Methods for additional analyses (e.g. subgroup analyses) {20b}
Key additional analyses will include an assessment of interactions of interventions and possible variation of the intervention main effects by period and site-level baseline characteristics, including faint rates (tertiles); size as characterised by a number of donors bled (tertiles); and type of site (fixed or mobile). Analyses will follow the same approach as for the primary outcome with the addition of relevant interaction terms. Furthermore, individual-participant data will be secondarily analysed using a hierarchical generalised linear mixed model to assess possible interactions of interventions with selected participant characteristics (e.g. age, sex) accounting for the cluster randomised trial design at the site level.