A global disability indicator

Disability is difficulty performing roles and activities due to health problems. It is largely experienced by older persons as they accumulate progressive chronic conditions. To measure functional status of individuals and populations, contemporary surveys include sets of detailed items about disability. Little effort has gone into developing global indicators of disability that cover the concept briefly but well. A global disability indicator is a compact and inexpensive device for public health surveillance and scientific study of disablement. I present and critique items that have been used in North American surveys. Good candidates are selected for methodological study. Both laboratory-based cognitive studies and large-scale statistical studies are recommended; the first will reveal meanings of items and responses and the second, items' systematic structure and prediction ability. The ultimate goal is to identify one or a few fine indicators for widespread inclusion in population health surveys.