Methods to adjust for multiple comparisons in the analysis and sample size calculation of randomised controlled trials with multiple primary outcomes

Table 4 Sample size per group, assuming three outcomes, 90% disjunctive power, after applying a Bonferroni correction

Standardised effect sizes for each of the 3 outcomes			Sample size required to obtain 90% DISJUNCTIVE power				Sample size required to obtain 90% MARGINAL power for each outcome
Standardised effect sizes for each of the 3 outcomes			Correlation between outcomes
Out.^a 1	Out. 2	Out. 3	0.2	0.4	0.6	0.8	Out. 1	Out. 2	Out. 3
0.2	0.2	0.2	353	401	456	524	677	677	677
0.2	0.3	0.3	185	207	229	254	677	302	302
0.2	0.4	0.4	109	120	131	143	677	171	171
0.2	0.5	0.5	71	77	84	92	677	110	110
0.3	0.3	0.3	157	179	203	234	302	302	302
0.3	0.4	0.4	101	114	127	143	302	171	171
0.3	0.5	0.5	68	76	83	92	302	110	110
0.4	0.4	0.4	89	101	114	132	171	171	171
0.4	0.5	0.5	64	72	81	91	171	110	110
0.5	0.5	0.5	57	65	73	84	110	110	110

Sample sizes provided are required per arm. A Bonferroni correction is applied for all calculations to account for the multiple comparisons. Key: ^a‘Out’ Outcome

ISSN: 1471-2288