Association between pulse width and clinical response to electroconvulsive therapy

BACKGROUND: The default pulse width setting on a commonly used electroconvulsive therapy (ECT) device, 0.5 ms (ms), is untested against the proven effectiveness of conventional 1.0-1.5 ms brief pulse widths. METHODS: We examined the association between pulse width and clinical response using registry data from 87 centres in the United Kingdom and Republic of Ireland in patients (N = 1956) receiving consecutive acute courses of ECT ending during 2023 for any clinical indication. The outcome was clinical response, defined as an end-of-treatment Clinical Global Impression‒Improvement score of 1 or 2. RESULTS: Mean age was 61.6 years (SD, 16.3), 66.3 % were female, 84.2 % were treated for depressive episode, and 86.5 % received bilateral ECT. In a multivariable logistic regression analysis of all diagnostic categories, 0.5 ms (adjusted odds ratio 0.64; 95 % CI, 0.50-0.82; p < .001) and 0.25-0.3 ms (adjusted odds ratio 0.56; 95 % CI, 0.38-0.82; p = .003) pulse widths were associated with significantly lower odds of response compared to 1.0 ms. Predicted probabilities of response were 73.4 % (95 % CI, 69.4 %-77.3 %) for 1.0 ms, 64.1 % (95 % CI, 61.4 %-66.8 %) for 0.5 ms, and 61.0 % (95 % CI, 53.8 %-68.3 %) for 0.25-0.3 ms. A subgroup analysis of unipolar or bipolar depressive episodes likewise showed significantly reduced odds of response with both 0.5 ms and 0.25-0.3 ms. CONCLUSION: This study demonstrated a previously unreported association between 0.5 ms pulse width and reduced ECT response. Unless cognitive sparing is paramount in an individual case, 1.0 ms ECT should be used as standard.