Outcome prediction in chronic unilateral lumbar radiculopathy: prospective cohort study

BACKGROUND: Identification of prognostic factors for persistent pain and disability are important for better understanding of the clinical course of chronic unilateral lumbar radiculopathy and to assist clinical decision-making. There is a lack of scientific evidence concerning prognostic factors. The aim of this study was to identify clinically relevant predictors for outcome at 52 weeks. METHODS: 116 patients were included in a sham controlled clinical trial on epidural injection of glucocorticoids in patients with chronic unilateral lumbar radiculopathy. Success at follow-up was ≤17.5 for visual analogue scale (VAS) leg pain, ≤22.5 for VAS back pain and ≤20 for Oswestry Disability Index (ODI). Fifteen clinically relevant variables included demographic, psychosocial, clinical and radiological data and were analysed using a logistic multivariable regression analysis. RESULTS: At follow-up, 75 (64.7%) patients had reached a successful outcome with an ODI score ≤20, 54 (46.6%) with a VAS leg pain score ≤17.5, and 47 (40.5%) with a VAS back pain score ≤22.5. Lower age (OR 0.94 (CI 0.89–0.99) for each year decrease in age) and FABQ Work ≥34 (OR 0.16 (CI 0.04-0.61)) were independent variables predicting a successful outcome on the ODI. Higher education (OR 5.77 (CI 1.46–22.87)) and working full-time (OR 2.70 (CI 1.02–7.18)) were statistically significant (P <0.05) independent predictors for successful outcome (VAS score ≤17.5) on the measure of leg pain. Lower age predicted success on ODI (OR 0.94 (95% CI 0.89 to 0.99) for each year) and less back pain (OR 0.94 (0.90 to 0.99)), while higher education (OR 5.77 (1.46 to 22.87)), working full-time (OR 2.70 (1.02 to 7.18)) and muscle weakness at baseline (OR 4.11 (1.24 to 13.61) predicted less leg pain, and reflex impairment at baseline predicted the contrary (OR 0.39 (0.15 to 0.97)). CONCLUSIONS: Lower age, higher education, working full-time and low fear avoidance beliefs each predict a better outcome of chronic unilateral lumbar radiculopathy. Specifically, lower age and low fear avoidance predict a better functional outcome and less back pain, while higher education and working full-time predict less leg pain. These results should be validated in further studies before being used to inform patients. TRIAL REGISTRATION: Current Controlled Trials ISRCTN12574253. Registered 18 May 2005.