Cold Hyperalgesia Associated with Poorer Prognosis in Lateral Epicondylalgia
Predictors of outcome in lateral epicondylalgia, which for the most part is characterised as a mechanical hyperalgesia, are largely limited to socio-demographic and symptomatic factors. Quantitative sensory testing is used to investigate altered pain processing in various chronic pain conditions and may be of prognostic relevance. The predictive potential of early measures of physical and psychological impairment on pain and disability and mechanical hyperalgesia, were studied using data from 41 patients assigned to placebo in a prospective randomised 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. Backwards stepwise linear regression was used to predict PRTEE and PPT scores at two and twelve months. The only consistent predictor for both PRTEE (P<0.034) and PPT (P<0.048) was cold pain threshold. Initial PRTEE was the most significant single predictor of PRTEE at 2 months, while being female was the most significant single predictor of PPT (P<0.002). At one year, final models explained 9 to 52% of the variability in pain and disability and mechanical hyperalgesia respectively.
The study found that early testing of cold pain threshold might be a useful clinical tool to assist in identifying patients at risk of poorer outcomes and could serve to give direction to future research into mechanism-based treatment approaches for these patients.