Measuring Disability Prevalence

This paper reviews what is meant by disability and puts forth a way of measuring disability suitable for internationally comparable prevalence rates. The basic trend in this regard is to measure functional limitations, rather than disability, and then use different severity thresholds for defining disability based on the purpose of measurement. After explaining this approach, the paper then goes on to summarize recent studies that use this methodology. Overall, as generally defined, disabled people represent a significant proportion of the world's population. Data from developed countries and some recent studies in developing countries over several regions (namely, Brazil, Ecuador, India, Nicaragua, Vietnam, and Zambia) suggest that an estimate of 10-12 percent is not unreasonable. This estimate is in line with the United Nations' often cited figure of 10 percent, which in fact was an informed guess based on data available from developed countries. This paper will argue, however, that a single disability prevalence rate can be highly problematic. Better practice would be to report at least two prevalence rates, one representing a moderate threshold for functional limitations and one with a more severe threshold.