Clinical classes of injured workers with chronic low back pain: a latent class analysis with relationship to working status
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To determine (a) clinical classes of injured workers with chronic low back pain (CLBP), (b) predictors of class membership and (c) associations of classes with baseline work status.
Patients with CLBP from a tertiary care outpatient clinic in Toronto, Canada were sampled. Latent class analysis was applied to determine class structure using physical, psychological and coping indicators. Classes were interpreted by class-specific means and analyzed for predictors of membership. Lastly, association of the classes with being off work was modeled.
A 3-class model was chosen based on fit criteria, theoretical and clinical knowledge of this population. The resultant 3 classes represented low, moderate and high levels of clinical severity. Predictors of being in the high severity group compared to the low severity group were < high school education [odds ratio (OR) 3.06, 95% CI (1.47, 6.37)] and comorbidity total [OR 1.28, 95% CI (1.03, 1.59)]. High severity class membership was associated with four times increased risk of being off work at baseline compared to those in the low severity group [OR 3.98, 95% CI (1.61, 6.34)].
In a cohort of injured workers with CLBP, 3 clinical classes were identified with distinct psychological and physical profiles. These profiles are useful in aiding clinicians to identify patients of high clinical severity who may be potentially at risk for problematic return to work.
KeywordsLow back injury Workers Latent variable mixture model Clinical classes
The authors acknowledge Darlene Stafford, Registered Physiotherapist, Clinical Practice Leader, Back and Neck Specialty Program, Altum Health, University Health Network and Rajiv Gandhi MD, Manager of Outcomes Measure and Reporting Team, Altum Health, University Health Network, for the assistance in data acquisition. LC was funded by a Fellowship from the Canadian Institutes of Health Research.
Compliance with ethical standards
Conflict of interest
None of the authors has any potential conflict of interest.
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