The Impact Of Pain Testing Familiarization On Pain Perception

Quantitative sensory testing (QST) provides an effective means to better understand the pain process for better pain management. Due to individual differences within the pain experience, QST demonstrates large variability across patients. Testing techniques such as familiarization of pain testing methods may provide an avenue by which to reduce such variation. PURPOSE: The purpose of this study was to determine if pain testing familiarization impacts subsequent pain testing scores both within and across multiple pain testing sessions. METHODS: 25 participants (13(m)/12(f); 22.5 ± 2.5 yrs) underwent 4 separate training sessions. Participants underwent a familiarization trial immediately followed by two trials of experimental testing within each session. Familiarization testing included pressure pain threshold (PPT), pressure pain tolerance (PPTs), heat threshold (HT), heat tolerance (Htol), and heat 50 (H50). Experimental testing following familiarization included all the same tests except the Htol test to avoid sensitizing the subjects. Familiarization was conducted on the subject's non-dominant leg at midthigh followed by experimental testing on the same location of a randomized leg. RESULTS: No significant differences were seen in PPT (trial - F(3,384) = 0.08, p = 0.972; session - F(3,384) = 1.23, p = 0.298) and the PPTs (trial - F(3,384) = 0.60, p = 0.615; session - F(3,384) = 0.327, p = 0.806) tests when comparing familiarization with testing trials or across sessions. HT demonstrated a significant main effect (trial - F(3,384) = 3.05, p = 0.029; session - F(3,384) = 1.82, p = 0.142) however post-hoc analysis produced no significant differences of note. Finally, the H50 did produce significantly lower temperatures after familiarization within a given trial (F(3,384) = 45.8, p < 0.000) as well as differences were seen across sessions (F(3,384) = 3.92, p = 0.009). CONCLUSION: When testing for moderate levels of heat pain, familiarization should be considered. Based on the results of this study, the use of familiarization may be dependent on the type of stimulus and may not be necessary for all types of pain stimuli. More research is still needed in order to support or deny the need for familiarization to be included in pain testing research to increase the accuracy of future research studies.