Effect of drug therapy on HEDIS measurements of HbA1c control in diabetes patients.

The purpose of this study was to corroborate an earlier study that explored the relationship between a health plan's Health Plan Employer Data and Information Set (HEDIS) score for glycolated hemoglobin (HbA1c) control in diabetes patients and its utilization of insulin and oral diabetes products. Prescription volumes were tracked for four categories of diabetes drug therapy: analog insulin, human insulin, single-source brand oral products, and multisource generic oral products, for calendar years 2005 and 2006. The prescription shares of each of the four drug categories for each health plan were matched to the health plan's HEDIS measurements of HbA1c control for each year. Univariate and multivariate regression analysis was performed between the health plan's HbA1c -based HEDIS score and its prescription share of each drug category. A favorable and statistically significant (p < 0.01) relationship was found between plan HbA1c HEDIS score and plan prescription share of analog insulin in both 2005 and 2006. The correlation between HEDIS scores and human insulin was not statistically significant. Unfavorable relationships were found between HEDIS scores and both the single-source brand (statistically significant) and the multisource generic oral category prescription shares (not significant). These results corroborate the relationships found in our earlier study, although a cause and effect relationship cannot be confirmed.