Comparison of mortality and rates of cerebral palsy in two populations of very low birthweight infants

Comparisons of mortality and rates of cerebral palsy in different populations can be confusing. This is illustrated by comparing two populations of very low birthweight infants both in the 1980s, one from the Netherlands, the other from the UK (Oxford region). Although a number of biases were controlled for wile comparing two large geographically defined populations, by assessing the survivors at similar ages and describing their health status in a standard way, some problems in interpretation of outcome remained