Cohort study of occupational risk factors of low back pain in construction workers.

OBJECTIVES: To identify work related risk factors of future low back pain (LBP) in a cohort of construction workers free of LBP at the start of follow up. METHODS: The Hamburg construction worker study comprises 571 male construction workers who have undergone two comprehensive interview and physical examination surveys. A cohort of 285 subjects without LBP at baseline was identified. After a follow up of 3 years, the 1 year prevalence of self reported LBP was determined in the 230 men followed up (80.7%). Prevalence ratios (PRs) with 95% confidence intervals (95% CIs) of LBP at follow up according to self reported work tasks of construction workers measured at baseline were estimated from Cox's regression models which were adjusted for age, and anthropometric measures. RESULTS: At follow up 71 out of 230 workers (30.9%) reported LBP during the preceding 12 months. Four work tasks (scaffolding, erecting roof structures, sawing wood, laying large sandstones) with an increased risk of 1 year prevalence of LBP at follow up were further evaluated. After further adjustment for occupation the relative risk was increased for workers who had reported > or = 2 hour/shifts laying large sandstones (PR = 2.6; 95% CI 1.1 to 6.5). Work load of bricklayers was additionally estimated by an index on stone load (high exposure: PR = 4.0; 95% CI 0.8 to 19.8), and an index for laying huge bricks/blocks (yes/no: PR = 1.7; 95% CI 0.5 to 5.7). CONCLUSIONS: The results suggest that self reported differences in brick characteristics (size and type of stone) and temporal aspects of the work of bricklayers (average hours per shift laying specified stones) can predict the future prevalence of LBP. The data have to be interpreted with caution because multiple risk factors were tested.

Construction work and low back disorder. Preliminary findings of the Hamburg Construction Worker Study.

STUDY DESIGN: Cross-sectional part of a longitudinal study in 571 male construction workers. OBJECTIVES: The Hamburg construction worker study is being conducted to assess the extent of musculoskeletal disorders in construction workers and factors predisposing for or leading to musculoskeletal disorders. The purpose of this analysis is to report findings about the association between job history and low back disorder. SUMMARY OF BACKGROUND DATA: Repetitive strain in forced positions during long periods of time has been reported as a risk factor for low back disorder. Of all construction workers, bricklayers predominantly are exposed to these conditions. METHODS: Subjects were recruited mainly from a routine health check-up. A structured interview with complete job history, job related activities, and symptoms was administered, and a detailed standardized physical examination was performed. Age-adjusted prevalences of low back pain were calculated, and logistic regression models were used to estimate odds ratios and their confidence intervals for different durations of working in a specific job category and physical signs of low back disorder, adjusting for a variety of possible confounders. RESULTS: The 12 month prevalence of low back pain was highest in painters (57%), intermediate in concrete builders and bricklayers (41%), and lowest in carpenters and unskilled workers (38%). The age-adjusted odds ratio (95% confidence interval) of low back disorder for having worked longer than 10 years as a bricklayer was 2.3 (1.2-4.5). CONCLUSIONS: Working longer than 10 years as a bricklayer was associated with signs of low back disorder. No comparable associations were found for house painters, carpenters, nor concrete builders. If replicated, these findings could be used to focus preventive measures on bricklayers with a long job history.