Predictors of stable return-to-work in non-acute, non-specific spinal pain: low total prior sick-listing, high self prediction and young age. A two-year prospective cohort study

Background Non-specific spinal pain (NSP), comprising back and/or neck pain, is one of the leading disorders in long-term sick-listing. During 2000-2004, 125 Swedish primary-care patients with non-acute NSP, full-time sick-listed 6 weeks-2 years, were included in a randomized controlled trial to compare a cognitive-behavioural programme with traditional primary care. This prospective cohort study is a re-assessment of the data from the randomized trial with the 2 treatment groups considered as a single cohort. The aim was to investigate which baseline variables predict a stable return-to-work during a 2-year period after baseline: objective variables from function tests, socioeconomic, subjective and/or treatment variables. Stable return-to-work was a return-to-work lasting for at least 1 month from the start of follow-up. Methods Stable return-to-work was the outcome variable, the above-mentioned factors were the predictive variables in multiple-logistic regression models, one per follow-up at 6, 12, 18 and 24 months after baseline. The factors from univariate analyzes with a p-value of at most .10 were included. The non-significant variables were excluded stepwise to yield models comprising only significant factors (p < .05). As the comparatively few cases made it risky to associate certain predictors with certain time-points, we finally considered the predictors which were represented in at least 3 follow-ups. They are presented with odds ratios (OR) and 95% confidence intervals. Results Three variables qualified, all of them represented in 3 follow-ups: Low total prior sick-listing (including all diagnoses) was the strongest predictor in 2 follow-ups, 18 and 24 months, OR 4.8 [1.9-12.3] and 3.8 [1.6-8.7] respectively, High self prediction (the patients' own belief in return-to-work) was the strongest at 12 months, OR 5.2 [1.5-17.5] and Young age (max 44 years) the second strongest at 18 months, OR 3.5 [1.3-9.1]. Conclusions In primary-care patients with non-acute NSP, the strong predictors of stable return-to-work were 2 socioeconomic variables, Low total prior sick-listing and Young age, and 1 subjective variable, High self-prediction. Objective variables from function tests and treatment variables were non-predictors. Except for Young age, the predictors have previously been insufficiently studied, and so our study should widen knowledge within clinical practice. Trial registration Trial registration number for the original trial NCT00488735.