Attrition, missing data, compliance, and related biases in randomized controlled trials of rehabilitation interventions: towards improving reporting and conduct.

Background Attrition, missing data, compliance, and related biases can influence the magnitude of treatment effects in randomized controlled trials (RCTs). It is unclear which items should be considered when reporting and evaluating the influence of these biases in trial reports in the rehabilitation field. Objectives To describe which individual items considering attrition, missing data, compliance, and related biases are included in quality tools used in rehabilitation research. In addition, we aim to determine whether the existing reporting guidelines, such as the CONSORT and its extensions include all relevant items related to these biases when reporting RCTs in the area of rehabilitation. Methods Comprehensive literature searches and a systematic approach to identify tools and items looking at attrition, missing data, compliance, and related biases in rehabilitation were performed. We extracted individual items linked to these biases from all quality tools. We calculated the frequency of quality items used across tools and compared them to those found in the CONSORT statement and its extensions. A list of items to be potentially added to the CONSORT statement was generated. Results Three new tools to assess the conduct and reporting of trials in the rehabilitation field. From these tools, 28 items were used to evaluate the reporting as well as the conduct of trials considering attrition, missing data, compliance, and related biases in the rehabilitation field. However, our team found that some of these items lack specificity in the information required and therefore more research is needed to determine a core set of items used for reporting as well as assessing the risk of bias (RoB) of RCT in the rehabilitation field. Conclusions Although many items have been described by existing tools and the CONSORT statement (and its extensions) that deal with attrition, missing data, compliance, and related biases, several gaps in reporting were identified. It is crucial that future research investigate a core set of items to be used in the field of rehabilitation to facilitate the reporting as well as the conduct of RCTs.