Predictors of short-term work-related disability among active duty US Navy personnel: a cohort study in patients with acute and subacute low back pain

Abstract

Musculoskeletal disorders of the spine in the US military account for the single largest proportion of the absence of sickness causes leading to early termination. We explored if selected psychological and physical factors were associated with poor outcome after episodes of low back pain (LBP). To identify clinical, demographic, and psychological factors predictive of work duty status after a complaint of LBP. A prospective clinical cohort of US Navy personnel treated for LBP. Eligible cases were active duty US Navy or Marine Corps personnel presenting to an emergency clinic or primary care clinic with a complaint of LBP, where the index episode of LBP was no more than 12 weeks duration before enrollment. The subject's work status (full duty, light duty, sick in quarters [SIQ], limited duty, or medically released to full duty) was abstracted from the subject's electronic medical record at approximately 4 weeks and then again 12 weeks after study enrollment. Work status in this study population is assigned by a Navy health-care provider at the time of a clinical visit and based on the health-care provider's determination of medical fitness for duty. This study collapsed work status into two groups, "full duty" (consisting of "full duty" and "medically released to full duty") and "not at full duty" (consisting of "light duty," "SIQ," and "limited duty"). Volunteers completed a baseline questionnaire consisting of recommended well-validated measures, including attitudes and beliefs about LBP and work (Fear-Avoidance Beliefs Questionnaire [FABQ] and the Tampa Scale of Kinesiophobia), distress (the Pain Catastrophizing Scale), clinical depression (The Center for Epidemiologic Studies Depression scale), a numeric pain intensity scale, self-perceived disability (Oswestry Disability Index), and general health status (12-Item Short Form Health Survey). Navy health-care providers conducted a back pain-specific medical evaluation. Associations are expressed as multivariate-adjusted prevalence ratios (PRs) estimated using Poisson regression. Two hundred fifty-three participants were enrolled. Work status outcome was collected for 239 participants. Predictors of "not at full duty" at 4 weeks after enrollment included having back pain for 4 weeks or less before study enrollment (PR, 2.69; 95% CI, 1.21-5.97) and increased FABQ Work subscale score (PR, 1.05; 95% CI, 1.01-1.08). The sole predictor of work status at 12 weeks after enrollment was increased FABQ Physical Activity (FABQ Physical) subscale score (PR=1.14; 95% CI, 1.00-1.30). The findings that fear-avoidance beliefs were predictive of subsequent work status among active duty service personnel in this study population (after adjusting for clinical, demographic, and psychological covariates) suggest the clinical utility of addressing these factors during treatment of back pain episodes in the military. These findings reflect the important role that psychological factors may play in the return to work process in an active duty military population.