Descriptive epidemiology of chronic fatigue syndrome based on a nationwide survey in Japan

In order to clarify the epidemiological features of chronic fatigue syndrome (CFS), a nationwide survey was conducted using the Japanese version of the CDC Criteria prepared by the CFS Research Group of Japan. All clinical departments of internal medicine, pediatrics, psychiatry and neurology at university hospitals and at ordinary hospitals with 200 or more beds were surveyed. Major results were as follows: (1) Period prevalence adjusted for response rate was 0.85 (0.63 for males and 1.02 for females) per 100,000 population during the year 1992; (2) Based on the first and final dates of hospital visits, the prevalences on January 1 of 1992 and 1993 were 0.40 and 0.60 per 100,000 population, respectively, suggesting an increasing trend; (3) Reported new cases during 1992 were 301, and the response adjusted-incidence was estimated to be 0.46 per 100,000 person-years; (4) The proportion of post-infectious CFS cases was 14.8% for both sexes, and tended to be slightly higher among females than males, but was not related to age. Three clusterings of two cases were reported.