, considering both failures at the end of treatment and
recurrence of TB over 24 months as the primary endpoints, with
a type I error of 0.05, and a type II error of 0.20, the definition of
equivalence as 5% (0.05), the approximate sample size for each
regimen was calculated to be 323. Allowing for 10% attrition in
patients over a 24-month follow-up period and expected
proportion of patients with drug resistant TB at intake to be
10%, the final sample size was calculated to be 400 patients for
each regimen.