T028 Efficacy is not equal to effectiveness: Transcranial magnetic stimulation in the treatment of depressive disorder

Abstract

Administering transcranial magnetic stimulation to the prefrontal cortex is efficacious for the management of depressive symptoms. Data demonstrating efficacy are often assumed to be similar to effectiveness data, but this assumption is not correct. Efficacy is the extent to which a treatment does more good than harm under experimentally controlled conditions, whereas effectiveness is the extent to which a treatment does more good than harm when provided under the usual conditions of health care practice. Efficacy studies often overestimate the effect of treatment when implemented in clinical practice effectiveness research accounts for additional variability, including patient characteristics and suboptimal TMS dosage, that moderate treatment effect (Eichler et al., 2011). While the main clinical outcome measure in TMS efficacy studies is the baseline adjusted change score on established clinical ratings scales, assessment of health outcomes including quality adjusted life years has not been extensively studied. In fact, cost-utility analyses are critical to establish external validity by showing that the efficacy in randomized controlled trials reflects clinical practice. Together with the absence of mechanistic neurophysiological explanations and lack of insight into the duration of the effects, the effectiveness of TMS in the treatment of depression remains an open question (Gartlehner et al., 2006). TMS improve symptoms of depression, but due to the multifactorial nature of the intervention, the overall effectiveness of TMS for the treatment of depression remains unclear (Canadian Agency for Drugs and Technologies in Health, 2014). Effectiveness studies are needed in order to consider TMS a realistic option for health-care decisions by practitioners and policy-makers in the treatment of depressive disorder.