Variation in diabetes care quality among medicare advantage plans: understanding the role of case mix

Abstract

This study investigates whether variation in Medicare Advantage plan performance on comprehensive diabetes care is explained by the case mix of plans. Using data on 513 Medicare Advantage plan-year observations for 2007 and 2008, the authors estimate multivariate regressions for 3 diabetes care quality measures: (1) hemoglobin screening, (2) low-density lipoprotein screening, and (3) retinal eye exam. Plan case mix is measured with the percentage of a plan's enrollees who have type 1 diabetes with and without comorbidities and the percentage of a plan's enrollees who have type 2 diabetes with and without comorbidities. Plans with a higher percentage of enrollees with type 1 diabetes with comorbidity and plans with a higher percentage of enrollees with type 2 diabetes without comorbidity have lower performance, on average. Finding evidence of a relationship between case mix and Healthcare Effectiveness Data and Information Set performance reinforces the argument for developing standardized risk adjustment or stratification methods in public reporting and pay-for-performance efforts.