Background
The inverse correlation between the complexity of a drug regimen and medication adherence is well established. Fixed-dose
combination (FDC) therapies are hypothesized to enhance compliance by decreasing the number of required pills.
Objective
The objective of the study is to compare adherence of a FDC [Glucovance®, a FDC of metformin and glyburide] to a 2-pill regimen.
Design
Longitudinal data from a large claims database were used to assess adherence from January 1, 2000, to December 31, 2001. Propensity
scoring methods were used to mitigate concerns related to non-random assignment of patients to treatments.
Subjects
The subjects of the study were individuals prescribed metformin or sulfonylurea or both before July 2000, who were prescribed
both metformin and sulfonylurea concurrently (either separately or FDC) after August 2000.
Measurements
Adherence was measured by medication possession ratio; the proportion of days on which a patient had medication available.
Results
The FDC enhanced adherence rates by approximately 13% when compared to a 2-pill regimen.
Conclusions
Compared to 2-pill therapy, a FDC resulted in important increases in patient adherence. Economic analyses are warranted to
determine whether the clinical benefits attributable to the adherence gains are worth the incremental cost of a FDC.
Key words adherence - fixed-dose combination drugs - prescription medications