Prevalence of musculoskeletal symptoms by employment characteristics among agricultural industry workers: Analysis of the National Health Interview Survey, 2004–2008

Background: The agricultural industry includes a substantial number of small-size operations, and commonly uses non-regular employees, such as family labor. The risk of musculoskeletal symptoms by employment characteristics among these workers is not well understood. Methods: Prevalence of musculoskeletal symptoms (low back, neck, shoulder, elbow, wrist/hands, or lower extremities) was estimated using National Health Interview Survey data from 2004–2008. Agricultural workers were defined as persons who currently worked in crop or animal production, or support activities for agriculture. The weighted prevalence of musculoskeletal symptoms was examined by number of employees (<10, 10–99, ≥100 employees), and between paid and non-paid workers using generalized linear models with Poisson distribution assumption. Prevalence ratios (PRs) and 95% confidence intervals (CI) were obtained. Results: Sixty-seven percent of agricultural workers were employed in small operations (<10 employees), and 17% were non-paid. Prevalence of musculoskeletal symptoms among all agricultural workers was 41% (27% for low back or neck, 17% for upper extremities, and 19% for lower extremities). Prevalence of musculoskeletal symptoms was lower among workers in medium-sized operations, 27%, than in small operations, 47% (PR=1.71, 95% CI 1.32–2.23), or in large operations, 41% (PR=1.49, 95% CI 0.96–2.32); and higher among non-paid workers, 50%, than paid workers, 39% (PR=1.29, 95% CI 1.02–1.62). However, differences were not significant after adjustment for age, sex, and race/ethnicity. Conclusions: Musculoskeletal symptoms were not independently associated with number of workers employed, or type of employment (paid or non-paid) in a nationally representative sample of agricultural workers.