Correlation of RDC/TMD axis I diagnoses and axis II pain-related disability. A multicenter study

As part of an ongoing multicenter investigation involving four highly specialized tertiary clinics for temporomandibular disorders (TMD) treatment, retrospective analysis of Research Diagnostic Criteria for TMD (RDC/TMD) axis I and axis II data gathered on clinic and community cases were assessed with a twofold aim: (1) to search for a correlation between axis I diagnoses and axis II pain-related disability, and (2) to identify clinical (axis I) and psychosocial (axis II) predictors of high pain-related disability. Two samples of patients seeking treatment for TMD (clinic cases, N = 1,312) and a sample of general population subjects (community cases, N = 211) underwent a thorough assessment in accordance with the RDC/TMD version 1.0 [1] guidelines to receive both axis I and axis II diagnoses. Spearman's test was performed to assess the level of correlation between axis I diagnoses and Graded Chronic Pain Scale (GCPS) pain-related disability. A stepwise multiple logistic regression model was used to identify the significant associations between 12 clinical and psychosocial predictors and the presence of high pain-related disability. Axis I findings were related with pain-related impairment (GCPS scores) in the overall study sample including both clinic community cases (Spearman correlation = 0.129, p = 0.000), but the results of the correlation analyses performed on the clinic sample alone were not significant (Spearman correlation = -0.018, p = 0.618). Predictors for high disability were related to axis II findings (severe depression and somatization) or psychosocial aspects related to the pain experience (pain lasting from more than 6 months; treatment-seeking behavior), while none of the axis I diagnoses remained in the final logistic regression model. The final model predicted the level of pain-related impairment at a fair level (R(2) = 26.7%). The correlation between axis I diagnoses and pain-related impairment is not significant in the patients populations. Treatment-seeking behavior and other factors related with the pain experience are likely to be more important than the physical findings to determine the degree of psychosocial impairment.