Study Objectives
The primary objective in each study component is to
test whether the use of candesartan, compared with placebo,
will reduce the combined endpoint of cardiovascular
death or hospitalization for the management of
congestive heart failure. In pooled analyses of the 3
studies, the effect on all-cause mortality will be assessed.
The secondary and other objectives are described in
Table 2.
Statistical Methods
To meet the primary objective in each study and to
assess the effect on all-cause mortality, the primary endpoint
of time from randomization to the first occurrence
of a cardiovascular death or hospitalization for the management
of CHF will be analyzed by a 2-sided log-rank
test. For patients with multiple occurrences of events, the
time to the first occurrence will be used. The null hypothesis
will be no difference between incidence curves.
To meet the secondary objective in each study the
same test procedure will be used. If, and only if, there is
a significant difference in the combined endpoint of
cardiovascular (CV) mortality or CHF hospitalization, a
significant difference in the combined endpoint of CV
mortality or CHF hospitalization or myocardial infarction
will also be considered without statistical penalty
because this will be a closed test procedure.
Estimated endpoint rates have been calculated from
the Studies of Left Ventricular Dysfunction (SOLVD)
and the Digitalis Investigators Group (DIG) studies. To
maintain power, the recruitment or the follow-up period
may be changed.
The power calculation is based on a 2-sided log-rank
test for comparing the incidence curves of placebo and
candesartan at a significance level of .05. Table 3 gives
the calculated power with the log-rank test to detect a
16% to 20% decrease in the annual placebo incidence
with 18 months recruitment time and 42 months total
study time. The patients are equally distributed between
placebo and candesartan.