Background: Missing participant data (MPD) can bias trial results and conclusions if the missingness is associated with the occurrence of the outcome of interest. No study has summarized the reporting and analytic approaches of MPD that authors have used for continuous outcomes in randomized controlled trials (RCTs).
Objective: Our objectives are to assess: 1) how authors report MPD for continuous outcomes; 2) the analytic methods used for primary analysis and sensitivity analysis to address MPD; and 3) the impact of these sensitivity analyses on the conclusions.
Method: We are conducting a systematic survey of RCTs published in 2014 in core medical journals. We include RCTs reporting at least one patient-important outcome analyzed as a continuous variable. We randomly sample RCTs aiming at a sample size of 200. We will calculate the proportion of RCTs that explicitly reported whether MPD occurred, percentage of randomized participants with MPD for the continuous outcome, the methods used to handle MPD in the primary and sensitivity analyses, and how often the conclusions are interpreted considering the sensitivity analyses conducted and whether consideration of MPD changes the conclusion. We will conduct regression analyses with independent variables general trial characteristics (e.g. type of funding, type of intervention) and methodological trial characteristics (e.g. allocation concealment, length of follow-up), to establish factors associated with reporting, analysis, and conclusions.
Conclusion: Our methodological survey will have important implications for both trialists and users of trial evidence in interpretation of the findings from RCTs with MPD on continuous outcomes.