Predicting the outcome of persistent sciatica using conditioned pain modulation: 1-year results from a prospective cohort study

Background and aims Recovery in patients hospitalised with severe sciatica is unpredictable. Prognostic tools to aid clinicians in the early identification of patients at risk of developing chronic sciatic pain are warranted. Conditioned pain modulation (CPM) is a psychophysical measure of the endogenous pain modulatory pathways. Several studies have suggested CPM as a potentially important predictive biomarker for the development of chronic pain. The aim of the study was to determine whether CPM effect in patients still suffering from leg pain 6 weeks after hospital discharge for severe sciatica is associated with persistent leg pain at 12 months. A potential association would suggest that measuring CPM effect could be a valuable prognostic tool in the hospital management of sciatica. Methods A prospective cohort study in which CPM effect was measured 6 weeks after hospital discharge following an acute admission with sciatica as the main complaint. The impact of CPM effect on the outcome was analysed using logistic regression. The outcome measured was self-reported leg pain score of ≥1 in the past week on a 0-10 numeric rating scale (NRS) at 12 months post discharge. Results A total of 111 patients completed the entire study, 51 of whom received non-randomised surgical...