Handling missing data in propensity score estimation in comparative effectiveness evaluations: a systematic review

AIM: Even though systematic reviews have examined how aspects of propensity score methods are used, none has reviewed how the challenge of missing data is addressed with these methods. This review there-fore describes how missing data are addressed with propensity score methods in observational comparative effectiveness studies. METHODS: Published articles on observational comparative effectiveness studies were extracted from MEDLINE and EMBASE databases. RESULTS: Our search yielded 167 eligible articles. Majority of these studies (114; 68%) conducted complete case analysis with only 53 of them stating this in the methods. Only 16 articles reported use of multiple imputation. CONCLUSION: Few researchers use correct methods for handling missing data or reported missing data methodology which may lead to reporting biased findings.