Supplementary Tables E1-E3. Propensity score matching versus coarsened exact matching in observational comparative effectiveness research

Supplementary materials – tables:

Table E1a. Characteristics of PSM strategies for comparison one

Table E1b. Characteristics of PSM strategies for comparison two

Table E2a. Coarsening of covariates used in CEM for comparison one

Table E2b. Coarsening of covariates used in CEM for comparison two

Table E3a. Characteristics of CEM strategies for comparison one

Table E3b. Characteristics of CEM strategies for comparison two

Supplementary materials – figures

Figure E1a. Selection process for comparison one

Figure E1b. Selection process for comparison two

Figure E2a. Distribution of baseline covariates by PSM caliper width for comparison one

Figure E2b. Distribution of baseline covariates by PSM caliper width for comparison two

Figure E3a. Distribution of baseline covariates by CEM strategy for comparison one

Figure E3b. Distribution of baseline covariates by CEM strategy for comparison two

Supplementary materials – tables

Table E1a. Characteristics of PSM strategies for comparison one

Table E1b. Characteristics of PSM strategies for comparison two

Table E2a. Coarsening of covariates used in CEM for comparison one

Table E2b. Coarsening of covariates used in CEM for comparison two

Table E3a. Characteristics of CEM strategies for comparison one

Table E3b. Characteristics of CEM strategies for comparison two

Abstract

Aims & Methods: We compared propensity score matching (PSM) and coarsened exact matching (CEM) in balancing baseline characteristics between treatment groups using observational data obtained from a pan-Canadian prostate cancer radiotherapy database. Changes in effect estimates were evaluated as a function of improvements in balance, using results from RCTs to guide interpretation. Results: CEM and PSM improved balance between groups in both comparisons, while retaining the majority of original data. Improvements in balance were associated with effect estimates closer to those obtained in RCTs. Conclusions: CEM and PSM led to substantial improvements in balance between comparison groups, while retaining a considerable proportion of original data. This could lead to improved accuracy in effect estimates obtained using observational data in a variety of clinical situations.