Ilene H. Zuckerman, Euni Lee, Anthony K. Wutoh, Zhenyi Xue, Bruce Stuart Ph.D.
To demonstrate how a relatively underused design, regression‐discontinuity (RD), can provide robust estimates of intervention effects when stronger designs are impossible to implement.
Administrative claims from a Mid‐Atlantic state Medicaid program were used to evaluate the effectiveness of an educational drug utilization review intervention.
Data Sources/Study Setting
A drug utilization review study was conducted to evaluate a letter intervention to physicians treating Medicaid children with potentially excessive use of short‐acting ‐agonist inhalers (SAB). The outcome measure is change in seasonally‐adjusted SAB use 5 months pre‐ and postintervention. To determine if the intervention reduced monthly SAB utilization, results from an RD analysis are compared to findings from a pretest–posttest design using repeated‐measure ANOVA.
Both analyses indicated that the intervention significantly reduced SAB use among the high users. Average monthly SAB use declined by 0.9 canisters per month (<.001) according to the repeated‐measure ANOVA and by 0.2 canisters per month (<.001) from RD analysis.
Regression‐discontinuity design is a useful quasi‐experimental methodology that has significant advantages in internal validity compared to other pre–post designs when assessing interventions in which subjects' assignment is based on cutoff scores for a critical variable.
Data Collection/Extraction Methods