Frequency of multiple sclerosis in Menorca, Balearic Islands, Spain

Objective: To establish prevalence and incidence of multiple sclerosis (MS) in Menorca (Balearic Islands, Spain; population: 67,009). Methods: An exte nsive epidemiological study was undertaken using all available information sources. Patients were classified according to Poser's criteria. Results: T he prevalence rate of definite and probable MS was 68.6/100,000 (95% confid ence interval 50.3-91.6). The incidence rate was 3.4/100,000/year (95% CI 2 .2-5.3). The time lag between the first symptom and diagnosis was 10.2 year s for patients with disease onset before 1987 and 2.1 years for patients wi th onset be tween 1987 and 1996. Conclusion: Menorca's population has a mod erately high MS risk, with a prevalence rate the highest reported for a Spa nish region. Copyright (C) 2001 S. Karger AG, Basel.