Healthy Skepticism Library item: 5062

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Publication type: Journal Article

Zuckerman IH, Lee E, Wutoh AK, Xue Z, Stuart B.
Application of regression-discontinuity analysis in pharmaceutical health services research.
Health Serv Res 2006 Apr; 41:(2):550-63
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1475-6773.2005.00487.x

Abstract:

OBJECTIVE: To demonstrate how a relatively underused design, regression-discontinuity (RD), can provide robust estimates of intervention effects when stronger designs are impossible to implement. DATA SOURCES/STUDY SETTING: Administrative claims from a Mid-Atlantic state Medicaid program were used to evaluate the effectiveness of an educational drug utilization review intervention. STUDY DESIGN: Quasi-experimental design. DATA COLLECTION/EXTRACTION METHODS: A drug utilization review study was conducted to evaluate a letter intervention to physicians treating Medicaid children with potentially excessive use of short-acting beta(2)-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. PRINCIPAL FINDINGS: 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 (p<.001) according to the repeated-measure ANOVA and by 0.2 canisters per month (p<.001) from RD analysis. CONCLUSIONS: 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.

Keywords:
Bronchodilator Agents/administration & dosage Child Drug Utilization Review/methods* Drug Utilization Review/statistics & numerical data* Health Services Research/methods* Health Services Research/statistics & numerical data* Humans Medicaid/statistics & numerical data Physician's Practice Patterns Regression Analysis* Research Support, U.S. Gov't, P.H.S.