Statistical significance, clinical importance and effect sizes: Enhancing understanding of a study's results.

BACKGROUND: The proper interpretation of a study's results requires both excellent understanding of good methodological practices and deep knowledge of prior results, aided by the availability of effect sizes. METHODS: This review takes the form of an expository essay exploring the complex and nuanced relationships among statistical significance, clinical importance, and effect sizes. RESULTS: Careful attention to study design and methodology will increase the likelihood of obtaining statistical significance and may enhance the ability of investigators/readers to accurately interpret results. Measures of effect size show how well the variables used in a study account for/explain the variability in the data. Studies reporting strong effects may have greater practical value/utility than studies reporting weak effects. Effect sizes need to be interpreted in context. Verbal summary characterizations of effect sizes (e.g., "weak", "strong") are fundamentally flawed and can lead to inappropriate characterization of results. Common language effect size (CLES) indicators are a relatively new approach to effect sizes that may offer a more accessible interpretation of results that can benefit providers, patients, and the public at large. CONCLUSIONS: It is important to convey research findings in ways that are clear to both the research community and to the public. At a minimum, this requires inclusion of standard effect size data in research reports. Proper selection of measures and careful design of studies are foundational to the interpretation of a study's results. The ability to draw useful conclusions from a study is increased when investigators enhance the methodological quality of their work.

Dental practitioner approaches to bruxism: Preliminary findings from the national dental practice-based research network.

OBJECTIVE: Bruxism is a repetitive masticatory muscle activity. This study investigates dental practitioners' approaches to bruxism assessment and treatment in practices. METHODS: A brief 5 question questionnaire ("Quick Poll") on bruxism was conducted. RESULTS: A total of 397 practitioners responded. More than half (55%) initiated treatment for bruxism on one to three patients per month. The majority believed that stress (97%) and sleep patterns (82%) affected bruxism in their patients. Interestingly, 96% offered an occlusal guard/appliance and 46% made occlusal adjustments. CONCLUSION: This study highlights inconsistencies in practitioner approaches to bruxism assessment and management in clinical settings, suggesting gaps in practitioner knowledge evidenced by the varied responses. ABBREVIATIONS: PBRN - Practice-Based Research NetworkMMA - Masticatory muscle activitySB - Sleep bruxismAB - Awake bruxismTMJ - Temporomandibular jointOSA - Obstructive sleep apnea.

Jaw Exercises in the Treatment of Temporomandibular Disorders-An International Modified Delphi Study.

AIMS: To investigate whether an international consensus exists among TMD experts regarding indications, performance, follow-up, and effectiveness of jaw exercises. METHODS: A questionnaire with 31 statements regarding jaw exercises was constructed. Fourteen international experts with some geographic dispersion were asked to participate in this Delphi study, and all accepted. The experts were asked to respond to the statements according to a 5-item verbal Likert scale that ranged from "strongly agree" to "strongly disagree." The experts could also leave free-text comments, which was encouraged. After the first round, the experts received a compilation of the other experts' earlier responses. Some statements were then rephrased and divided to clarify the essence of the statement. Subsequently, the experts were then asked to answer the questionnaire (32 statements) again for the second round. Consensus was set to 80% agreement or disagreement. RESULTS: There is consensus among TMD experts that jaw exercises are effective and can be recommended to patients with myalgia in the jaw muscles, restricted mouth opening capacity due to hyperactivity in the jaw closing muscles, and disc displacement without reduction. The patients should always be instructed in an individualized jaw exercise program and also receive both verbal advice and written information about the treatment modality. CONCLUSION: This Delphi study showed that there is an international consensus among TMD experts that jaw exercises are an effective treatment and can be recommended to patients with TMD pain and disturbed jaw function.

The Sinhala version of the pain catastrophizing scale: validation and establishment of the factor structure in pain patients and healthy adults.

OBJECTIVE: This study was conducted to translate the Pain Catastrophizing Scale into and adapt it to the Sinhala language and to examine its psychometric properties and factor structure in pain patients and healthy adults in Sri Lanka. SETTING AND DESIGN: A cross-sectional study was conducted, recruiting pain patients from multiple clinics and healthy adults from the community as convenience samples. METHODS: Cross-cultural adaptation of the Pain Catastrophizing Scale for Sinhala speakers was carried out using recommended methods. The adaptation's psychometric properties and factor structure were tested in 149 pain patients and 172 healthy adults. Temporal stability was tested in a sample of 104 young adults. Pain intensity of patients was assessed using a visual analog scale, and personality traits of all participants were assessed with the Eysenck Personality Questionnaire. RESULTS: Factor analysis revealed that the three-factor structure of the original version of the Pain Catastrophizing Scale was the best fit to the data from participant samples. Cronbach's alpha values of the three components and total scores for patients and healthy adults ranged from 0.72 to 0.87. Pain catastrophizing exhibited moderate positive correlations with neuroticism in patients and healthy adults and with pain intensities in patients. A high intraclass correlation coefficient of agreement (0.81) revealed an acceptable temporal stability in young adults. CONCLUSIONS: The results suggest that the Sinhala version of the Pain Catastrophizing Scale retains the original three-factor structure. It is a stable, valid and sufficiently reliable tool to assess pain catastrophizing in Sinhala-speaking individuals in Sri Lanka.

Headache and oral parafunctional behaviors.

This study tested the hypotheses that individuals with headaches would show significantly more oral parafunctional behaviors than non-headache controls, be diagnosed with one or more temporomandibular disorders (TMD) significantly more frequently than controls, and would report significantly less pain and other symptoms of headache after participating in a habit reversal treatment to reduce oral parafunctional behaviors, compared to a wait list control. In Phase I, individuals with and without self-reported headaches were examined by a blinded examiner and participated in a week-long experience sampling protocol (ESM) to assess oral parafunctional behaviors, pain, and emotional states. In Phase II, those with headaches were randomly assigned to either a habit reversal treatment or to a wait list control group. In the last, sixth week of the program, participants again completed an ESM protocol. Results showed that headache patients were significantly more likely to report oral parafunctional behaviors than non-headache controls and to receive a Research Diagnostic Criteria/TMD diagnosis. Results from Phase II showed general improvement in both groups on pain and parafunctions. Individuals with headaches engage in significantly higher rates and intensities of oral parafunctional behaviors. Treatment of these behaviors using habit reversal techniques appears to have the same effect on pain as waiting.

Exercise during pregnancy: the role of obstetric providers.

CONTEXT: Obstetric providers are logical choices for conveying information about physical activity to their pregnant patients. However, research regarding obstetric providers counseling pregnant patients about physical activity is sparse. OBJECTIVES: To investigate the association between obstetric providers discussing exercise with their pregnant patients and patients' exercise behaviors and to explore factors related to obstetric providers discussing exercise and other health behaviors (tobacco use, alcohol use, and nutrition) with their patients. METHODS: We received completed surveys from 238 pregnant women and 31 obstetric providers at 12 obstetrician offices. The offices were located throughout the United States and were heterogeneous in regards to patient insurance coverage, number of patients treated per month, and percentage of patients with complications. RESULTS: Women who were "more careful about eating healthy" (odds ratio [OR], 3.1; 95% confidence interval [CI], 1.2-8.0) and who discussed exercise with their obstetric provider (OR, 2.2; 95% CI, 1.1-4.3) were more likely to "maintain or increase exercise" during pregnancy than those who were not conscientious about their diets and those who did not discuss exercise with their obstetric provider, respectively. The odds of obstetric providers discussing exercise with pregnant patients increased 7-fold (OR, 7.1; 95% CI, 1.4-37.3) for each health behavior the obstetric provider discussed with the patient. CONCLUSION: Patient discussions with obstetric providers about exercise and patient attention to eating habits are associated with exercising during pregnancy. A more multibehavioral approach by obstetric providers may improve the likelihood that patients exercise during pregnancy.

Autonomic dysregulation in headache patients.

To analyze autonomic nervous system activity in headache subjects, measurements of heart rate variability (HRV), skin temperature, skin conductance, and respiration were compared to a matched control group. HRV data were recorded in time and frequency domains. Subjects also completed self-report questionnaires assessing psychological distress, fatigue, and sleep dysfunction. Twenty-one headache and nineteen control subjects participated. In the time domain, the number of consecutive R-to-R intervals that varied by more than 50 ms and the standard deviation of the normalized R-to-R intervals, both indices of parasympathetic nervous system activity, were significantly lower in the headache group than the control group. Groups did not differ statistically on HRV measures in the frequency domain. Self-report measures showed significantly increased somatization, hostility, anxiety, symptom distress, fatigue, and sleep problems in the headache group. The results suggest headache subjects have increased sympathetic nervous system activity and decreased parasympathetic activity compared to non-headache control subjects. Headaches subjects also showed greater emotional distress, fatigue, and sleep problems. The results indicate an association between headaches and cardiovascular functioning suggestive of sympathetic nervous system activation in this sample of mixed migraine and tension-type headache sufferers.

Development of a quality-assessment tool for experimental bruxism studies: reliability and validity.

AIMS: To combine empirical evidence and expert opinion in a formal consensus method in order to develop a quality-assessment tool for experimental bruxism studies in systematic reviews. METHODS: Tool development comprised five steps: (1) preliminary decisions, (2) item generation, (3) face-validity assessment, (4) reliability and discriminitive validity assessment, and (5) instrument refinement. The kappa value and phi-coefficient were calculated to assess inter-observer reliability and discriminative ability, respectively. RESULTS: Following preliminary decisions and a literature review, a list of 52 items to be considered for inclusion in the tool was compiled. Eleven experts were invited to join a Delphi panel and 10 accepted. Four Delphi rounds reduced the preliminary tool-Quality-Assessment Tool for Experimental Bruxism Studies (Qu-ATEBS)- to 8 items: study aim, study sample, control condition or group, study design, experimental bruxism task, statistics, interpretation of results, and conflict of interest statement. Consensus among the Delphi panelists yielded good face validity. Inter-observer reliability was acceptable (k = 0.77). Discriminative validity was excellent (phi coefficient 1.0; P < .01). During refinement, 1 item (no. 8) was removed. CONCLUSION: Qu-ATEBS, the seven-item evidence-based quality assessment tool developed here for use in systematic reviews of experimental bruxism studies, exhibits face validity, excellent discriminative validity, and acceptable inter-observer reliability. Development of quality assessment tools for many other topics in the orofacial pain literature is needed and may follow the described procedure.

Ocular problems in low-income and minority children.

PURPOSE: To report the prevalence rates of screen failures for uncorrected refractive error, abnormal or excessive levels of hyperopia, problems in binocular vision, and deficiency of near point acuity as related to age and ethnicity in children. METHODS: Vision screening tests were administered to 9,743 African-American, Hispanic, and white children aged 6 to 11 years in the Kansas City (United States) metropolitan area. Screening was performed by health professions students using HOTV charts for refractive errors, hyperopia, and near point acuity and a Random Dot E test for binocular vision. Children were screened in their elementary schools, located in primarily poor, urban neighborhoods. The main outcome measure was pass/fail outcomes from screenings, with confirmation of screen fails by licensed health care professionals. RESULTS: For African-American children, 14.1% failed one or more vision screening tests. The corresponding screen failure rates for Hispanic and white children were 14.2% and 11.0%, respectively. There were significant differences in screening failure rates as a function of age and ethnicity, depending on the specific test. The highest rates of screen failures occurred in the 9 to 11 year old age range. CONCLUSIONS: Vision screening failures were frequently associated with age and ethnicity. Screening performed by health professions students can successfully identify potential visual problems at rates similar to those reported in studies using more complex, sophisticated testing performed by specially trained individuals.

Establishing the content validity of palpatory examination for the assessment of the lumbar spine using ultrasonography: a pilot study.

CONTEXT: Practitioners of manipulative medicine have long sought to prove the intra- and interexaminer reliability of palpatory examinations in assessing somatic dysfunction. However, decades of research have yet to achieve the level of reproducibility needed to satisfy evidence-based criteria. OBJECTIVES: To examine the content validity of segmental motion evaluations using ultrasonographic measurements and to investigate the implication of these results for understanding the effects of an osteopathic manipulative treatment technique--high-velocity, low-amplitude (HVLA)--applied to somatic dysfunction in the lumbar spine. METHODS: A repeated-measures design was used, with the ultrasonographer blinded to the findings for each participant. The study was divided into 2 phases: (1) palpatory and ultrasonographic examination with no treatment and (2) palpatory and ultrasonographic examination with HVLA treatment. During phase 1, measurements were taken of tissue depth corresponding to bony landmarks of the dysfunctional vertebrae. Dysfunction was identified by means of palpatory examination and captured in sequential (ie, test-retest) ultrasonographic images. Content validity of somatic dysfunction was addressed by comparing palpatory examination with ultrasonographic data. During phase 2, the same protocol for tissue depth measurements was applied to the pre- and posttreatment images for comparison. RESULTS: Twelve young, healthy, asymptomatic students with no contraindications to HVLA treatment were recruited at Kansas City University of Medicine and Biosciences. The test-retest reliability, as determined by a Pearson correlation coefficient, was 0.997. For all participants, objectively identified side of dysfunction correlated with palpatory evaluation of segmental motion. A within-subjects analysis of variance was performed on the raw data, corrected for lumbar lordosis, showing statistical significance for main effect for side of measurement (P<.001) and interaction of side and time (P<.001), and showed no statistically significant effect for time (P=.259). CONCLUSION: Ultrasonography is a reliable instrument for the assessment of somatic dysfunction of the lumbar spine. The data also establish the content validity of palpatory examinations. In addition, this study provides the first objective evidence, to our knowledge, of the effect of a thrusting manipulative treatment on dysfunctional lumbar vertebrae.

Tooth contact versus clenching: oral parafunctions and facial pain.

AIMS: To test the hypothesis that estimates of time spent in tooth contact are significantly greater than estimates of time spent clenching, and to test the hypothesis that tooth contact is greater in pain patients, particularly those reporting facial or head pain, than those with pain elsewhere in the body. METHODS: An anonymous, voluntary, confidential questionnaire was administered to 235 patients seeking care at a general medical clinic. The questionnaire assessed demographic variables, presence and location of pain, and percentage of time spent in tooth contact and in clenching. Analysis of variance was used to examine differences among groups of patients; logistic regression was used to identify significant predictors of pain. RESULTS: All patients reported that the percentage of time spent in tooth contact was significantly greater than the time spent clenching. The same pattern of results emerged for those with and without head pain, and those with and without any chronic pain problem. Both tooth contact and clenching were significantly associated with head pain. CONCLUSION: Results from the logistic regressions provide convergent validity on the importance of oral parafunctions, specifically tooth contact and clenching, to facial/head pain. For assessment of oral parafunctional behaviors, inquiries that utilize clear behavioral referents (tooth contact versus clenching) are likely to result in more accurate estimates than behaviors with unclear definitions.

Randomized clinical trials: is periodontal research good for patients?

Randomized controlled trials, in which randomization is used to allocate patients to a treatment arm, are a relatively new concept. Randomized controlled trials are increasingly high-stakes endeavors requiring a high level of planning and considerable financial support. Randomized controlled trials are the gold standard by which effectiveness of various treatments or interventions are determined. However, the methods involved in randomized controlled trials raise the question: is clinical research good for the participants? This paper discusses patient-centered issues relating to randomized controlled trials, for example, whether the informed-consent process results in subjects who are knowledgeable and informed about their participation, which, in turn, involves patient autonomy, health literacy and treatment preferences. Other issues discussed are those of statistical vs. clinical significance, professional ethics and ethical justification for randomized controlled trials, and differences in perceptions between patients and clinicians regarding the level of care being provided by the randomized controlled trials. Because our goal, as clinicians, is to provide treatment that improves the quality of life for the patient, it would seem logical that randomized controlled trials should include variables rated as important by patients as valid outcome measures. As clinicians and researchers, we can no longer afford to view randomized controlled trials from an ivory tower. Research participants, although autonomous agents, are inherently different from the patient seeking clinical care. Researchers have an ethical responsibility to consider the informed consent process as it relates to the subject's health literacy and potential for therapeutic and procedural misperceptions.

Anatomic changes related to laryngeal descent from birth to 1 year of age: do they play a role in SIDS?

We conducted a retrospective study to measure laryngeal descent in human infants and to determine if there is any correlation between the associated anatomic changes and the timing of the peak incidence of sudden infant death syndrome (SIDS), which is 2 to 4 months of age. We performed a computerized search of hospital records at our institution to identify magnetic resonance imaging (MRI) scans of the head and neck and plain radiographs of the lateral neck in patients younger than 1 year of age (range: 1 to 357 days). After unusable images were excluded, 79 head and neck MRI scans and 111 lateral neck x-rays were suitable for study. Two measurements were taken from each image: one from the tip of the epiglottis to the uvula and one from the tip of the epiglottis to the center of the sella turcica. These measurements were then graphed against the subject's age. SPSS statistical software was used to determine growth curves of the various measurements. The first derivative of these curves was calculated to determine the rate of laryngeal descent at a given age. We found that most subjects did not have an overlapping epiglottis and uvula during the first few months of life. The rate of laryngeal descent, based on measurements of the distance between the epiglottis and uvula, gradually increased in a near-linear fashion from as low as 0.005726 mm/day at day 1 of life to as high as 0.028366 mm/day at 300 days of age. We found no sharp increase in the rate of descent at 2 to 4 months of age, and thus no support for our hypothesis that there might be a correlation between anatomic changes and the peak incidence of SIDS.

Aerobic exercise during pregnancy influences fetal cardiac autonomic control of heart rate and heart rate variability.

BACKGROUND: Previous studies using ultrasound technology showed that fetal heart rate (HR) may be responsive to maternal aerobic exercise. Although it is recognized that cardiac autonomic control may be influenced by the intrauterine environment, little is known about how maternal exercise affects fetal heart development. AIMS: This study tested the hypothesis that regular maternal exercise throughout gestation influences fetal cardiac autonomic control of HR and heart rate variability (HRV) when compared to fetuses of non-exercising women. STUDY DESIGN: Magnetocardiograms (MCGs) were recorded using a dedicated fetal biomagnetometer at 28, 32 and 36 weeks gestational age (GA) from 26 regularly exercising (>30 min of aerobic exercise, 3x per week) and 35 healthy, non-exercising pregnant women. Fetal MCG was isolated and normal R-peaks were marked to derive fetal HR and HRV in the time and frequency domains. We applied a mixed-effects model to investigate the effects of exercise, GA and fetal activity state. RESULTS: At 36 weeks GA, during the active fetal state, fetal HR was significantly lower in the exercise group (p=<0.0006). Post-hoc comparisons showed significantly increased HRV in the exercise group during the active fetal state at 36 weeks GA for both time and frequency domain measures. CONCLUSION: These results indicate that regular maternal exercise throughout gestation results in significantly lower fetal HR and increased HRV.

Pharmacokinetics of concurrent administration of fosamprenavir and atazanavir without ritonavir in human immunodeficiency virus-negative subjects.

STUDY OBJECTIVE: To quantify the pharmacokinetics of amprenavir and atazanavir (administered as the prodrug fosamprenavir) alone and in combination in human immunodeficiency virus (HIV)-negative subjects. DESIGN: Randomized, open-label, three-way crossover study. SETTING: Research facility. PARTICIPANTS: Eleven men and 10 women who were seronegative for HIV. INTERVENTION: Subjects were randomized to 14-day treatment periods of fosamprenavir 1400 mg once/day, atazanavir 400 mg once/day, or fosamprenavir 1400 mg plus atazanavir 400 mg once/day; after a washout period of at least 21 days between each treatment, they received the other two treatments. MEASUREMENTS AND MAIN RESULTS: Subjects underwent 24-hour pharmacokinetic sampling at baseline and on day 14 of each treatment period. Primary outcome measures were area under the plasma concentration-time curve (AUC) and maximum concentration (C(max)) for amprenavir and atazanavir. Atazanavir significantly enhanced the exposure of amprenavir. When fosamprenavir was given alone, the geometric mean of amprenavir's AUC was 20.2 microg x hour/ml (95% confidence interval [CI] 19.1-21.2 microg x hr/ml). When given in combination with atazanavir, amprenavir had an AUC of 39.8 microg x hour/ml (95% CI 38.7-40.9 microg x hr/ml). Similarly, the C(max) for amprenavir increased from 4193 ng/ml (95% CI 3927-4459 ng/ml) to 6621 ng/ml (95% CI 6427-6814 ng/ml) when given in combination with atazanavir. In contrast, AUC and C(max) for atazanavir significantly decreased when atazanavir was coadministered with fosamprenavir; AUC decreased from 17.6 microg x hour/ml (95% CI 16.6-18.7 microg x hr/ml) to 11.8 microg x hour/ml (95% CI 11.3-12.3 microg x hr/ml), and C(max) decreased from 2507 ng/ml (95% CI 2379-2635 ng/ml) to 1832 ng/ml (95% CI 1752-1911 ng/ml). Adverse events were assessed at each study visit and 1 month after the subjects completed the three treatments. Both drugs were well tolerated. One serious adverse event (grade 3 acute pancreatitis) occurred and resolved without further incident. CONCLUSION: Atazanavir 400 mg/day plus fosamprenavir 1400 mg/day significantly decreased concentrations of atazanavir compared with standard dosing regimens of each drug alone. This dosing scheme is not a recommended combination of dual, fully active protease inhibitors.

Short-term hematologic and hemodynamic effects of osteopathic lymphatic techniques: a pilot crossover trial.

CONTEXT: Research into the physiologic effects of osteopathic lymphatic techniques has been somewhat limited. OBJECTIVE: To assess the short-term hematologic and hemodynamic effects of a comprehensive lymphatic treatment protocol. METHODS: Randomized crossover design that included 10-minute lymphatic treatment and rest (control) protocols delivered 1 week apart for a small pilot group of healthy men (N=15). At baseline, albumin, hematocrit, hemoglobin and platelet count , total protein, and white blood cell count were measured, as were systolic and diastolic blood pressure. All measures were repeated 20, 50, and 80 minutes after baseline data were gathered. RESULTS: Significant condition x time interaction effects were observed, indicating a decrease in platelet counts and an increase in diastolic blood pressure after the lymphatic treatment protocol [corrected]. Statistically significant differences by time were observed in all hemotologic measures and in systolic blood pressure. No adverse events or complications from the treatment protocol were observed in this population. CONCLUSION: Lymphatic techniques may decrease platelet counts and increase diastolic blood pressure during the first hour after treatment.

Temporomandibular disorders and facial pain: a psychophysiological perspective.

This article presents a psychophysiological perspective on temporomandibular muscle and joint disorders (TMJD) and facial pain. After a brief introduction to TMJD, the article presents data, largely derived from work carried out in my laboratory, that address four questions: (1) What are the consequences of parafunctional activities? (2) Do TMJD patients engage in parafunctional activities? (3) Why are TMJD patients unaware of these activities? and (4) What are the implications of these findings for treatment? The findings suggest that low-level parafunctions increase pain in otherwise pain-free individuals and can produce symptoms sufficiently severe to meet the diagnostic criteria for TMJD diagnoses of myofascial pain and/or arthralgia. Patients with certain forms of TMJD report very high levels of parafunctional tooth contact. Their lack of awareness of these behaviors may arise from uncertain definitions of the term "clenching", from proprioceptive deficits, or from the presence of adjunctive behaviors. Preliminary work shows that reduction in tooth contact via habit reversal techniques may be a promising mechanism for reducing pain in these patients.

"One pill, once daily": what clinicians need to know about Atriplatrade mark.

As the number of persons chronically prescribed antiretrovirals has grown and the realization that antiretrovirals are required to be continued for life, pharmaceutical manufacturers have developed new classes of agents, improved the pharmacokinetics of marketed products through dosing reformulations, and in an effort to maximize success with respect to adherence, compiled into a single dosing unit all necessary elements for an antiretroviral regimen. Atriplatrade mark represents the first ever fixed-dose combination antiretroviral available. This article reviews currently available data on this agent, the impact of resistance on clinical use and implementation, as well as extensive descriptions of the pharmacokinetics, adverse effects and drug-interactions warranting consideration. Whether beginning in a naïve patient or switching from other regimens for tolerability issues, Atriplatrade mark represents a viable option. Its demonstrated advantages with respect to lipid and hematologic parameters and equivalent incidence of renal toxicity are tempered by the findings of bone mineral density decreases, however. Combining multiple mechanisms of action in a single dosing unit appears to improve efficacy, increase the likelihood for adherence and maintain viral suppression compared to administering these agents independently. It is suggested other pharmaceutical companies assess the potential to replicate this for the remaining antiretrovirals.

Diurnal variation in pain reports in temporomandibular disorder patients and control subjects.

AIMS: To test the hypothesis that temporomandibular disorder (TMD) patients have characteristic diurnal patterns of pain that are associated with diurnal or nocturnal parafunctions. METHODS: Experience sampling methods were used to obtain information on pain from subjects (n = 84) diagnosed, according to the Research Diagnostic Criteria for TMD, with myofascial pain, myofascial pain and arthralgia, disc displacement, and from non-TMD controls. Variations in pain as reported on the pager questionnaire form were modeled as linear, exponential, and quadratic effects. RESULTS: Between 8.7% and 23.8% of TMD subjects with pain showed significant patterns to their daily pain reports, compared to 4.5% of non-TMD controls. Groups did not differ significantly in the proportions of those with increasing (59.5%) vs. decreasing (40.5%) pain levels. Self-reported clenching during the day and grinding at night were weakly associated with an increasing or decreasing pattern of pain during the day (P < .10). Pain levels during weekends were significantly lower for all groups. CONCLUSIONS: Strongly linear or curvilinear patterns of pain were not characteristic of this sample of subjects. More than half the subjects reported slightly increasing pain during the day, but the variability within groups was considerable. Increasing and decreasing patterns of pain were independent of self-reported daytime and nighttime clenching and grinding. Self-reported pain patterns may not be used to reliably infer the times when parafunctional activities occur. The presence of lower pain levels during the weekend probably reflects reduction in psychosocial stressors associated with the work week.