Influence of participation on mortality in a randomized trial of vitamin A prophylaxis.

Mortality of Sumatran children living in villages randomized to participate in a vitamin A capsule (200,000 IU) distribution program who received the capsule (n = 9776) was compared with those who did not (n = 2447) and with children living in villages randomized to serve as control subjects (n = 12,173). During the 4 mo after completion of the first distribution, mortality among preschool capsule recipients was less than 4% that of nonrecipients (p less than 0.001). Mortality among preschool nonrecipients was three times that of controls (p less than 0.05), suggesting strong selection bias. The potential biologic impact on childhood mortality attributable to vitamin A supplementation is estimated to exceed the 34% previously derived from the more conservative intent-to-treat analysis. One capsule every 6 mo may provide adequate protection for the vast majority of children. The single major limitation to maximum impact appears to be inadequate program coverage.