Thirty-year trends in sudden deafness from four nationwide epidemiological surveys in Japan

CONCLUSIONS: The estimated annual number of patients with sudden deafness treated in Japan has increased during the last 30 years, especially in the elderly population. Hypertension and diabetes mellitus could contribute to the etiology of this disorder. OBJECTIVES: To investigate the epidemiological trends of sudden deafness in Japan over the past 30 years by analyzing data from national surveys. MATERIALS AND METHODS: Nationwide epidemiological surveys on sudden deafness were conducted four times by the Research Committee of the Ministry of Health and Welfare in Japan. The first, second, third, and fourth surveys were performed in 1972, 1987, 1993, and 2001, respectively. RESULTS: The estimated annual numbers of patients with sudden deafness treated in Japan were 4000 in 1972; 16,700 in 1987; 24,000 in 1993, and 35,000 in 2001. The average ages of patients at onset were 39.1, 45.4, 49.3, and 51.3 years, respectively. Thus, both the number of patients and the average age of patients with sudden deafness have increased during the past 30 years. Patients with sudden deafness in the fourth survey exhibited hypertension and diabetes mellitus more frequently than did patients in the first survey; this trend was particularly noticeable among elderly patients.