Identification of Responders to Amiodarone: Subgroup Analysis of the EMIAT Study

Clinical trials often judge the efficacy of a new treatment by
comparing the survival patterns of patients who are randomly
assigned to undergo the new or a standard/placebo treatment.
Usually, the entire groups are analyzed, although certain subgroups
of patients may react differently to the new treatment than others.
Some patients taking the new treatment might benefit from it (the
positive responders) while others may be harmed by it (the negative
responders). We applied a newly developed responder identification
method (Kehl&Ulm, 2003) on the doubleblinded placebo controlled
European Myocardial Infarction Amiodarone Trial (EMIAT). The
method, which is based on bump hunting, proceeds to find the so
called predictive factors, which describe positive and negative
trends in survival in special subgroups of patients, solely due to
Amiodarone. Factors found to be predictive were: age, previous
infarction, beta-blocker treatment, onset, NYHA classification, and
sex. Negative responders to Amiodarone, i.e. patients taking
Amiodarone who survived shorter than a similar group under placebo,
were patients who were older than 65 years, have had a previous
infarction, and were not on beta-blockers. Positive responders to
Amiodarone, (longer survival time), were male patients who were not
negative responders, had NYHA classification greater than or equal
to two, and onset greater than one. Further studies are needed to
investigate this hypothesis.