A comparison of statistical outcome variables in extremely low birth weight infants.

Three different summary statistics of developmental outcome are described. These include the "handicap ratio" (handicapped individuals divided by survivors), the "handicap rate" (handicapped individuals divided by live births for that birth weight group), and the "handicaps per 10,000 live births" (handicapped individuals divided by 10,000 live births for a geographic region). An analysis of these statistics was undertaken using a sample of extremely low birth weight (ELBW) (less than 1,001 g) infants born in Hawaii during the period of 1975-1981. The results of this study showed a poor correlation between these summary statistics. The results suggest that these statistics represent different aspects of outcome in the ELBW infant. Suitable uses for each of these variables is discussed.