Sleep disturbances predict long-term changes in low back pain among Finnish firefighters: 13-year follow-up study

PURPOSE To investigate the prevalence of low back pain among Finnish firefighters and to examine whether sleep disturbances predict membership of low back pain trajectories. METHODS In this prospective study, 360 actively working firefighters responded to a questionnaire in 1996, 1999 and 2009. The outcome variables were radiating and local low back pain during the preceding year. Using logistic regression modeling, the likelihood of membership of pain trajectories was predicted by sleep disturbances at baseline. RESULTS During the 13-year follow-up, the prevalence of radiating low back pain increased from 16 to 29 % (p < 0.0001) and that of local low back pain from 28 to 40 % (p < 0.001). The following trajectories were identified: "pain free," "recovering," "new pain," "fluctuating" and "chronic." More than one-fifth of the participants belonged to the new pain trajectory as regards both pain types, 6 % of the participants belonged to the chronic radiating and 12 % to the chronic local low back pain trajectory. Those with sleep disturbances at baseline had a 2.4-fold risk (adjusted OR 2.4; 95 % CI 1.2-4.7) of belonging to the new pain or chronic radiating pain cluster compared to pain-free participants. CONCLUSIONS This is the first prospective study to show that low back symptoms are common and persistent among firefighters and that sleep disturbances strongly predict membership of a radiating pain trajectory. Occupational health and safety personnel, as well as the firefighters themselves, should recognize sleep problems early enough in order to prevent back pain and its development into chronic pain.