Prevalence, Predictors and Wage Replacement Duration Associated with Diagnostic Imaging in Australian Workers with Accepted Claims for Low Back Pain: A Retrospective Cohort Study.

Objectives To determine in Australian workers with an accepted workers' compensation claim for low back pain (LBP) (1) the prevalence of diagnostic imaging of the spine and factors associated with its use, and (2) the association between spinal diagnostic imaging events and wage replacement duration. Methods Workers with accepted workers' compensation claims for LBP longer than 2 weeks were grouped by whether workers' compensation funded no, single, or multiple diagnostic spinal imaging in the 2 years since reported LBP onset. Ordinal logistic regression was used to define the demographic, occupational and social factors associated with each group. Time-to-event analysis was used to determine the association between spinal imaging and wage replacement duration. Results In the sample of 30,530 workers, 9267 (30.4%) received single spinal imaging and 6202 (20.3%) received multiple spinal imaging. Male workers and workers from the state of Victoria had significantly higher odds of multiple imaging. Socioeconomically advantaged workers and workers from remote Australia had significantly lower odds of multiple imaging. Magnetic Resonance Imaging was the most common imaging modality. Workers with single spinal imaging (median duration 17.0 weeks; HR 2.0, 95% CI 1.9, 2.1) and multiple spinal imaging (median duration 49.0 weeks; HR 4.0, 95% CI 3.9, 4.1) had significantly longer wage replacement duration than those with no imaging (median duration 6.1 weeks). Conclusions Over half of Australian workers with an accepted workers' compensation claim for LBP longer than 2 weeks received diagnostic spinal imaging. Receipt of diagnostic imaging, particularly multiple imaging, was associated with longer wage replacement duration.