Assessing the Relationship Between Measures of Pain Sensitivity and Chronic Pain Conditions Comorbid with TMD: The OPPERA Case-Control Study

Roughly 1 in 20 people in the United States suffers from temporomandibular disorders (TMD), a set of disorders with symptoms ranging from mild jaw pain to chronic, debilitating pain. Prior research has indicated that patients with TMD may have more conditions comorbid to TMD (such as back pain or fibromyalgia), and experts have called for further work to increase awareness of a possible relationship between comorbid conditions and pain sensitivity. Using data from the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) project's case-control study, we address this problem. We used regression methods to determine if the number of painful comorbid conditions was associated with 33 different pain measures. We also adjusted for possible biases due to the sampling design using Inverse Probability Weighting (IPW) and also for multiple testing using Bonferroni adjustment. After these adjustments, we found that pressure pain measures were significantly associated with the number of comorbid conditions, but that in general other measures of pain sensitivity were not. Also, no association was detected when looking at cases versus controls individually. The surprising results that pain type had differential significance and that case status did not raises questions that warrant further research (alternatively, this may be due to decreased sample size to detect a difference between cases and controls). Despite this, there did exist conclusive results to suggest that, at least for pressure pain measures, there is a relationship between the number of comorbid conditions and pain sensitivity.