surveys in Baltimore, Maryland, and Hunterdon County, New Jersey. One of the objectives was to obtain estimates for the "prevalence of illness and disability resulting from chronic disease by diagnosis, degree and duration of disability." Three kinds of measures of the disabling effects of chronic conditions were used in the evaluation: (1) limitations on the ability to perform 11 selected activities of daily living; (2) limitations on overall functional capacity; and (3) limitations on the ability to work, keep house, or attend school (i.e., the person's usual major activity). The second measure remains one of the best scales for independent living. The third measure of limitations in roles, referred to here as activities, is an approach that has been used for decades in the National Health Interview Survey (National Center for Health Statistics, 1987a).

Interest in functional assessments during the 1940s and 1950s spurred the development of measures of functional deficits—what Deaver and Brown (1945) called "activities of daily living" (ADL). A variety of instruments were constructed including differing combinations of items (for an informative review, see Gresham and Labi, 1984). A review of ADL scales led Hoberman and Associates to conclude in 1952 that "daily activity measurement will have passed adolescence only when functional tests are properly graded, scored, validated, and normed, and their all-round practicability and utility demonstrated." More than 30 years later, Frey (1984) declared, "it is safe to say that, with the exception of only a very few ADL scales, development in this area remains preadolescent." In addition to the work of the Commission on Chronic Illness noted above, other notable efforts in the area include those of Lawton (1972), Lambert and colleagues (1975), and Katz and co-workers (1963, 1983).

The decade of the 1950s was marked by mounting concerns over criteria and decisions regarding compensation and other disability benefits, which led to other conceptual attempts—for example, by the American Medical Association (AMA) Committee on Medical Rating of Mental and Physical Impairment (1958). The committee's work was in response to the needs of workers' compensation programs—which had been plagued by litigations— to develop standardized ratings legitimized by the professional and scientific standing of the AMA. The committee distinguished between impairment and disability by pointing out that "permanent impairment is a contributing factor to, but not necessarily an indication of, the extent of a patient's permanent disability." To the committee, "[c]ompetent evaluation of permanent impairment requires adequate and complete medical examination, accurate objective measurement of function and avoidance of subjective impressions and non-medical factors such as the patient's age, sex, or employability." Because the committee's domain was defined as that of impairment, disability was left without further clarification. What is important, however, is the reference to the functional dimension. Such a reference was also included in a report by the Criteria Committee of the New York Heart Association

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