Epidemiology of hearing disorders. Some factors affecting hearing. The Copenhagen Male Study

This epidemiological investigation reports on the results from a 10-year follow-up examination concerning hearing and factors known to cause hearing problems. In addition, an evaluation concerning the possible association between hearing impairment and factors affecting the state of health is reported. The original sample comprised 5,050 subjects, and at the present examination 3,387 (67%) males at a median age of 63 years (range 53-75) participated. An increasing prevalence of 30-40% of hearing problems was demonstrated with increasing age. A prevalence of 17% of tinnitus of more than 5 min duration was found; 3% indicated that their tinnitus was so annoying that it interfered with sleep, reading and/or concentration. The prevalence of tinnitus increased up to the age of 70, and seemed to remain constant thereafter. A significant correlation between experienced hearing problems and environmental factors causing damage to the hearing organ was found. Furthermore, a correlation between hearing problems and C3-S complement was found, but no correlations could be established between hearing problems and other blood groups. No correlation was found between cardiovascular disease and hearing problems except for minor circulatory problems, nor between hearing problems and hormonal diseases. It is concluded that the present study supports previous epidemiological investigations concerning the prevalence of hearing problems and factors affecting hearing. The association between hearing problems and C3-S complement, which to the authors' knowledge has not previously been reported, should be further evaluated. No association was found between hearing problems and other blood groups.