Differences in the determinants of extensive as compared with more limited musculoskeletal pain

OBJECTIVES: To explore whether multi-site musculoskeletal pain differs from more localised musculoskeletal pain in its association with risk factors. METHODS: As part of the CUPID study, standardised questionnaires were used to ascertain exposure to risk factors and the prevalence of pain for a day or longer during the past month at each of 10 anatomical sites. Analysis was based on 12,410 participants from 47 occupational groups (mostly nurses and office workers) in 18 countries. Associations with risk factors were assessed by Poisson regression and summarised by prevalence rate ratios (PRRs).RESULTS: Extensive pain (i.e. at six or more of the 10 anatomical sites examined) was much more prevalent than would have been expected by chance coincidence. In comparison with limited pain (i.e. at 1-3 sites), extensive pain showed distinctive associations with demographic characteristics and a much stronger relation to somatising tendency (PRR 4.6, 95%CI 3.5-6.1 v 1.3, 95%CI 1.2-1.4) and reported heavy physical loading (PRR 5.0, 95%CI 2.8-9.2 v 1.4, 95%CI 1.2-1.6). It also varied differently between occupational groups. Thus, for example, nurses in Spain had the highest rate of limited pain (64.3%), but one of the lowest rates of extensive pain (3.5%). In contrast, the prevalence of extensive pain among office workers in Nicaragua was 14.0%, whereas that of limited pain was only 40.4%.CONCLUSIONS: Extensive musculoskeletal pain has different determinants from pain affecting fewer anatomical sites. Its prevalence varies substantially between occupations and countries, and in a different way from limited pain. In research on causes of pain at specific anatomical sites, it may be important to distinguish cases with pain only at the site of interest from those with pain also at multiple other sites