all adverse events were monitored and recorded.
Unblinded data were made available to an independent
data and safety monitoring board.
Statistical Analysis
We assumed a rate of incessant or recurrent pericarditis
of 30% in the placebo group at 18
months5,16 and estimated that colchicine could reduce
the proportion of patients with incessant or
recurrent pericarditis by half. With a two-sided
alpha level of 0.05, a total enrollment of 240 patients
was needed to attain a power of 80% to detect
an absolute reduction of 15 percentage points
in the proportion of patients with incessant or recurrent
pericarditis in the colchicine group.
All analyses were performed on the basis of the
intention-to-treat principle. Data were expressed
as means and standard deviations. We used the
Mann–Whitney test for continuous variables and
the chi-square test for categorical variables. A
two-sided P value of less than 0.05 was considered
to indicate statistical significance. We used
the Kaplan–Meier method to estimate time-toevent
distributions, which were compared with
the use of the log-rank test. Analyses were performed
with SPSS software, version 13.0.
R esult s
Patients
Enrollment started in August 2005 and ended in
December 2010. Follow-up continued through
June 2012, with a predetermined stopping point
providing a minimum of 18 months of follow-up
for the primary outcome.
Study enrollment, randomization, and retention
are shown in Figure 1. Of the 280 patients
who were screened, 240 (85.7%) were enrolled;
120 patients were randomly assigned to each of
the two study groups. The baseline demographic
and clinical characteristics of the patients were
similar in the two groups (Table 1). The mean
age of the patients was 52.1±16.9 years, and 60%
were male. Clinical signs and symptoms were
consistent with previous findings from published
unselected series of patients with acute pericarditis.7-9
There was more than 95% adherence to the
study-drug regimen before the primary outcome
was reached or the study was completed, and
adherence rates did not differ significantly between
the two study groups. All patients who
tolerated treatment with colchicine or placebo
discontinued therapy at 3 months, as planned.
No open-label colchicine was administered after
the end of the study period. No patient was lost
to follow-up, and all patients were analyzed for
outcomes according to the original study-group
assignments. Patients were followed for an average
of 22 months.
Outcomes
The main outcome results are reported in Table 2.
The primary outcome of incessant or recurrent
pericarditis occurred in 20 patients (16.7%) in
the colchicine group and in 45 patients (37.5%) in
the placebo group (relative risk reduction in the
colchicine group, 0.56; 95% confidence interval