Medical examination of Israeli 17-year-olds before military service as a national resource for health information.

At age 17 years Israelis undergo medical examination for the purpose of health classification for military service. The potential use of this extensive data collection system for epidemiologic studies is illustrated for selected conditions. Trends in diagnosed disorders over a 25-year period are exemplified in the changing prevalence of tuberculosis, bronchial asthma, diabetes, epilepsy and heart defects. Within birth cohorts, cross-sectional analyses of height, body mass, blood pressure and disorders--such as bronchial asthma, allergic rhinitis, diabetes, psychiatric diagnoses and such genetic conditions as familial Mediterranean fever--point to clear ethnic differences. Educational level is strongly associated with measures of health status. Potential uses of this resource include: detecting groups in need of preventive, curative and rehabilitative care, assessing changing needs and priorities of health care, evaluation of intervention programs and health services provided in childhood, a wide spectrum of etiologic studies including assessment of health effects of social change, follow-up studies including the natural history of disorders, and developing data systems such as national registries of rare or important conditions. Issues relating to data reliability and validity, changing disease classification and nonexamination of groups exempted from military service limit interpretation of findings and restrict uses of this resource. Emphasis on standardization of data collection and diagnostic criteria, quality assurance and improved data management will be necessary.