Development and application of an index of social function.

Brief indexes of social function were constructed in a project to develop a health index questionnaire designed to measure the social, emotional, and physical function of free-living populations. The social function items have been found to be generally applicable, capable of application by lay interviewers, and acceptable to interviewees. Initial evaluations to form composite scores for social function items have demonstrated their validity against concurrent assessments of a health professional. These social function indexes have been successfully applied in two randomized trials of innovative primary care services. The criteria for inclusion of items in the social function index questionnaire, the generation of the instrument, and the evaluation of questionnaire responses for their validity are summarized here.