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Serum cotinine level and incident hearing loss: a case-control study.

BACKGROUND
A growing body of literature suggests an association between cigarette smoking and hearing loss.


OBJECTIVE
To assess the relation between levels of serum cotinine, a biomarker of exposure to tobacco smoke, and incident hearing loss.


DESIGN
A cross-sectional, incident, case-control study of participants selected from a population-based cohort.


SETTING
Testing was conducted at the Beaver Dam Community Hospital, Beaver Dam, Wis.


PARTICIPANTS
A total of 197 participants with incident hearing loss and 394 control participants, aged 53 to 75 years, selected from the 2800 participants of the 5-year follow-up examination of the population-based Epidemiology of Hearing Loss Study, 1998-2000.


MAIN OUTCOME MEASURE
Incident hearing loss. The incidence of hearing loss was defined as a pure-tone average of thresholds at 500, 1000, 2000, and 4000 Hz greater than 25-dB hearing level in either ear at follow-up among those without hearing loss at baseline.


RESULTS
No significant associations were found between serum cotinine levels and incident hearing loss.


CONCLUSIONS
These results were not consistent with a previous report, which found cross-sectional associations between prevalent hearing loss and current smoking and environmental tobacco smoke exposure in the home. Longer-term longitudinal studies of smoking and/or serum cotinine levels and the subsequent development of hearing loss may help clarify these associations.