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.