Predictors of dropout from transcranial magnetic stimulation for treatment resistant depression

Abstract: Clinical transcranial magnetic stimulation (TMS) is a well-established therapeutic intervention for treatment resistant depression and related comorbidities, yet standard TMS treatment often requires 30 daily treatments. Thus, treatment dropout could be a significant challenge for implementation. To better understand who is at risk of dropout and potentially guide future novel applications of TMS, this study examined predictors of dropout from the Veterans Affairs’ nationwide TMS program for veterans with treatment resistant depression (TRD). The sample comprised n = 1588 veterans undergoing clinical TMS treatment. We used receiver operating characteristic (ROC) analysis, which calculates the sensitivity and specificity of predictor variables at each cut-off point, to identify optimal cut-off points for the variables that significantly predicted treatment dropout. Key predictors included age and depression severity, measured by the Patient Health Questionnaire-9 (PHQ-9). Results indicated that veterans in early adulthood, specifically younger than 42 years old, were more likely to drop out, with a 22.7 % dropout rate compared to 16.3 % for those 42 and older (χ2 =9.34, p < 0.001). For veterans 42 years and older, those with severe depressive symptoms (i.e., PHQ-9 score of 24 or higher) had an increased dropout rate of 22.4 % (χ2 =4.96, p < 0.05) compared to 15.3 % among those with less severe depressive symptoms. Furthermore, we found that comorbidities did not significantly impact dropout rates. Post-hoc analyses revealed personal reasons as the most common cause for dropout, particularly among younger veterans. These findings underscore the importance of considering age and symptom severity in managing TMS treatment to improve adherence and outcomes. Future research should explore specific barriers and facilitators to treatment adherence, especially among high-risk populations.