Varicose veins in the lower extremities in relation to occupational mechanical exposures: a longitudinal study

Objectives To evaluate if occupational mechanical exposures are associated with an increased risk of surgery for varicose veins (VV) in the lower extremities. Methods We conducted a longitudinal study of persons from the Musculoskeletal Research Database at the Danish Ramazzini Centre who were 18-65 years old when they provided baseline questionnaire data during 1993-2004. Exposure estimates were obtained from a job exposure matrix based on expert ratings. The register information on first-time surgery for VV was retrieved. We used Cox regression analyses. Results During 416 317 person-years of follow-up among 38 036 persons, 851 first-time operations for VV occurred. Using standing/walking <4 h/day and uncommon lifting as references, exposure-response relationships with risk of surgery were found for men. For women, the risk increased too, but without clear exposure-response patterns. The adjusted HRs for >= 6 h/day spent standing/walking were 3.17 (95% CI 2.06 to 4.89) and 2.34 (95% CI 1.72 to 3.19) for men and women, respectively. For high lifting exposures (>= 1000 kg/day), the adjusted HRs were 3.95 (95% CI 2.32 to 6.73) for men and 2.54 (95% CI 1.95 to 3.31) for women. Other risk factors were increasing age for men and parity for women. Minimal leisure-time physical activity, a high body mass index and smoking were not associated with increased risk. Conclusions The results suggested an increased risk of surgery for VV in relation to prolonged standing/walking and heavy lifting and a preventive potential of more than 60% of all cases in exposed occupations.