Epidemiology of hearing loss

Abstract

Epidemiology no longer concerns itself only with infectious diseases. Now it deals with the commoner non-infectious diseases in a population. In epidemiology, we deal with populations and this is the centre of the problem. Data on more than 30 000 cases of hearing loss were statistically analysed for the period 1966-1971. The number of males was higher than that of females in spite of the fact that, in the population, there is an inverse ration. The ratio of males to females increased as a function of age. The most frequent diseases were presbyacusis noise-induced hearing loss, sensorineural hearing loss of unknown origin, the different forms of chronic otitis and the consequence of these (cicatrisation, adhesive process, tympanosclerosis). The grades of hearing loss were determined in the different pathological processes and the distribution of these grades was calculated according to age. As regards sensorineural hearing loss, it was found that, among the patients older than 40 years, not only did the number of cases increase but the severity of the loss also. The number of hearing losses due to chronic otitis increased only up to the age group of 20-30 years. The number of cicatrisations, adhesions and tympanosclerosis increased among the older patients also. The grade of hearing loss caused by different conductive hearing increased with age. This was also observed in cases of tympanosclerosis in spite of the fact that these were clinically healed processes. The majority of the hearing levels in cases of sensorineural hearing loss remained stationary. Amongst the treated cases, improvement was noted in 8% Most cases of sudden hearing loss occurred amongst the older patients (47% improved; 11.7% deteriorated; 41.3% remained unchanged). Among the cases of sensorineural hearing loss caused by bacterial or viral agents, there was a greater chance for children and for the aged to sustain total deafness. © 1973 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.