Need for Large Sample Sizes in Randomized Trials

Abstract

Prevention is an area of relevance and concern to all health professionals, in particular, pediatricians. This concept encompasses primary prevention of disease (such as diphtheria, pertussis, tetanus, and poliomyelitis) among healthy individuals as well as secondary prevention or the reduction in risks of complications, recurrences, or mortality among those already affected. It is unlikely that a new measure will have as dramatic an effect as did the poliomyelitis vaccine, a prevention measure, which reduced the incidence of paralytic disease in the vaccinated group more than 50% compared with children given placebo. Analogously, virtually none of the new therapeutic measures of promise is likely to have as clear-cut an effect as did penicillin, which decreased mortality from pneumococcal pneumonia approximately sixfold (from about 95% to 15%).