() () Random Low risk ‘Stratified blocked randomization was used to balance by ethnicity and also to balance by enrollment (as a cautionary measure against a sequence potential temporal or seasonal bias). A randomization scheme was developed separately for each of the three groups (ie, the strata). generation Within each stratum, the treatments were assigned within blocks. Because there were three treatment groups, the block size had to be divisible by 3; the data team selected a block size of six, which was unknown to the investigators or the pharmacists. In this way, at the end of each block (ie, enrollment of six subjects), each group was balanced in the number randomly assigned to the 400-, 2000-, and 4000-IU treatment groups.’ Allocation Unclear risk Not described. concealment Blinding Low risk ‘Double blind’ Incomplete Low risk Explanation for loss to follow-up (30% from allocation to analysis) explained. Analysis was by intention to treat. outcome data Selective Low risk Prespecified outcomes reported. reporting Other limitations Low risk No significant difference in baseline characteristics between groups () Random Low risk Randomization lists were generated by computer prior to the start of the study. sequence generation Allocation Low risk Randomization assignment was blinded to all participants and to the investigators except for the study biostatistician. Dose groups were concealment identified for logistical purposes using 6 letters (3 per dose group) as an additional measure against inadvertent unblinding. Blinding Low risk ‘Double blinded’ Incomplete Low risk Explanation for loss to follow-up (38% from allocation to analysis) explained. Analysis was by intention to treat. outcome data Selective Low risk Prespecified outcomes reported. reporting Other limitations Low risk After controlling for race and study site, no characteristics differed significantly between groups.
() () Random sequence generation Low risk ‘Stratified blocked randomization was used to balance by ethnicity and also to balance by enrollment (as a cautionary measure against a potential temporal or seasonal bias). A randomization scheme was developed separately for each of the three groups (ie, the strata). Within each stratum, the treatments were assigned within blocks. Because there were three treatment groups, the block size had to be divisible by 3; the data team selected a block size of six, which was unknown to the investigators or the pharmacists. In this way, at the end of each block (ie, enrollment of six subjects), each group was balanced in the number randomly assigned to the 400-, 2000-, and 4000-IU treatment groups.’ Allocation concealment Unclear risk Not described. Blinding Low risk ‘Double blind’ Incomplete outcome data Low risk Explanation for loss to follow-up (30% from allocation to analysis) explained. Analysis was by intention to treat. Selective reporting Low risk Prespecified outcomes reported. Other limitations Low risk No significant difference in baseline characteristics between groups () Random sequence generation Low risk Randomization lists were generated by computer prior to the start of the study. Allocation concealment Low risk Randomization assignment was blinded to all participants and to the investigators except for the study biostatistician. Dose groups were identified for logistical purposes using 6 letters (3 per dose group) as an additional measure against inadvertent unblinding. Blinding Low risk ‘Double blinded’ Incomplete outcome data Low risk Explanation for loss to follow-up (38% from allocation to analysis) explained. Analysis was by intention to treat. Selective reporting Low risk Prespecified outcomes reported. Other limitations Low risk After controlling for race and study site, no characteristics differed significantly between groups.
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