Abstract
In an earlier analysis, differences in health-care costs, medication adherence, and persistence were examined between patients with type 2 diabetes, enrolled in the North Carolina Medicaid, who had newly started thiazolidinedione (TZD) therapy and those starting other oral antidiabetic agents. In this analysis, the size of the cohort was increased by including 18 months of additional Medicaid data (until December 2004) and sought to: (1) replicate the results of the original study in a larger cohort; and (2) extend the original analysis by providing an additional 18 months of observational follow-up.
A total of 2660 patients newly starting TZD therapy between July 2001 and December 2003 were compared to 2050 patients starting other oral antidiabetic medication for health-care costs and outcomes in the post-medication start year. In addition, the initial cohort was followed for an additional 18 months to examine if there were any differences in outcomes, such as hospitalization and total health-care costs, that could be associated with the type of therapy. Multivariate regression techniques, incorporating health-care utilization in the year prior to start of new therapy, were used to determine the net cost impact of one therapy versus the other.
Multiple regression analyses found that patients starting TZD have better treatment persistence in the post-medication start year compared to patients starting other oral antidiabetic agents (4% increase in therapy persistence index, p < 0.001). In addition, patients starting TZDs had 18.9% lower total annual health-care costs (p < 0.01) compared to patients starting other oral antidiabetic agents. Examination of the original cohort of 3191 patients, for up to an additional 18 months, showed TZD's association with improved adherence rates but not with persistence. Importantly, treatment adherence remained the strongest independent predictor of decreased hospitalization risk and health-care cost reduction in this population.
Introduction of thiazolidinedione therapy in a Medicaid-enrolled type 2 diabetic population was associated with significantly greater treatment adherence, in the post-start year, compared to patients starting other oral antidiabetic agents.