Experimental Pain Sensitivity in Subjects with Temporomandibular Disorders and Multiple Other Chronic Pain Conditions: The OPPERA Prospective Cohort Study

Aims: To investigate associations between experimental pain sensitivity and five chronic pain conditions among 655 participants in the OPPERA study. Methods: Quantitative sensory tests were used to measure sensitivity to three modalities of nociception: blunt pressure pain, mechanical pinprick pain, and thermal heat pain. Participants were also classified according to the presence or absence of five chronic pain conditions: temporomandibular disorders, headache, low back pain, irritable bowel syndrome, and fibromyalgia. Results: Univariate analyses found each modality to be significantly associated with at least one pain condition, most consistently for pressure pain sensitivity (8 of 15 instances) and least consistently for heat pain sensitivity (5 of 35 instances). Yet, multivariable analyses that evaluated the independent contributions of all five pain conditions found few significant associations (12 of 75 instances). Instead, pain sensitivity consistently varied according to the total number of pain conditions a person experienced, implying that the combination of pain conditions influences each nociceptive modality. Conclusion: When evaluating nociceptive sensitivity in a chronic pain patient, comorbid pain conditions should be considered, as the more salient feature underlying sensitivity is likely the number rather than the type(s) of pain conditions. Keywords: chronic overlapping pain conditions, heat pain, pinprick pain, pressure pain, quantitative sensory testing