Reliability Of Pain Threshold Measurement In Young Adults

Abstract

IntroductionPrevious reports have demonstrated high intra-and interrater reliability for assessment of pressure pain thresholds (PPT) in clinical [1][2][3][4] and healthy subjects [5][6][7][8][9][10][11]. However, many of the earlier reliability analyses used Pearson's r correlation coefficient [e.g.; 5, 9-11]. Pearson's r is a measure of association, but is not appropriate for assessing agreement between raters or ratings, as it is not sensitive to systematic bias between raters (or ratings) [12][13][14]. The intra-class correlation (ICC) is a more appropriate measure as it is sensitive to systematic bias. The ICC can provide a measure of absolute agreement between raters, which answers the question of whether raters or ratings are interchangeable [12][13][14]. The coefficient of repeatability (CR), specified as 2 standard deviations of the mean test-retest differences [14], provides an estimate of retest ranges expressed in the measurement units. Hence, 95% of repeat measurements for the sample will be in the range: mean difference±CR. The coefficient of variation (CV) is specified as half of the CR expressed as a percentage of the mean [14]. ICC, CR and CV therefore provide complementary information on reliability.More recently, some studies of PPT reliability have used ICC to confirm reliability assessed by analogue algometers [15], electronic algometers [7,16] Stuart Cathcart Donald PritchardAbstract The objective was to examine reliability of pressure and thermal (cold) pain threshold assessment in persons less than 25 years of age, using intra-class correlation (ICC) and coefficients of repeatability and variability. We measured thresholds to pain from pressure algometry and ice placed at the hand and head in 10 healthy volunteers aged 18-25. Intra-rater reliability was examined with ICC. Coefficients of repeatability (CR) and variability (CV) were estimated. Reliability of repeat assessments was high as assessed by ICC, although coefficients of repeatability and variation indicated considerable inter-individual variation in repeat measurements. Pressure algometry and strategically placed ice appear to be reliable techniques for assessing pain processing in young adults. Reliability studies employing ICC may benefit from complementary estimation of CR and CV.