Predictors for outcome in acute lateral epicondylitis

BACKGROUND: Lateral epicondylitis or tennis elbow is a frequent condition with long-lasting symptoms. In order to identify predictors for treatment success and pain in lateral epicondylitis, we used data from a randomized controlled trial. This trial investigated the efficacy of physiotherapy alone or combined with corticosteroid injection for acute lateral epicondylitis in general practice. METHODS: The outcomes treatment success and pain score on VAS were assessed at 6, 12, 26 and 52 weeks. We ran a univariate binary logistic regression with generalized estimating equations (GEE) and subsequently an adjusted multilevel logistic regression to analyze the association between potential prognostic indicators and the outcome success/ no success. To assess the changes in pain score we used a two-level multilevel linear regression (MLR) followed by an adjusted MLR model with random effects. RESULTS: The most consistent predictor for reduced treatment success at all time points was a high Pain Free Function Index score signifying more pain on everyday activities. Being on paid sick-leave and having a recurring complaint increased short term treatment success but gave decreased long-term treatment success. The patients reporting symptoms after engaging in probable overuse in an unusual activity, tended towards increased treatment success at all time-points, but significant only at 12 weeks. The most consistent predictor of increased pain at all time points was a higher overall complaints score at baseline. CONCLUSIONS: Our results suggest that in treating acute lateral epicondylitis, a consideration of baseline pain, a registration of the patient's overall complaint on a VAS scale and an assessment of the patient's perceived performance in everyday activities with the Pain Free Function Index can be useful in identifying patients that will have a more protracted and serious condition. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00826462 . Date of registration January 22, 2009. The Trial was prospectively registrated.