Multivariable modeling of phenotypic risk factors for first-onset TMD: the OPPERA prospective cohort study

Incidence of temporomandibular disorder (TMD) was predicted with multivariable models that used putative risk factors collected from initially TMD-free individuals in the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) study. The 202 baseline risk factors included sociodemographic and clinical characteristics, measures of general health status, experimental pain sensitivity, autonomic function, and psychological distress. Study participants (n = 2,737) were then followed prospectively for a median of 2.8 years to ascertain cases of first-onset TMD. Lasso regression and random forest models were used to predict incidence of first-onset TMD using all of the aforementioned measures. Variable importance scores identified the most important risk factors, and their relationship with TMD incidence was illustrated graphically using partial dependence plots. Two of the most important risk factors for elevated TMD incidence were greater numbers of comorbid pain conditions and greater extent of nonspecific orofacial symptoms. Other important baseline risk factors were preexisting bodily pain, heightened somatic awareness, and greater extent of pain in response to examiners' palpation of the head, neck, and body. Several demographic variables persisted as risk factors even after adjusting for other OPPERA variables, suggesting that environmental variables not measured in OPPERA may also contribute to first-onset TMD.

Perspective: Multivariable methods were used to identify the most important predictors of first-onset TMD in the OPPERA study. Important variables included comorbid pain conditions, preexisting pain, and somatic awareness. Demographic characteristics, which probably reflect environmental variables not measured in OPPERA, also appear to play an important role in the etiology of TMD.