Samuel F. Dworkin

Grading the severity of chronic pain.

&NA; This research develops and evaluates a simple method of grading the severity of chronic pain for use in general population surveys and studies of primary care pain patients. Measures of pain intensity, disability, persistence and recency of onset were tested for their ability to grade chronic pain severity in a longitudinal study of primary care back pain (n = 1213), headache (n = 779) and temporomandibular disorder pain (n = 397) patients. A Guttman scale analysis showed that pain intensity and disability measures formed a reliable hierarchical scale. Pain intensity measures appeared to scale the lower range of global severity while disability measures appeared to scale the upper range of global severity. Recency of onset and days in pain in the prior 6 months did not scale with pain intensity or disability. Using simple scoring rules, pain severity was graded into 4 hierarchical classes: Grade I, low disability‐low intensity; Grade II, low disability‐high intensity; Grade III, high disability‐moderately limiting; and Grade IV, high disability‐severely limiting. For each pain site, Chronic Pain Grade measured at baseline showed a highly statistically significant and monotonically increasing relationship with unemployment rate, pain‐related functional limitations, depression, fair to poor self‐rated health, frequent use of opioid analgesics, and frequent pain‐related doctor visits both at baseline and at 1‐year follow‐up. Days in Pain was related to these variables, but not as strongly as Chronic Pain Grade. Recent onset cases (first onset within the prior 3 months) did not show differences in psychological and behavioral dysfunction when compared to persons with less recent onset. Using longitudinal data from a population‐based study (n = 803), Chronic Pain Grade at baseline predicted the presence of pain in the prior 2 weeks, Chronic Pain Grade and pain‐related functional limitations at 3‐year follow‐up. Grading chronic pain as a function of pain intensity and pain‐related disability may be useful when a brief ordinal measure of global pain severity is required. Pain persistence, measured by days in pain in a fixed time period, provides useful additional information.

An epidemiologic comparison of pain complaints

&NA; A survey concerning common pain conditions and psychological distress was carried out among a probability sample of the adult enrollees of a large health maintenance organization in Seattle. The prevalence of pain in the prior six months was 41% for back pain; 26% for headache; 17% for abdominal pain; 12% for chest pain; and 12% for facial pain. Headache, abdominal and facial pain were less prevalent among older persons and more prevalent among females. We examined the temporal dimensions of these pain conditions, as well as intensity, treatment seeking, and activity limitation. The pain conditions were typically long standing, recurrent, of mild to moderate intensity, and usually did not limit activities. However, depending on the pain condition, 9–40% reported one or more days in the prior six months when they were unable to carry out their usual activities due to the pain problem. On average, persons with a pain condition had higher levels of anxiety, depression, and non‐pain somatic symptoms as measured by the scales of the Symptom Checklist (SCL); poorer self‐rating of health status; and more family stress compared to persons without a pain condition. Of these alternative measures of distress, the SCL somatization scale had the strongest independent association with pain. The increments in measures of anxiety, depression, and family stress with the presence of pain were greatest among persons with higher levels of non‐pain somatic symptoms.

Graded chronic pain status: an epidemiologic evaluation

&NA; In epidemiologic research on chronic pain, differentiation of recurrent, persistent and disabling pain states is critical in the investigation of burden, natural history, effective intervention and causal processes. We report population‐based data concerning the development and evaluation of a graded classification of pain status. In a probability sample of 1016 health maintenance organization enrollees, recurrent or persistent pain was observed in 45%; severe and persistent pain in 8%; severe and persistent pain with 7 or more days of pain‐related activity limitation in 2.7%; and severe, persistent pain with activity limitation and 3 or more indicators of pain dysfunction in 1.0% of the population sample. Graded chronic pain status was associated with psychological impairment, unfavorable appraisal of health status, and frequency of use of pain medications and health care. The presence of severe and persistent pain increased the likelihood of multiple indicators of pain dysfunction, but there was considerable heterogeneity in pain dysfunction among persons with comparable pain experience. Our data suggest grading chronic pain in terms of 3 axes: time (persistence); severity; and impact (disability and dysfunctional illness behaviors).

Changes in temporomandibular pain and other symptoms across the menstrual cycle

&NA; The objective of this study was to assess changes in levels of clinical temporomandibular (TMD) pain in relation to phases of the menstrual cycle. TMD cases were 35 women not using oral contraceptives (OCs); 35 women using OCs; and 21 men. Controls were 35 normally cycling women without TMD or other chronic pains. Subjects kept daily diaries over three menstrual cycles, reporting average and worst pain, general and premenstrual symptoms. Data were subject‐centered and de‐trended using the residuals from a random‐effects linear regression model. To test for cyclic variation, cycles were standardized to 28 days and data were grouped into 9 periods/cycle (Days 1–3, 4–6,…, 22–24, 25–28). Overall levels of average pain, worst pain and symptoms did not differ across TMD subject groups. For worst pain, multivariate analysis of variance revealed a statistically significant difference across 3‐day periods for normally cycling women with TMD (P=0.011) and for women using OCs (P=0.017). In both groups, TMD pain levels rose toward the end of the cycle and peaked during menstruation. In women not using OCs, there was a secondary pain peak at Days 13–15, around the time of ovulation. This peak was not seen in women using OCs. There was no statistically significant difference over time periods for men (P=0.94). Similar patterns were found for average pain, as well as PMS symptoms and general somatic symptoms. These results suggest that TMD pain in women is highest at times of lowest estrogen, but rapid estrogen change may also be associated with increased pain.

Use of exogenous hormones and risk of temporomandibular disorder pain.

Abstract Temporomandibular disorders (TMD) are common pain conditions that have their highest prevalence among women of reproductive age. The higher prevalence of TMD pain among women, pattern of onset after puberty and lowered prevalence rates in the post‐menopausal years suggest that female reproductive hormones may play an etiologic role in TMD. Two epidemiologic studies were designed to assess whether use of exogenous hormones is associated with increased risk of TMD pain. Both used data from automated pharmacy records of women enrolled in a large health maintenance organization to identify prescriptions filled for post‐menopausal hormone replacement therapies (Study 1) or for oral contraceptives (OCs) (Study 2). Study 1 employed an age‐matched case‐control design to compare post‐menopausal hormone use among 1291 women over age 40 referred for TMD treatment and 5164 controls not referred. After controlling for health services use, the odds of being a TMD case were approximately 30% higher among those receiving estrogen compared to those not exposed (P=0.002); a clear dose‐response relationship was evident. The relationship of progestin use to TMD was not statistically significant. Study 2 used a similar design to examine the relationship of OC use to referral for TMD care, drawing on data from 1473 cases and 5892 controls aged 15–35. Use of OCs was also associated with referral for TMD care, with an increased risk of TMD of approximately 20% for OC users, after controlling for health services use (P<0.05). These results suggest that female reproductive hormones may play an etiologic role in orofacial pain. This relationship warrants further investigation through epidemiologic, clinical and basic research.

First onset of common pain symptoms: a prospective study of depression as a risk factor

&NA; This report examined first onset rates of 5 common pain symptoms and assessed, on a prospective basis, whether depressive symptoms at baseline were associated with onset risks. Adult Health Maintenance Organization (HMO) enrollees (n = 1016) were interviewed in 1986 about their history of each of 5 pain conditions (back pain, severe headache, chest pain, abdominal pain and temporomandibular disorder (TMD) pain). Three years later, this sample was re‐interviewed (n = 803) to measure site‐specific first onset rates. The Symptom Checklist 90‐Revised (SCL‐90‐R) Depression scale was administered at baseline and at 3 year follow‐up. Over the three year follow‐up interval, rates of first onset were: 17.7% for back pain; 4.2% for severe headache; 3.0% for chest pain; 3.1% for abdominal pain; and 6.5% for TMD pain. Onset rates of persistent pain and of chronic pain dysfunction were substantially lower, but over 1% experienced onset of chronic pain dysfunction for back pain and for headache. There were not significant differences in onset rates of back pain, abdominal pain or TMD pain by severity or chronicity of depressive symptoms. Relative to the non‐depressed, persons with moderate‐to‐severe depressive symptoms were more likely to develop headache and chest pain (adjusted odds ratios of 1.7 to 5.0). For headache and chest pain, onset risks were highest among the chronically depressed. After adjusting for age, gender, education and depression severity, persons with a pain condition at baseline were more likely to report first onset of a new pain condition over the follow‐up period (adjusted odds ratios of 2.1 for back pain, 4.3 for headache, 1.4 for chest pain, 6.3 for abdominal pain and 3.7 for TMD pain). Thus, presence of a pain condition was a more consistent predictor of subsequent risks of developing a new pain condition than was the severity or chronicity of depressive symptoms. Possible explanations for this relationship are considered.

Review of aetiological concepts of temporomandibular pain disorders: towards a biopsychosocial model for integration of physical disorder factors with psychological and psychosocial illness impact factors

Several studies have reported that musculoskeletal disorders of the stomatognathic system, commonly known as temporomandibular disorders (TMD) resemble musculoskeletal disorders and chronic pain disorders in general. There is also general consensus that combined biomedical and biopsychosocial methods best support the assessment and management of the cardinal features of TMD, i.e., pain and dysfunction or physical (peripheral) and psychosocial (central) factors. This overview of the aetiology of TMD will outline conceptualizations of past models and present the current view that patients with TMD should be assessed according to both the physical disorder and the psychosocial illness impact factors. The conceptual theories outlined in this review include biomedical models related to temporomandibular joints, muscles of mastication and occlusal factors, psychological models and the biopsychosocial models. An integrated and multidimensional approach concerning physical and psychosocial factors in temporomandibular pain and dysfunction is presented as an example of how the biopsychosocial model and information processing theory may apply in the conceptualization and management of TMD for various health care professionals.

Human pain responsivity in a tonic pain model: psychological determinants.

&NA; Human pain responsivity was defined as the subjects behavioral pain endurance time (PET) to the 1 ± 0.3°C cold‐pressor test, a naturalistic and clinical analogue tonic pain model. Over the past 2 years, we have consistently observed a behavioral dichotomy of pain responsivity in each of our 6 studies (all at P < 0.000001 effect level), totaling 205 subjects. Overall, the pain‐tolerant (PT) subjects could endure the whole 5 min (note that 3 min was the ceiling criterion in the last study) of cold‐pressor test, while the pain‐sensitive (PS) subjects could merely tolerate the test for an overall mean of 60 sec, 20% of PET in the PT group. No overlapping of distribution was observed between these 2 populations. Further, we observed that the percentage of subjects in each of these 2 groups varied substantially across studies. The mean pain perception (Visual Analogue Scale) of tonic pain ranged from 60–70 for both aversiveness and intensity scales. The characteristics of this tonic pain, assessed by the McGill Pain Questionnaire (MPQ), showed similar patterns across each study with a high degree of consistency. Although ratings of pain aversiveness did not differ in the PT vs. PS subjects, ratings of pain intensity did differ, with the PT subject reporting less pain. It was found that state anxiety correlated with MPQ scores for PS, but not PT, subjects. Additionally, psychological tests (Tellegen Absorbance Scale, Kleinknecht Fear, Spielberger Trait‐Anxiety) were positively correlated with certain MPQ measures for PS, but not PT subjects. Multivariate regression analyses indicated, in the PS but not the PT group, that 36% of variance in pain score (MPQ‐T) could be predicted by the psychological trait factors. The general level of fear contributed singularly as the major predictor variable in the pain‐sensitive individuals. We consider this tonic pain model indeed offers a succinct empirical paradigm to study human pain responsivity in general. The psychological/physiological etiology of such drastic human pain responsivity requires intense systematic investigations. This report discusses the results in: (a) individual differences in pain responsivity, (b) characterization of the cold‐pressor test as a model for tonic pain, (c) contrast between PS and PT groups of pain perception and state anxiety, and (d) psychological determinants of measures for cognitive, perceptual and affective domains. Discussion was also focused on the experimental tonic pain model and its generality for clinical pain, as well as the basic model of the cold‐pressor test for human tonic pain responsivity.

Assessing clinical signs of temporomandibular disorders: Reliability of clinical examiners

Data on interrater reliability in assessing a number of clinical signs commonly evaluated in the diagnosis and treatment of temporomandibular disorders (TMD) is presented in this article. Four experienced dental hygienists who were field examiners for a large epidemiologic study of TMD and three experienced clinical TMD specialists (dentists) who are coinvestigators in the same study followed carefully detailed specifications and criteria for examination of TMD patients and pain-free controls. Excellent reliability was found for vertical range of motion measures and for summary indices measuring the overall presence of a clinical sign that could arise from several sources (for example, summary indices of muscle palpation pain). However, many clinical signs important in the differential diagnosis of subtypes of TMD were not measured with high reliability. In particular, assessment of pain in response to muscle palpation and identification of specific temporomandibular joint sounds seemed to be possible only with modest, sometimes marginal, reliability. These modest reliabilities could arise from examiner error because the clinical signs are themselves unreliable, changing spontaneously over time and making it difficult to find the same sign on successive examinations. The finding that, without calibration, experienced clinicians showed low reliability with other clinicians suggests the importance of establishing reliable clinical standards for the examination and diagnostic classification of TMD.

Reliability of clinical temporomandibular disorder diagnoses.

&NA; Temporomandibular disorders (TMD) diagnoses can be viewed as the most useful clinical summary for classifying subtypes of TMD. The Research Diagnostic Criteria for TMD (RDC/TMD) is the most widely used TMD diagnostic system for conducting clinical research. It has been translated into 18 languages and is used by a consortium of 45 RDC/TMD‐based international researchers. While reliability of RDC/TMD signs and symptoms of TMD has been amply reported, the reliability of RDC/TMD diagnoses has not. The aim of the study was to determine the reliability of clinical TMD diagnoses using standardized methods and operational definitions contained in the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Data came from reliability assessment trials conducted at 10 international clinical centers, involving 30 clinical examiners assessing 230 subjects. Intraclass correlation coefficients (ICC) were calculated to characterize the reliability. The reliability of the diagnoses was fair to good. Median ICCs for the diagnoses myofascial pain with and without limited opening were 0.51 and 0.60, respectively. Median ICC for arthralgia was 0.47 and 0.61 for disc displacement with reduction. RDC/TMD diagnoses of disc displacement without reduction, osteoarthritis and osteoarthrosis were not prevalent enough to calculate ICCs, but percent agreement was always >95%. The reliability of diagnostic classification improved when diagnoses were grouped into pain versus non‐pain diagnoses (ICC=0.72) and for detecting any diagnosis versus no diagnosis (ICC=0.78). In clinical decision‐making and research, arriving at a reliable diagnosis is critical in establishing a clinical condition and a rational approach to treatment. The RDC/TMD demonstrates sufficiently high reliability for the most common TMD diagnoses, supporting its use in clinical research and decision making.