Pain response classification does not predict long-term outcome in patients with low back pain who are sick-listed

Prospective cohort study nested in a randomized clinical trial.

To investigate the prognostic value of pain response classification at initial physiotherapy examination in patients with low back pain (LBP) who are sick-listed.

Recurrent and chronic LBP accounts for a substantial proportion of all absence from work. In predicting outcome in patients with LBP, psychosocial factors are thought to play an important role, while findings from clinical examination seem to be of more limited value. Mechanical evaluation, using repeated end range spinal movements that result in specific pain responses, has been shown to be of some value.

The study included 351 patients sick-listed because of LBP with or without sciatica. Prior to clinical examination, the patients completed a comprehensive questionnaire including questions on pain, function, and psychosocial factors. The physiotherapy examination included a standardized mechanical evaluation. Patients were classified into 3 groups according to their pain response: centralization, peripheralization, or no response. Outcomes were obtained by national register data, medical records, and a postal questionnaire at 1 year.

At 1-year follow-up, 65% of the patients had returned to work. All pain response groups showed significant and clinically important improvements in both pain and disability. No significant differences were found between pain response groups in any outcome measure. Results remained unchanged after adjustment for potential confounders.

The prognostic value of pain response classification seems limited in patients sick-listed from work because of LBP.