ECT & CRP, quo vadis? - A retrospective study of low-grade inflammation in patients with depression undergoing electroconvulsive therapy

Abstract

Introduction

Electroconvulsive therapy (ECT) is the most effective treatment for severe depression. Depression has been associated with low-grade inflammation (LGI), as indicated by elevated C-reactive protein (CRP) levels compared to healthy individuals. While the effect of ECT on inflammation markers remains unclear, some evidence suggests that higher baseline CRP levels may predict remission in ECT. Additionally, LGI could influence the seizure threshold and thus the required stimulation dose.

Materials and methods

This retrospective study examined the potential link between LGI and treatment outcomes as well as stimulation doses across multiple ECT sessions, controlling for age and interparticipant variability. The hypothesis of this study was that LGI was associated with ECT remission as well as with ECT dosing in people with depression. Two groups were defined, depending on CRP levels, those with LGI (CRP 3–10 mg/L) and those without (CRP < 3 mg/L). Generalized linear models were used to analyze maximum ECT doses, while linear mixed models were applied to assess changes in ECT doses over time.

Results

After 10 ECT sessions, we found no significant difference in remission rates between patients with (n = 52) and without LGI (n = 143). However, patients with baseline LGI had higher maximum ECT doses. A linear mixed model revealed that the number of sessions and baseline LGI significantly influenced ECT doses, with patients with baseline LGI needing higher doses, particularly at the seventh session. Age also was associated with both maximum doses and dose adjustments throughout the ECT series, but the influence of LGI on ECT dose was independent of age, since no age differences were observed between groups.

Conclusions

Baseline inflammation was not associated with remission rates, but it had a significant association with ECT dosing. Therefore, while CRP may not be a reliable biomarker for predicting ECT response in depression, baseline inflammation could indicate the need for a higher stimulation dose.