Evaluating a dimensional approach to treatment resistance in anxiety disorders: A two-year follow-up study

Background: Treatment resistance in anxiety disorders (TR-AD) has been previously defined by failed priortreatments and by various clinical aspects, but the impact of these aspects on course duringsubsequent treatments was never studied. Moreover, TR-AD was never studied using a dimensionalapproach. This study validated aspects of TR-AD and examined whether a TR-AD score was relatedto two-year course during treatment. Method: From the NESDA cohort, anxiety disorder patients who subsequently received treatment wereselected (n=679). Literature-derived aspects of TR-AD at baseline included anxiety severity, functionalimpairments, psychiatric comorbidity, duration, and previous treatments. These were combined into adimensional TR-AD score. Individual aspects of TR-AD and the TR-AD score were linked to anxietydisorder persistence at two-year follow-up using logistic regression analyses. Predictive properties forthe TR-AD score were assessed. Results: Current symptom severity, psychiatric comorbidity, functional impairments and previous duration ofsymptoms were closely associated with two-year anxiety disorder persistence, while treatment historywas not. The TR-AD score (10.8±2.3, range 2-23) was linked to two-year persistence (OR per pointincrement 1.29, p<0.01). The predictive properties of the TR-AD score appeared modest (AUC=0.66). Limitations: In the current study, treatment history and ongoing treatments were retrospectively assessed. It wasnot evaluated whether prior treatments failed or succeeded. Conclusions: The results in the current study suggest that when assessing TR-AD and designing a treatment plan,evaluations of treatment history should be accompanied with assessments of clinical characteristics.The dimensional TR-AD measurement presented here could be used for this purpose.