Last month we began our report on findings in OPPERA's Act Two," the second series of analyses of data from the Orofacial Pain Prospective Evaluation and Risk Assessment (OPPERA) study, which enrolled healthy volunteers at four campus sites in Chapel Hill, NC; Baltimore; MD; Buffalo, NY; and Gainesville, FL. Follow-up questionnaires were available from 2,737 enrollees, and clinical examinations in the course of the study documented that 260 of these people developed first-onset TMD. This month we report on their initial signs and symptoms, their sociodemographic characteristics (such as age, gender, and socioeconomic status), and their psychological profiles.
Symptoms. To be classified as a first-onset TMD case, individuals had to report orofacial pain for 5 or more days in the prior 30 days and show clinical evidence of jaw muscle pain (myalgia), jaw pain (arthralgia), or both. Two-thirds of the new patients reported "recurrent bouts" of facial pain or headache and one-fifth reported persistent pain in the preceding two weeks before examination. Painful jaw symptoms were described as ache, soreness or tenderness; non-painful jaw symptoms most frequently were stiffness or fatigue. Pain levels were at the lower ends of scales of intensity, disability or unpleasantness, and a quarter of patients said they had headache only. However, when examined clinically using measures of pain on jaw opening and on applying pressure (palpation) at fixed levels on the joint, the various chewing muscles and sites elsewhere in the body, 60 patients had myalgia alone, 10 had arthralgia alone and 190 had both jaw and muscle pain. Nearly all patients reported pain when sites on the neck or elsewhere in the body were palpated.
Sociodemographics. Interestingly, almost as many men as women were diagnosed with first-onset TMD in contrast with what has generally been reported in epidemiological surveys of the population at large and certainly in studies of patients with chronic TMD, where women greatly outnumber men. Researchers speculate that the difference may lie in the greater likelihood that women will transition from acute to chronic TMD, and that might entail a role for female hormones. Greater age and lifetime residence in the U.S. were also associated with a greater incidence of TMD. The greater age incidence, which was more pronounced in racial minorities, is consistent with earlier OPPERA studies, which also reflect the greater accumulation of general health problems with age. Why lifetime residence in the U.S. is associated with greater incidence of TMD might be explained by the finding that foreign-born immigrants generally have better health outcomes than native-born residents for a range of diseases (a phenomenon called the "healthy immigrant effect") while U.S. residents who have lived abroad for some time probably reflect a segment of the population in good health. In terms of race/ethnicity, Asian-Americans showed a lesser incidence and African-Americans a greater incidence of first-onset TMD compared to Caucasians. However, when asked about socioeconomic status, African-Americans reported higher levels of dissatisfaction with their material status, and this negative perception (which was not associated with actual measures of education and income) might well be a factor in contributing to TMD incidence.
Psychological profile. At the outset of the study, questionnaires were used to measure enrollees' general psychological adjustment and personality, levels of stress, pain coping mechanisms, and reactions to pain such as the degree to which individuals imagines that the worst will happen to them, dwelling on and magnifying their pain and feeling helpless (called pain "catastrophizing"). Two tests also measured somatization or somatic awareness, an individual's report of a variety of body symptoms such as nausea, fatigue, or dizziness thought to reflect cognitive or psychological processes. The phenomenon has sometimes been called hypervigilance.
Results. Somatization turned out to be the phenomenon most highly predictive of first-onset TMD as measured by one of the two tests of somatic symptoms called the "PILL." High scores on another test, a 90-item Symptom Checklist (SCL), in which participants were asked to rate (using a five-point scale) how much a particular symptom bothered them - from from not at all to extremely bothered - was predictive of TMD. The SCL includes a measure of somatization but also includes scales measuring obsessive-compulsive tendencies, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation and psychoticism.
Patients were queried about whether they had experienced any one of 15 traumatic events. Those who responded yes to at least one event were then asked to rate the degree of stress associated with a civilian 17-item post-traumatic stress disorder checklist. Researchers found that a greater degree of PTSD symptoms was also associated with TMD incidence.
High scores of perceived stress, anxiety, neuroticism, impact of negative events and negative affect (overall emotional state) were all associated with development of TMD but in relatively modest terms. In contrast, positive affect and extraversion as a measure of personality were associated with decreased rates of TMD. Neither pain coping mechanisms nor catastrophizing were statistically significant predictors of TMD, probably, as the researchers suggested, because these tests were administered at the time of enrollment before the individual developed TMD.
By Joan Wilentz, The TMJ Association
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