Volume 48 | Number 3 | June 2013

Abstract List

Mujde Z. Erten Ph.D., Bruce Stuart Ph.D., Amy J. Davidoff Ph.D., J. Samantha Shoemaker Ph.D., Lynda Bryant‐Comstock, Rahul Shenolikar


To compare the use of guideline‐recommended prescription medications for diabetes among edicare beneficiaries enrolled in stand‐alone prescription drug plans (s) with edicare dvantage prescription drug plans (s) in the presence of potential selection bias.

Data Sources/Study Setting

Centers for edicare and edicaid ervices' hronic ondition ata arehouse (2006, 2007).

Study Design

Retrospective cross‐sectional comparison of drug use and proportion of days covered () for oral‐antidiabetics, ‐inhibitors/s, and antihyperlipidemics among and enrollees with diabetes. We estimated “naïve” regression models assuming exogenous plan choice and two‐stage residual inclusion (2) models to study endogeneity in choice of Part D plan type.

Data Collection/Extraction Methods

We identified 111,290 diabetics based on ‐9 codes in edicare claims from a random 5 percent sample of edicare beneficiaries in 2005 excluding dual eligibles.

Principal Findings

The naïve regression models indicated lower probability of drug use for oral‐antidiabetics (−4 percent;  < .001) and ‐inhibitors/ (−2 percent;  = .004) among enrollees, but their was higher (3–5 percent) for all drug classes ( < .001). 2 models produced no significant differences in any‐use equations, but significantly higher values for enrollees for oral‐antidiabetics and ‐inhibitors/s.


We found similar overall use of recommended drugs in diabetes treatment and no consistent evidence of favorable or adverse selection into s and s.