The research diagnostic criteria for temporomandibular disorders. IV: Evaluation of psychometric properties of the Axis II measures

Aims: To evaluate the psychometric properties of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) biobehavioral (Axis II) screening instruments. Methods: Participants with Axis I TMD diagnoses (n = 626) completed the Axis II instruments (Depression, Nonspecific Physical Symptoms, Graded Chronic Pain) and other instruments assessing psychological distress, pain, and disability at three study sites. Internal consistency, temporal stability, and convergent/ discriminant validity of the Axis II measures were assessed. To assess criterion validity of Nonspecific Physical Symptoms and Depression instruments as screeners, 170 participants completed a structured psychiatric diagnostic interview. Results: The Axis II instruments showed very good to excellent internal consistency (Cronbach's alpha coefficients = 0.80 to 0.95). Their convergent (correlation range 0.3 to 0.9) and discriminant (range 0.0 to 0.6) validity were generally supported, although Nonspecific Physical Symptoms was more strongly associated with depressive than with somatic symptoms. Temporal stability was high for characteristic pain intensity (Lin's correlation concordance coefficient [CCC] = 0.91), interference (CCC = 0.89), and chronic pain grade (weighted kappa = 0.87), and fair to good for Depression and Nonspecific Physical Symptoms (CCC = 0.63 to 0.78). The Depression instrument normal versus moderate to severe cutoff point was good at identifying current-year depression and dysthymia diagnoses (sensitivity 87%, specificity 53%). Nonspecific Physical Symptoms did not have high utility for detecting psychiatric disorders (sensitivity 86%, specificity 31%). Conclusion: The Axis-II Depression and Graded Chronic Pain instruments have clinically relevant and acceptable psychometric properties for reliability and validity and utility as instruments for identifying TMD patients with high levels of distress, pain, and disability that can interfere with treatment response and course of Axis I disorders.