Comparison of Axis II psychosocial assessment methods of RDC/TMD and DC/TMD as part of DC/TMD-FIN phase II validation studies in tertiary care Finnish TMD pain patients.

Background: The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and Diagnostic Criteria for TMD (DC/TMD) include Axis II instruments for psychosocial assessment.
Objectives: The aims were to compare the Finnish versions of Axis II psychosocial assessment methods of the RDC/TMD and DC/TMD and to study their internal reliability.
Methods: The sample comprised 197 tertiary care referral TMD pain patients. The associations between RDC/TMD [Graded Chronic Pain Scale (GCPS) 1.0, Symptom Check List 90-revised (SCL-90R)] and DC/TMD (GCPS 2.0, Patient Health Questionnaire-9 (PHQ-9), PHQ-15) assessment instruments were evaluated using Spearman correlation coefficients, Wilcoxon Signed Rank s, chi-squared test and gamma statistics. The internal reliability and internal inter-item consistency of SCL-90-R, PHQ-9, PHQ-15 and Generalized Anxiety Disorder-7 (GAD-7) were evaluated using Cronbach's alpha coefficient values.
Results: The DC/TMD and RDC/TMD Axis II psychosocial instruments correlated strongly (p < .001). GCPS 1.0 and GCPS 2.0 grades were similarly distributed based on both criteria. The RDC/TMD psychological instruments had a higher tendency to subclassify patients with more severe symptoms of depression and non-specific physical symptoms compared to DC/TMD. The internal reliability and internal inter-item consistency were high for the psychological assessment instruments.
Conclusion: The Finnish versions of the RDC/TMD and DC/TMD Axis II psychosocial instruments correlated strongly among tertiary care TMD pain patients. Furthermore, the Axis II psychological assessment instruments indicated high validity and internal inter-item consistency and are applicable in Finnish TMD pain patients as part of other comprehensive specialist level assessments, but further psychometric and cut-off evaluations are still needed.
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