Method of Limit and Method of Level for Thermal and Pain Detection Assessment

Abstract

Background: Many patients referred for physical therapy have pain and somatosensory problems. Thermal quantitative sensory testing (QST) is used for assessing somatosensory function. Method of limits (MLI) and method of levels (MLE) are two commonly measurement methods used for thermal QST. A good measurement method for clinical application should be convenient and reliable. The purpose of this study was to compare the acceptability and reliability of the MLI and MLE. Methods: Twenty-eight healthy adults (14 males and 14 females) participated in a thermal QST test retest study. The types of the thermal QSTs included the Cold Detection Threshold (CDT), Warm Detection Threshold (WDT), Cold Pain Threshold (CPT), and Heat Pain Threshold (HPT). Participants were examined with thermal QST using the two methods (MLI and MLE), and then re-examined after one week. Both the relative reliability and absolute reliability were estimated. Results: The acceptability was better in the MLI than in the MLE. Many trials of the MLE was needed (the mean number of trials = 12.2; range from 7 to 27 trials). The relative reliability of the MLI and MLE were similar; the range of intraclass correlation coefficient were 0.65 to 0.88 and 0.69 to 0.86 for the MLI and MLE, respectively. However, the absolute reliability of the CDT, WDT, and HPT on the MLE were not as accurate as those on the MLI. Conclusion: When we compared the acceptability and reliability, the MLI was superior to the MLE. The MLI is recommended as useful method for measuring thermal and pain thresholds.