Complete blood count-derived inflammatory markers following electroconvulsive therapy: a retrospective cohort study

Background Electroconvulsive therapy (ECT) is an effective treatment for severe psychiatric disorders, but changes in peripheral inflammatory markers during ECT remain incompletely understood. This study examined changes in complete blood count-derived inflammatory ratios following an ECT course in patients with schizophrenia, bipolar disorder, and major depressive disorder. Methods This retrospective cohort study included 112 inpatients treated with ECT between 2012 and 2022, comprising 41 patients with schizophrenia, 36 with bipolar I disorder experiencing a manic episode, and 35 with major depressive disorder. Fasting blood samples were obtained 48–72 h before the first ECT session and within five days after the final session. Concomitant psychotropic regimens remained unchanged during ECT. Paired comparisons were performed using Wilcoxon signed-rank or paired-samples t tests, as appropriate, with Holm correction for multiple comparisons. Baseline-adjusted ANCOVA models were used to examine diagnostic-group differences. Results Median NLR decreased from 2.58 (Q1–Q3, 2.02–4.05) to 2.25 (1.73–2.81), PLR from 121.51 (100.99–162.36) to 113.16 (96.63–137.14), and MLR from 0.245 (0.189–0.313) to 0.200 (0.156–0.242). All three reductions remained significant after Holm correction (NLR and MLR, p < .001; PLR, p = .024). White blood cell, neutrophil, and monocyte counts also decreased significantly, whereas lymphocyte count, platelet count, and CRP did not show significant changes after correction. In subgroup analyses, only the reduction in MLR in bipolar mania and NLR in major depressive disorder remained significant after Holm correction. No significant diagnostic-group effects were detected in baseline-adjusted analyses. Conclusions An ECT course was associated with reductions in peripheral inflammatory ratios across schizophrenia, bipolar disorder, and major depressive disorder. However, the absence of a non-ECT comparison group prevents attribution of these changes specifically to ECT, and nonsignificant between-group differences do not establish equivalent responses across diagnoses.