Cornell Medical Index as a health measure in epidemiological studies. A test of the validity of a health questionnaire.

The Cornell Medical Index (CMI) is a well-known health questionnaire, of established value as an aid to clinical diagnosis and as a screening procedure (Brodman, Erdmann, and Wolff, 1956). A recent review of the use of the CMI as an epidemiological tool cites numerous studies which support its value for this purpose, particularly as an indicator of emotional ill-health (Abramson, in press). The questionnaire has been shown to have a fair validity as a measure of the presence and degree of emotional disorder; this has been the common finding of a number of investigators in Britain and the United States, despite the lack of unison on definitions or criteria of mental health and illness. The CMI is possibly also of use as an index of general health; it appears, however, to have less value as an indicator of general somatic health or of the presence of specific disorders. The use of the CMI in comparative studies presents problems. There is evidence that the questionnaire is of little value in comparisons of widely divergent cultures, and there are indications that problems of comparative validity may also arise when it is used in comparing groups within a single general culture. A study of apparently healthy US army inductees of differing ethnic origins, for example, revealed corresponding differences in their CMI responses (Croog, 1961). This study was undertaken during 1962-4 among 120 randomly selected residents of a Jerusalem housing project. Its purpose was to test the validity of the CMI when applied in this community. The responses to the questionnaire were considered in relation to health appraisals made for this purpose by two physicians who were well acquainted with the subjects. Attention was directed to the influence on the validity of the questionnaire of a number of variables commonly utilized in epidemiological studies-age, sex, ethnic group (region of birth), educational level, and social class.