperglycemic agents: analysis of a US electronic medical record database.

AIMS: This study examined the relationship of baseline characteristics and medication use in patients with type 2 diabetes who were prescribed sitagliptin versus other oral antihyperglycemic agents in clinical practice settings in the United States.
METHODS: The General Electric Healthcare's Clinical Data Services electronic medical record (EMR) 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, metformin, sulfonylurea, or thiazolidinedione prescription between October 2006 and June 2008 (index period) as part of new mono-, dual, or triple therapy regimens. Patient demographics, diagnoses, prescriptions, and laboratory results were extracted for the 12-month period (baseline) prior to the index date (i.e., date of first prescription). Data were stratified by mono-, dual, or triple therapy and compared between sitagliptin regimens and non-sitagliptin regimens with other oral agents (metformin, sulfonylureas, or thiazolidinediones). Adjusted logistic regression analyses were used to estimate odds ratios (OR) associated with prescribing sitagliptin versus other oral monotherapy in relation to patient baseline characteristics.
RESULTS: Among 41,836 patients new to oral monotherapy, 876 (2.1%) received sitagliptin. Compared to patients initiating non-sitagliptin monotherapy, patients on sitagliptin monotherapy were older (64 vs. 60 years) and had lower body mass index (33 kg/m(2) vs. 34 kg/m(2)), higher serum creatinine (1.2 vs. 1.0 mg/dL), higher prevalence of chronic renal disease (7.2% vs. 1.9%), greater use of lipid-lowering agents (42% vs. 38%), and higher prevalence of cardiovascular conditions (CVD: 12.7% vs. 8.3%) and microvascular complications (MVD: 13.4% vs. 5.8%) (all p < 0.05). Of 22,683 patients new to dual therapy, 1885 (8.3%) were on sitagliptin regimens. Relative to patients on non-sitagliptin dual therapy regimens, patients prescribed sitagliptin as part of dual therapy regimens were older and had higher serum creatinine, higher prevalence of CVD, MVD, or chronic renal disease, and greater use of lipid-lowering and antihypertensive agents (all p < 0.05). Among 9967 patients new to triple therapy, 2828 (28.4%) were on triple therapy regimens with sitagliptin. Relative to patients on non-sitagliptin triple therapy regimens, patients on sitagliptin as part of triple therapy regimens were older, and had higher serum creatinine and greater use of antihypertensive or lipid-lowering agents (all p < 0.05). Adjusted logistic regression showed that significant predictors of being prescribed sitagliptin monotherapy were older age (OR 1.01, 95% CI 1.00, 1.02), higher HbA(1c) level (OR 1.10, 95% CI 1.04, 1.17), higher serum creatinine level (OR 1.22, 95% CI 1.08, 1.39), presence of MVD (OR 1.50, 95% CI 1.08, 2.09), and presence of chronic renal disease (OR 2.22, 95% CI 1.41, 3.49). LIMITATIONS: Diabetes care delivered by non-participating physicians is not captured in the GE CDS EMR database and, therefore, the prevalence of the diseases identified based on ICD-9 diagnosis/procedure and CPT codes provided in the Appendix may be underestimated. Duration of diabetes was not consistently recorded and some measures were not available.
CONCLUSION: Patients with type 2 diabetes who were prescribed sitagliptin regimens in clinical practice were older and more likely to have pre-existing co-morbid conditions compared to patients receiving non-sitagliptin regimens with other common oral antihyperglycemic agents. These findings have important implications for observational studies in that estimated clinical and health outcome measures may be biased due to channeling of patients to different therapies based on different baseline characteristics.