The cross-sectional population sample studied here was randomly selected from the population register of northern Finland. The subjects comprised 10 different age groups between 2 and 75 years of age. Pure tone averages over the frequencies of both 0.5, 1 and 2 kHz and 0.5, 1, 2 and 4 kHz - i.e. better ear hearing levels (BEHL) of BEHL0.5-2kH and BEHL0.5-4kHz - were calculated. The prevalence of various grades of hearing impairment was investigated among the 3518 people who participated in audiometric measurements. Two different classifications were used to grade the hearing impairment. According to the World Health Organization (WHO) classification (1991), 94.3% of the subjects had normal hearing, whereas 3.8% had mild hearing impairment, 1.3% had moderate impairment, 0.4% severe impairment and 0.1% profound impairment. When the more recent EU definition (1996) was used, 85.3% of the subjects had normal hearing. Mild impairment was found in 11.5% of the subjects, moderate impairment in 2.8%, severe impairment in 0.3%, and profound in 0.1%. The difference between the two definitions mentioned above (resulting in different prevalence figures of hearing impairments) is clear. The WHO classification reveals the need for rehabilitation and can thus be used as a basis of resource allocation, whereas the EU proposal reveals even the mildest hearing impairments and hence better illustrates the real prevalence of impairment. The need for the current and future audiological services may be estimated from the prevalence rates of hearing impairments. The proportion of the Finnish elderly - the people most frequently using health services - is expected to increase from today's 15% to 23% within the next 20 years. The same phenomenon is to be expected in other Western societies.
The possible effect of handedness on hearing threshold asymmetry was analysed in a large random population representing a normal population. The left ear was on an average slightly but significantly poorer than the right ear at high frequencies, especially at 4 kHz, while at low frequencies the right ear was on average poorer than the left ear. A matched control group of the right-handed subjects was formed for 211 left-handed subjects. Among the left-handed subjects the average ear asymmetry resembled the ear asymmetry of the whole population, the right-handed subpopulation, and of the matched control group. In conclusion, it seems that handedness cannot be responsible for the average inferiority of hearing in the left ear at 4-kHz or for the average slight superiority of the left ear at 0.125-0.5 kHz. However, this analysis does not rule out possible minor effects of handedness on ear asymmetry.
Interaural asymmetry of hearing thresholds at 4 kHz was analysed in four populations exposed to occupational noise. The left ear was found to be on average significantly worse than the right ear, among both the male and female subjects. In the male population the left ear was twice as often the worse ear as the right one. In the female population the corresponding ratio was 1.5. The average inferiority of the left ear increased as a function of the hearing threshold level. Among subjects with abundant shooting (reindeer herders) the average inferiority of the left ear was close to the average of all male subjects. Interaural difference increased as a function of the hearing threshold level, both among subjects with the left ear and subjects with the right ear being the worse one. In the male population the interaural difference was significantly greater in the former than in the latter group of subjects.
The choice of antimicrobials did not influence the duration of middle ear effusion, which was much shorter than had been thought previously. Children with unilateral AOM were cured much more quickly than those with bilateral AOM.
Calculations of the needs of healthcare, hearing healthcare included, are usually based on clinical data rather than on valid prevalence figures. According to our recent population study, the number of citizens needing hearing aids in Finland will be twice the figure usually presented, 280 000 for the country as a whole (population 5.1 million). The penetration of hearing aids was only 41%. Taking this and the ageing of the population into account, the economic challenges of hearing healthcare will be alarming in the new millennium.
Background: Disappearance of middle ear effusion is one of the most important outcomes in the treatment of acute otitis media (AOM). Aim: To evaluate the duration of effusion in AOM treated by antimicrobials and to find factors influencing it. Methods: Parents of 90 children with AOM monitored daily the disappearance of effusion with tympanometry. The children were randomly allocated to be treated with either oral amoxicillin or cefuroxime‐axetil for 10 d. Daily monitoring lasted for 14 d or until the tympanogram was normal (curve A or C) in both ears. Pneumatic otoscopy was carried out every 2 wk. Results: Normal tympanograms were obtained after a median time of 7.5 d (range 1–58 d) among 75 successfully monitored patients. In two‐thirds (69%) of them, effusion resolved in 14 d. The median duration of effusion did not differ significantly between the two treatment groups (8 vs 7 days, p=0.7). The children who had unilateral AOM cured more rapidly than those with bilateral AOM (5 vs 19 d, p<0.001). In logistic regression analysis adjusted for age, bilaterality explained treatment failure at 2 wk with an odds ratio of 28.1 (95% CI 4.6–169.5, p<0.001).
Conclusion: The choice of antimicrobials did not influence the duration of middle ear effusion, which was much shorter than had been thought previously. Children with unilateral AOM were cured much more quickly than those with bilateral AOM.
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