PREVALENCE AND ETIOLOGY OF PROFOUND DEAFNESS IN THE GENERAL-POPULATION OF SICHUAN, CHINA

People with profound deafness were surveyed in the general population of Sichuan. The results showed that the overall prevalence in Sichuan was 0.186 per cent (236/126 876) of the general population, males 0.212 per cent (135/63 741), females 0.159 per cent (101/63 135) (p less-than-or-equal-to 0.05). Two hundred and fifteen (92 per cent) cases were older than 10 years. but 227 (96 per cent) lost their hearing under the age of 10 years, 192 (80 per cent) under five years. and 104 (44 per cent) were congenital. There was no significant difference in prevalence of deafness between the population located in urban and rural areas. However, the population living in the flat area and mountain area had a much higher prevalence than that of the hill people (p less-than-or-equal-to 0.05). Amongst the nationalities investigated, there existed significant differences in prevalence. Both the population of the Hui and the Lisu presented a significantly higher prevalence of profound deafness than that of the others. In aetiology, genetic factors may account for 43 per cent (101/236) of the cases, amongst which, autosomal recessive (AR) deafness is 92 per cent (95/104) and autosomal dominant (AD) 5.4 per cent. Environmental factors were thought to be responsible for 35.6 per cent (84/236) of cases, including infectious diseases (31 per cent), ototoxic antibiotics (2.6 per cent), injury (1.7 per cent), and asphyxia (0.4 per cent). The number of cases of unknown origin were 20.3 per cent. It is suggested that, in China, the importance of genetic factors in hearing impairment should be emphasized. In addition, infectious diseases and ototoxicity play an important role in causing deafness.