RISK-FACTORS FOR MULTIPLE-SCLEROSIS - A CASE-CONTROL STUDY IN ISRAEL

This case-control study was aimed at identifying environmental risk fa ctors for multiple sclerosis (MS). Ninety-three Israeli-born MS patien ts identified in country-wide studies and 94 age- and sex-matched cont rols were interviewed. The questionnaire covered a large span of facto rs at ages 0, 10 and onset of the disease, with particular emphasis on socioeconomic status (SES) and sanitary conditions (SAN). A significa ntly larger percentage of patients reported frequent respiratory disea ses. Patients and their parents had significantly (p < 0.01) higher ed ucational levels than controls. The SES and SAN at age 10 were also sy stematically higher among patients, but significance was reached only when the frequencies of conditions indicating extremely low values of SES or SAN were compared. It is possible that the protective effect of low SES and SAN on risk of MS can be detected only when living condit ions are well below average, as is frequent in developing countries.