Spotlight on NIDCR:
Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA)
In December 2013, the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) published its latest findings in a supplemental issue of the Journal of Pain. Folded into eight original articles and a summary paper, the new data present the most in-depth picture to date of the factors that may contribute to a person developing an initial bout of a painful temporomandibular disorder, or TMD.
Launched in 2006, OPPERA I has followed 2,737 healthy men and women to see who develops TMD and why. At enrollment, participants were between the ages of 18 and 44, asymptomatic of TMD, and had no history of the condition. The latest data are based on a median 2.8 years of follow up and, as the second wave of data from OPPERA I, are referred to as OPPERA I, Act II. Also of note, OPPERA is the first natural history study of a chronic pain condition.
Among the findings from OPPERA I, Act II is a total of 260 participants developed their first case of painful TMD during followup. This translates to an incidence rate of 4 percent per year. Using a novel method of multivariable analysis, which evaluates contributions from 202 phenotypic variables simultaneously, the researchers discovered a range of phenotypic risk factors influenced first onset TMD. These included sociodemographic characteristics, health status, clinical orofacial factors, psychological functioning, pain sensitivity, and cardiac autonomic responses. Variables within the health status domain made the greatest contribution, followed closely by psychological and clinical orofacial domains. Interestingly, only a few measures of pain sensitivity and autonomic function contributed to TMD incidence, and their effects were modest. In addition, age was an independent predictor of TMD incidence, even after controlling for other phenotypes. Separate analysis of 358 genes that regulate pain found several novel genetic associations with intermediate phenotypes that, in themselves, are risk factors for TMD. This suggests new avenues to investigate biological pathways contributing to TMD. To read a more detailed interview with two OPPERA scientists, visit: