Defining and Differentiating Treatment-Resistant Depression
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Individuals diagnosed with major depressive disorder (MDD), who are unable to achieve an adequate therapeutic response despite completing multiple antidepressant therapies, are commonly referred to as experiencing treatment-resistant depression (TRD). Despite the common occurrence and debilitating nature of TRD, currently there is no standardized and universally accepted definition for TRD. The Maudsley Staging Method (MSM) is a novel, multidimensional staging method for TRD that incorporates clinical and treatment factors. Although the multidimensional nature of the MSM makes it an ideal method for staging and identifying TRD, additional research is needed to better understand this newly developed staging method. The objective of this study was to evaluate the psychometric characteristics and clinical utility of the MSM. This involved (1) determining a reliable MSM cutoff score to differentiate TRD from non-TRD, (2) examining the extent of agreement between the MSM and another commonly used method of defining TRD, and (3) examining the construct validity of the MSM. This study also used the MSM to identify patients with TRD in order to perform a preliminary examination of the frequency of individual depressive symptoms associated with TRD. The data for this study was derived from four clinical investigations and included socio-demographic, clinical, and antidepressant treatment information for 88 patients diagnosed with MDD. This study identified an optimal cutoff score (7.5) for the MSM for differentiating TRD from non-TRD, and demonstrated moderate agreement between the MSM and another commonly used method for defining TRD. Depression symptom severity and current MDE duration had a significant, positive relationship with the MSM, which provided support for its construct validity. However, the MSM was not associated with certain demographic characteristics (e.g., female sex, older age) assumed to be related to TRD. This study provided an initial description of the frequency of individual depressive symptoms experienced by patients with TRD. Future research should further evaluate the individual subscales that comprise the MSM and the impact different prescription guideline may have on a patient’s MSM score and TRD classification. The MSM should also be evaluated outside of a research setting to determine its practical use in a clinical setting.