7. Sample size The PCR corrected day 42 ACPR of AL was 97% in 2008 ( = before the national recommendation was changed in favour of A). It is likely that DP should be as efficacious as AL and it is therefore appropriate to conduct a non-inferiority trial13. Assuming 97% ACPR for both treatments, 5% significance level (alpha), 80% power (1-beta) and a non-inferiority limit (d) of 5% 144 children are required in each arm. Assuming a 20% loss to follow up a total of 346 children should be included.