Biofeedback-Based Cognitive Behavioral Treatment for Temporomandibular Disorders

Characteristic pain intensity (German Pain Questionnaire; Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD)):

Characteristic pain intensity was calculated by averaging ratings of current pain, average pain, and worst pain in the past month on a numeric rating scale from 0 (no pain) to 10 (maximum pain), as recommended by RDC/TMD (range 0 - 10). Higher values indicate higher pain levels.

Pain related disability was assessed using the Pain Disability Index (PDI). The PDI is a brief self-rating scale which assesses the level of pain related disability in seven areas of daily life (e.g., social activity, self-care) on a 0 (no disability) -10 (maximum disability) numeric rating scale (range 0 - 70). Higher values indicate higher disability levels. Cronbach's alpha was .87 in the current sample.

Jaw use limitations were measured using the Jaw Disability List (JDL) from the RDC/TMD. The JDL asks the patient to rate interference with eleven oral activities, for example chewing or talking. We used an 11-point numeric rating scale (from 0 'no limitation' to 10 'maximum limitation') instead of ratings of 'yes' and 'no' (range 0 - 110). Higher values indicate higher levels of jaw use limitations. Cronbach's alpha was .86 in the current sample.

Somatoform complaints during the past week were assessed using the Screening for Somatoform Symptoms (SOMS-7). 32 medically unexplained symptoms (29 for male subjects) representing DSM-IV criteria for somatization disorder were rated on a 0 ('not at all') to 4 ('very much') scale (range 0 - 128 for women and 0 - 116 for men). A sum score was calculated with higher scores indicating higher intensity and burden of somatoform complaints. In the current sample, Cronbach's alpha level was α = .88.

Depressive symptoms were measured using the Centre for Epidemiological Studies Depression scale (CES-D). The CES-D asks for the frequency of 20 symptoms of depression during the past week on a scale ranging from 0 ('less than 1 day') to 3 ('5 to 7 days') (range 0-60). Higher scores indicate more depressive symptoms. It is suitable for use in chronic pain patients as it relies less on physical symptoms of depression than do other measures. Cronbach's alpha level in the current sample was α = .89.

General anxiety symptoms were assessed using the 7-item scale from the Patient Health Questionnaire (GAD-7). The GAD-7 asks for anxiety symptoms during the past month on a 1 ('not at all') to 3 ('more than half of the days') rating scale (range 7-21). Higher scores indicate higher levels of anxiety. Cronbach's alpha level in the current sample was α = .64.

Cognitive and behavioral pain coping strategies were assessed with Coping Strategies Scale from the German Pain Coping Questionnaire (Fragebogen zur Erfassung der Schmerzverarbeitung, FESV). The scale asks for the use of 24 cognitive (e.g. cognitive restructuring) and behavioral (e.g. use of relaxation techniques) strategies for coping with pain on a scale ranging from 1 ('fully disagree') to 6 ('fully agree') (range 24-144). A sum score was used with higher scores indicating more adaptive coping. Cronbach's alpha level was α = .80.

TMD related symptoms, such as jaw pain, toothache or dizziness, were measured using a 41-item TMD symptom list. Following the SOMS-7 scale, intensity of symptoms experienced during the past week was rated from 0 ('not at all') to 4 ('very high intensity') (range 0 - 164). A sum score was built with higher scores indicating higher intensity of TMD related symptoms. The TMD symptom list has not been evaluated previously; however, large bivariate correlations with somatization (Pearson's r = .79), medium to large correlations with pain intensity (r = .48), and medium correlations with depression (r = .37) and anxiety (r = .27) provide evidence of good convergent and divergent validity. Cronbach's alpha level in the current sample was excellent (α = .93).