Background Low back pain (LBP) is a leading cause of disability and incapacity for work. It often occurs in combination with pain at other anatomical sites. We hypothesised that a general propensity to musculoskeletal pain might account for variation in the prevalence of LBP across occupational groups in different countries.

Methods To explore this hypothesis, we used data from the CUPID study on 9,055 participants in 45 occupational groups from 18 countries. Pain propensity score was defined as the number of painful anatomical sites outside the low back at baseline. We explored the association of personal and group-level risk factors assessed at baseline with disabling LBP in the month before follow-up some 14 months later. Associations were summarised by prevalence rate ratios (PRRs) and 95% confidence intervals (CIs) derived from random-intercept Poisson regression models with robust standard errors.

Results Overall prevalence of disabling LBP in the 45 occupational groups varied from 6% among sales workers in Japan to 46% among nurses in Nicaragua, and correlated strongly with the mean pain propensity score for the occupational group (Spearman rho = 0.58). An analysis that included all significant risk factors showed strong associations with female sex, older age, and psychological variables. However, after allowance for these covariates, the association with pain propensity score was notably stronger (PRR (95% CI) for 6+ v 0 sites with pain: 2.6 (2.3, 3.1)). The population attributable fraction for pain propensity score (1+ v 0) was 40.3%, and was much higher than for other risk factors.

Conclusions Large international variation in the prevalence of disabling LBP is driven largely by differences in general propensity to musculoskeletal pain rather than by factors specific to the low back. Future interventions should aim at reducing general propensity to musculoskeletal pain.