Test-retest Reliability in Reporting the Pain Induced by a Pain Provocation Test

Background: Pain drawings (PD) are frequently used in research to illustrate the pain response to pain provocation tests, however there is a lack of data on the reliability in defining the extent and location of pain. We investigated the test-retest reliability in reporting an acute painful sensation induced by a pain provocation test using a novel approach for PD acquisition and analysis in healthy volunteers. Methods: Forty healthy volunteers participated. Each participant underwent two Upper Limb Neurodynamic tests 1 (ULNT1), once to the point of pain onset (PO), and once until the point of submaximal pain (SP). After each ULNT1, participants completed two consecutive PD with an interval of one minute. Custom software was used to quantify the pain extent and analyse the pain overlap. The test-retest reliability of pain extent was examined using Intraclass Correlation Coefficient (ICC 2,1) and Bland-Altman plots. Pain location reliability was examined using the Jaccard Similarity Coefficient (JSC). Results: The ICC values for PO and SP were 0.98 (95% CI: 0.96–0.99), and 0.97 (95% CI: 0.95–0.98), respectively. The mean difference and 95% limits of agreement (± 1.96 SD) in the Bland-Altman plots were 14 pixels (-1080;1110) for PO, and 145 (-1610;1900) for SP. The median JSCs (Q1;Q3) were 0.73 (0.64;0.80) for PO, and 0.76 (0.65;0.79) for SP. Conclusions: PD is a reliable instrument to investigate pain extent and pain location in healthy individuals experiencing an acute painful sensation induced by a pain provocation test.