Pain sensitivity and autonomic factors associated with development of TMD: The OPPERA prospective cohort study

Multiple studies report that individuals with chronic temporomandibular disorder (TMD) have enhanced sensitivity to experimental pain. Additionally, chronic TMD cases show altered autonomic function, including elevated heart rate and reduced heart rate variability. However, causal inferences regarding the association between TMD and pain sensitivity and autonomic function cannot be drawn from these cross-sectional observations. The prospective Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) study examines whether measures of pain sensitivity or cardiac autonomic function provide predictive value in TMD incidence. A cohort of 2,737 initially TMD-free participants was followed for up to 5.2 years, during which time 260 developed first-onset TMD. Fourteen of 39 experimental pain measures produced significant hazard ratios, such that greater pain sensitivity was associated with greater TMD incidence. A single autonomic measure - heart rate at rest - was also associated significantly with greater TMD incidence. In contrast, using the same measures of pain sensitivity and cardiac autonomic function, we previously reported a larger group of variables that was significantly associated with chronic TMD in the OPPERA case-control study. Future studies should investigate whether premorbid pain sensitivity or autonomic function more specifically predicts risk of developing chronic TMD than first-onset TMD. Perspective: Our previous case-control studies showed that associations with both pain sensitivity and cardiac autonomic function are profound in chronic TMD cases. Here we show that some measures of enhanced pain sensitivity contribute modestly to the risk of developing TMD whereas autonomic dysregulation appears to confer little or no risk for TMD incidence.