To examine the association between self-reported physical workload and risk of herniated lumbar disc disease (HLDD) in a long-term follow-up of men without a history of back disorders at baseline.
Summary of Background Data.
Heavy physical workload is considered a risk factor for HLDD, but the issue is not definitively settled.
The Copenhagen Male Study is a prospective cohort study established in 1970 to 1971. At baseline, 5245 men answered a questionnaire about history of back disease and physical workload. Psychosocial working conditions, lifestyle, social class, and measured height and weight were included as potential confounders. Information about hospitalization due to HLDD was obtained from the National Hospital Register covering the period from 1977 to 2003. Hazard ratios were calculated by Cox proportional hazard regression model.
Among 3833 men without back disease history at baseline, the strongest predictor of hospitalization for HLDD was frequent strenuous physical activity at work; compared with unexposed, the hazard ratio with 95% confidence interval was 3.90 (1.82–8.38). Also, body height was a significant predictor, whereas body weight was only insignificantly associated with HLDD.
Among men without history of back disease reporting of frequent exposure to strenuous physical activity at work was a strong risk factor for later hospitalization due to HLDD.