Missing data and sensitivity analyses
EVENT
Every attempt will be made to collect full follow-up data on all trial participants; it is thus anticipated that missing data will be minimal. Participants with missing primary outcome data will not be included in the primary analysis in the first instance. This presents a risk of bias, and sensitivity analyses will be undertaken to assess the effect of any missing data. In brief, this will include a multiple imputation approach, using important variables to predict the near FH SDS and a last observation carried forward (LOCF) approach, which assumes no change from the previous assessment.A further sensitivity analysis will be conducted to assess the impact of participants who have not reached near FH by the end of the study. For the primary analysis, all participants will be included and for any participants who have not reached near FH, their height recorded at the end of study follow-up visit will be used. Although we anticipate this to be a rare event, we will conduct a sensitivity analysis (for the primary outcome only) which excludes any participants who have not reached near FH by the end of the study. Full details are included in the SAP.