Two-week test-retest stability of the cold pressor task procedure at two different temperatures as a measure of pain threshold and tolerance.

BACKGROUND The cold pressor task (CPT) was originally developed as a clinically indicative cardiovascular test, and quantifies vascular response and pulse excitability when a subject's hand is immersed into ice water. Since the test procedure results in a gradually increasing cold pain, the CPT has been widely used as a nociceptive stimulus in experimental studies on adults and children. AIM To evaluate the test-retest stability of response patterns using the CPT as a measure of pain threshold and pain tolerance. MATERIALS AND METHODS In the present study, sixty-one undergraduate students received painful stimulation using the CPT either at 4°C or 6°C. Measurements of pain threshold, pain tolerance and pain intensity ratings using the short form of the McGill pain questionnaire (SF-MPQ), were derived. The assessment was repeated twice over an interval of 2 weeks. Test-Retest stability was assessed within a three-layered approach, using ANOVAs, interclass correlation coefficients and standard error of the mean. A Bland-Altman analysis was also performed. Possible predictors of pain threshold and pain tolerance were assessed using random effect panel regression models. RESULTS No significant differences emerged as a function of temperature (4°C or 6°C) on pain threshold, pain tolerance, and pain ratings. Environmental variables (room temperature and humidity) show no impact on measures of pain threshold and pain tolerance. CONCLUSION Consistent with previous findings, regression analysis reveals that age is significantly associated with pain tolerance. The CPT procedure shows excellent 2 week test-retest stability to assess pain threshold and pain tolerance within a student population.