The primary study outcome was clinical cure at
the test-of-cure visit. Two primary efficacy analyses
were performed: one in the intention-totreat
population and the other in the population
of patients who could be evaluated (Fig. 1). A
lack of clinical cure was defined as a lack of
resolution of signs or symptoms of infection, the
occurrence of side effects that necessitated discontinuation
of treatment with the study medication
within the first 48 hours, or any one of
the following before the test-of-cure visit: occurrence
of a skin infection at a new body site,
unplanned surgical treatment of the skin infection,
or hospitalization related to the infection.
The primary null hypothesis was that clindamycin
and TMP-SMX would have equal rates of cure.
The study was designed as a superiority trial with
80% power to detect an absolute difference between
the two treatment groups of 10 percentage
points in cure rates (85% vs. 95%) in the
population that could be evaluated, at an alpha
level of 0.05. Assuming a 20% attrition rate, we
calculated that 524 patients (262 in each group)
needed to be enrolled. The prespecified secondary
outcomes were cure rates at the end of treatment
and at the 1-month follow up visit; cure
rates in the adult and pediatric populations; cure
rates among patients with cellulitis, abscess, or
mixed abscess and cellulitis (defined as separate
lesions of abscess and cellulitis) at the test-ofcure
visit; and adverse-event rates. Comparisons
between groups were performed with the use of
Pearson’s chi-square test, Fisher’s exact test, or
an analysis-of-variance test, as appropriate; all tests
were two-sided. Interim analyses for safety were
performed by an independent data and safety
monitoring committee. Findings from the trial
are described in accordance with Consolidated
Standards of Reporting Trials (CONSORT) guidelines.
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