Respiratory symptom reporting error in occupational surveillance of older farmers.

Objective: Agricultural health studies often use respiratory symptom report as a surrogate measure of disease and exposure; little data exists on the accuracy of symptom report in a work-motivated population.

Methods: Screening spirometry and telephone survey data for Kentucky male farmers >55 year (n = 134) in the NIOSH Farm Family Health and Hazard Surveillance Project were compared to investigate the accuracy of symptom report as a measure of respiratory disease risk in older farmers.

Results: The prevalence of reported obstructive respiratory symptoms was 0.24 (95% CI = 0.17 to 0.31); objective measures increased prevalence to 0.35 (95% CI = 0.27 to 0.43). Customary symptom questions did not reliably reflect objective indicators of respiratory impairment.

Conclusions: Older farmers may not accurately report respiratory symptoms. Whether by intention or misinterpretation of physical cues, self-reporting errors in this population may introduce misclassification bias.