Additional analyses and handling of missing data
SECONDARY
Interim data analysis will be conducted once 50% of the overall sample size has been achieved with the purpose of guiding the data monitoring board on recommendations for the study. Missing data will be dealt with as missing covariate and outcome data. As a generalized estimating equations model will be used, missing outcome data will be dealt with using a missing at random assumption. If > 3% of data for covariate data is missing, multiple imputation will be used for the primary analysis. Given the way the adherence rate is computed, we anticipate that there may be a number of ways that the outcome measure could be missing. These include loss to follow-up and or partial information collected at anyone study visit. A further analysis will be performed in which missing primary outcome data will be imputed. Multiple imputation will be also performed on missing covariate and outcome data for all secondary clinical analyses in a similar way to that performed for the primary analysis.