IMMPACT recommendations for clinical trials: opportunities for the RDC/TMD.

The Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) recommendations for core domains and measures of outcome in clinical trials complement the parallel work completed on Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The overall approach of the RDC/TMD is consistent with the IMMPACT recommendations, although the specific tools used to quantify clinical presentation are appropriately different based on the precedents established in the TMD literature. The IMMPACT recommendations, while directed at clinical trials, have broad utility for all clinical research in TMD. Future TMD studies should consider including a measure of health-related quality of life and tracking participant disposition, as well as tracking adverse events from treatment and assessing the participant's global assessment of change in clinical trials. The RDC/TMD methodology provides a rich basis upon which to develop standards for quantifying the clinical significance of treatment outcomes across multiple domains, an area ripe for development. Axis II may benefit from a shift in conceptualisation in which measurement focuses on screening for depression and somatisation to a new, dimensional approach in which Axis II domains are measured and evaluated on a continuum of symptom severity. Combined with the expansion of Axis II to include measures of catastrophising and sleep disturbance, the resulting approach may provide a powerful method for evaluating risk profiles associated with poor outcomes in TMD.