Advances in the measurement of functional status: construction of aggregate indexes.

This article summarizes tests of the appropriateness of aggregating specific categories of physical capacities and limitations into aggregate functional status indexes. Self-administered questionnaires were used to gather data from 4,603 people between 14 and 66 years of age. Cumulative indexes defining ranked levels of functional status were derived for two global constructs of functioning (personal and role functioning). Each index is scored to define chronic limitations and those of shorter duration. Personal functioning includes self-care, mobility and physical activity categories. Role functioning includes role and general activity categories. An index that aggregated personal and role limitations did not satisfy the assumptions of cumulative scaling.