Musculoskeletal pain in other body sites is associated with new-onset low back pain: a longitudinal study among survivors of the great East Japan earthquake

BACKGROUND: Low back pain (LBP) is a common health problem experienced after natural disasters. LBP is often concurrent with other musculoskeletal pain; however, the effects of preexisting musculoskeletal pain on the development of LBP are not clear. The purpose of this study was to elucidate the association of musculoskeletal pain in other body sites with new-onset LBP among survivors of the Great East Japan Earthquake (GEJE). METHODS: A longitudinal study was conducted with survivors of the GEJE. The survivors who did not have LBP at the 3 year time period after the GEJE were followed up 1 year later (n = 1782). Musculoskeletal pain, such as low back, hand and/or foot, knee, shoulder, and neck pain, were assessed with self-reported questionnaires. The outcome of interest was new-onset LBP, which was defined as LBP absent at 3 years but present at 4 years after the disaster. The main predictor was musculoskeletal pain in other body sites 3 years after the GEJE, which was categorized according to the number of pain sites (0, 1, ≥ 2). Multiple regression analyses were performed to calculate the odds ratio (OR) and 95% confidence interval (CI) for new-onset LBP due to musculoskeletal pain in other body sites. RESULTS: The incidence of new-onset LBP was 14.1% (251/1782). Musculoskeletal pain in other body sites was significantly associated with new-onset LBP. Including people without other musculoskeletal pain as a reference, the adjusted OR and 95% CI for new-onset LBP were 1.73 (1.16–2.57) for people with one musculoskeletal pain site and 3.20 (2.01–5.09) for people with ≥ 2 sites (p < 0.001). CONCLUSIONS: Preexisting musculoskeletal pain in other body sites was associated with new-onset LBP among survivors in the recovery period after the GEJE.