Predictors of outcome in lateral epicondylalgia, which is mainly characterized as a mechanical hyperalgesia, are largely limited to sociodemographic and symptomatic factors. Quantitative sensory testing is used to study altered pain processing in various chronic pain conditions and may be of prognostic relevance.
The predictive capacity of early measures of physical and psychological impairment on pain and disability and mechanical hyperalgesia, were examined using data from 41 patients assigned to placebo in a prospective randomized controlled trial of unilateral lateral epicondylalgia. Quantitative sensory testing (pressure, cold pain thresholds), motor function (pain-free grip), and psychological factors (Tampa Scale of Kinesiophobia, Hospital Anxiety and Depression Scale) were measured at baseline. The outcome measures were the Patient-rated Tennis Elbow Evaluation (PRTEE) scale and pressure pain threshold (PPT) measured by digital algometry at the affected elbow. Backward stepwise linear regression was used to predict PRTEE and PPT scores at 2 and 12 months.
Cold pain threshold was the only consistent predictor for both PRTEE (P<0.034) and PPT (P<0.048). Initial PRTEE was the strongest single predictor of PRTEE at 2 months, whereas female sex was the strongest single predictor of PPT (P<0.002). At 1 year, final models explained 9% to 52% of the variability in pain and disability and mechanical hyperalgesia, respectively.
Early assessment of cold pain threshold could be a useful clinical tool to help identify patients at risk of poorer outcomes and might provide direction for future research into mechanism-based treatment approaches for these patients.