Comparison of diabetes-associated secondary healthcare utilization between alternative oral antihyperglycaemic dual therapy combinations with metformin in patients with type 2 diabetes: an observational cohort study.

AIMS

To compare diabetes-associated secondary healthcare utilization in patients with type 2 diabetes (T2DM) prescribed sulphonylureas (SUs) versus other oral antihyperglycaemic agents (OHAs) as an add-on to metformin monotherapy (metformin + SU vs metformin + OHA).

METHODS

This retrospective cohort study used data from the Clinical Practice Research Datalink linked to Hospital Episode Statistics. Adults with T2DM initiated on metformin + SU or metformin + OHA from April 2003 to March 2012 were identified. Patients were matched using propensity scores. Diabetes-associated secondary healthcare visits were counted from >6 months post-initiation of dual therapy until treatment change or end of follow-up. Outcomes were calculated as rate ratios, adjusted for over-dispersion using negative binomial regression and propensity score for covariates.

RESULTS

After propensity score matching, 1704 patients were included in each cohort. For the primary objective (diabetes-associated inpatient and outpatient visits combined), the metformin + SU cohort had a directionally higher rate of diabetes-associated secondary healthcare utilization than the metformin + OHA cohort [adjusted rate ratio 1.12, 95% confidence interval (CI) 0.97-1.29]. For the secondary outcomes, the adjusted rate ratio was 1.38 (95% CI 0.95-2.00) for inpatient admissions and 1.10 (95% CI 0.95-1.28) for outpatient visits. Macrovascular complications, accounting for 77.2% of inpatient admissions, occurred at a statistically significantly higher rate in the metformin + SU cohort than in the metformin + OHA cohort (adjusted rate ratio 1.77, 95% CI 1.15-2.71).

CONCLUSIONS

This study found a statistically significant higher rate of inpatient admissions for macrovascular complications and cardiology outpatient visits and, overall, a directionally higher rate of secondary healthcare utilization for patients prescribed metformin + SU than for those prescribed metformin + OHA. This adds to the evidence that long-term and health economic outcomes should be considered in treatment decisions for patients with type 2 diabetes.