TheApplicationofPropensityScoreAnalysistoNon-.ppt

The Application of Propensity Score Analysis to Non-randomized Medical Device Clinical Studies: A Regulatory Perspective;Outline;Randomized Trials;Randomized Trials;Nonrandomized Studies and a Potential Problem;Adjustments for Covariates;;Propensity Score Methodology;Propensity Score Methodology (cont.);;;;;;;Matching based on propensity scores (PS) PS Trt A vs. Trt B Compare treatments based on matched pairs Problem: may exclude unmatched patients ;Stratification;;Propensity Score Methods;Practical Issues;Example – Device A;Enrollment Time;Two treatment groups are not comparable Imbalance in multiple baseline covariates Imbalance in the time of enrollment So, any direct treatment comparisons on the effectiveness endpoint are inappropriate. And, p-values from direct treatment comparisons are un-interpretable. What about treatment comparisons adjusting for the imbalanced covariates? Traditional covariate analysis Propensity score analysis ;;Estimated Propensity Scores (with time);Estimated Propensity Scores (w/o time);;;;Example: Device B ;; ;Table 2. Distribution of patients at five strata;Estimated Propensity ScoresN(new)=560, N(control)=290;;After adj. balance check:;Percentage of patients with prior Mi;;Study Design;Limitations;Limitations;Conclusions;References;References;