Multiplicative effect of smoking and age on hearing impairment.
OBJECTIVE
To determine the combined effect of smoking and age on hearing impairment.


METHODS
Pure tone audiometry test was conducted on 263 residents of a rural village who were not exposed to noise. The pack-years of smoking were computed from the subjects' smoking history. The association between pack-years and hearing impairment was assessed. The combined effect of smoking and age on hearing impairment was determined based on prevalence rate ratio.


RESULTS
There was a statistically significant trend in the number of pack-years of smoking and age as risk factors for hearing impairment. The prevalence rates of hearing impairment for nonsmokers aged 40 years and younger, smokers aged 40 years and younger, nonsmokers older than 40 years of age, and smokers older than 40 years of age were 6.9%, 11.9%, 29.7%, and 51.3%, respectively. The prevalence rate ratio for nonsmokers aged 40 years and younger, smokers aged 40 years and younger, nonsmokers older than 40 years of age, and smokers older than 40 years of age (nonsmokers aged 40 years and younger as a reference group) was 1, 1.7, 4.3, and 7.5, respectively. The prevalence rate ratios showed a multiplicative effect of smoking and age on hearing impairment.


CONCLUSIONS
Age and smoking are risk factors for hearing impairment. It is clear that smoking and age have multiplicative adverse effects on hearing impairment.
Noorhassim
I
I
Department of Community Health, Faculty of Medicine, National University of Malaysia, Kuala Lumpur.
Rampal
K G
KG
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001301:Audiometry, Pure-Tone; D006311:Hearing Disorders / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D016014:Linear Models; D008296:Malaysia / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012424:Rural Population; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology