Category: Professional Posters
Purpose: Although metformin is recommended as the ﬁrst-line therapy in the guidance document from the American Diabetes Association, Japanese clinical guidelines do not guide the physician on the application of specific oral hypoglycemic agents to drug naïve patients. In Japan, dipeptidyl peptidase-4 (DPP-4) inhibitors are often prescribed for patients newly diagnosed with type 2 diabetes mellitus (T2DM) because of the low incidence of side effects. However, our previous study revealed that metformin was underused. This study examined the prescribing patterns of DPP-4 inhibitors and metformin in drug-naïve patients with T2DM and evaluated factors affecting initiation of DPP-4 inhibitors versus metformin.
Methods: The study was approved by the Institutional Review Board of the Kitasato University Hospital (KUH), Japan. A retrospective chart review of drug-naïve patients with T2DM was conducted at KUH between January 1, 2015 and July 31, 2017. Patients older than 20 years who newly started DPP-4 inhibitors or metformin monotherapy were included in the study. Data was collected from electronic medical records. The outcomes evaluated included the utilization patterns of DPP-4 inhibitors and metformin, and baseline patient factors that were associated with the selection of the agents. Multivariable logistic regression models were built to identify baseline patient factors associated with initiation of DPP-4 inhibitors versus metformin. Patient characteristics including sex, age, Body Mass Index (BMI), smoking, alcohol, and estimated glomerular filtration rate (eGFR), were used as the predictor variables in univariate analysis; multivariate analysis was performed using factors with p-value less than 0.2 and the odds ratio (OR) calculated. The univariate analysis was performed to identify predictive factors for attaining hemoglobin A1c levels less than 7.0 percent after three months of treatment initiation. In addition, we examined the selection of either DPP-4 inhibitors or metformin based on combinations of the following three factors: age equal to or greater than 65, BMI, and eGFR. The Kaplan-Meier method was used to compare treatment intensification or discontinuation period of the two treatment groups using the log-rank test.
Results: A total of 110 patients were enrolled (68.2 percent males, 31.8 percent females). Of these, 79 (71.2 percent) were prescribed DPP-4 inhibitors and 31 (28.2 percent) were prescribed metformin. The mean age was 69 and 50 years in the DPP-4 inhibitor and metformin groups, respectively (p-value less than 0.001). The mean BMI was higher in the metformin group than in the DPP-4 inhibitor group (28.2 vs. 23.1, p-value less than 0.001). Moreover, the mean eGFR was higher in the metformin group than in the DPP-4 inhibitor group (89.0 vs. 64.3, p-value less than 0.001). Patient factors associated with DPP-4 inhibitors selection over metformin were age equal to or greater than 65 years (p-value less than 0.001, OR equals 12.34) and BMI less than 25 kg/m2 (p-value less than 0.001, OR equals 3.11). None of the factors were associated with attaining HbA1c less than 7.0 percent. Selection rate of DPP-4 inhibitors based on combinations of the three factors were: three (94.4 percent), two (100.0 percent), one (55.6 percent), and zero (36.4 percent). The Kaplan-Meier curves for the rate of treatment intensification or discontinuation period indicated initial selection of DPP-4 inhibitor or metformin was not associated with the period of treatment continuation.
Conclusion: DPP-4 inhibitors over metformin were initiated in more than double the patients. However, initial selection of either DPP-4 inhibitors or metformin was not associated with achieving the target goal of 7.0 percent HbA1c after three months and treatment continuation. Factors significantly associated with selection of DPP-4 inhibitors over metformin were age greater than 65 years and lower BMI. There was great variability in initiating DPP-4 inhibitors among patients with zero or one factor. Identifying those factors may help pharmacists promote rational selection of initial therapy.