We read with great interest the article by Wang et al., titled “Association between systemic immune-inflammation index and post-stroke depression: a cross-sectional study of the national health and nutrition examination survey 2005–2020,” recently published in Frontiers in Neurology (1). This article addresses a significant clinical issue by examining the relationship between the systemic immune-inflammation index (SII) and post-stroke depression (PSD).
However, after a thorough evaluation of the study design and data analysis methodologies, we would like to highlight a significant methodological concern that may potentially undermine the validity and interpretation of the results.
Specifically, participants without a history of stroke were included in the “Post-stroke depression = No” group. Post-stroke depression (PSD) is inherently a stroke sequela. Since individuals without a stroke history do not develop post-stroke depression, their inclusion may introduce non-differential misclassification, and this systematic error would attenuate the effect estimates between systemic immune-inflammation index (SII) and PSD by inflating the reference group with individuals inherently incapable of developing the outcome. This issue may explain the relatively low prevalence of PSD reported in the study, which is much lower than the 27–62% prevalence typically observed among stroke survivors, as previously reported by Zhou et al. (2).
Limiting the analysis to individuals with a confirmed history of stroke would allow for a more accurate estimation of the association between SII and PSD, thereby improving the internal validity and clinical relevance of the study results.
We thank the authors for their valuable contribution to this important area and hope that this opinion will help improve research methods in the field of stroke-related mental outcomes in the future.
Statements
Author contributions
HL: Writing – original draft. AY: Writing – review & editing.
Funding
The author(s) declare that no financial support was received for the research and/or publication of this article.
Conflict of interest
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References
1.
Wang M Peng C Jiang T Wu Q Li D Lu M . Association between systemic immune-inflammation index and post-stroke depression: a cross-sectional study of the national health and nutrition examination survey 2005–2020. Front Neurol. (2024) 15:1330338. 10.3389/fneur.2024.1330338
2.
Zhou H Zhang Y Liu Y . Research progress on post-stroke depression. Exp Neurol. (2024) 373:114660. 10.1016/j.expneurol.2023.114660
Summary
Keywords
post-stroke depression, stroke, NHANES, systemic immune-inflammation index (SII), epidemiology
Citation
Luo H and Yang A (2025) Commentary: Association between systemic immune-inflammation index and post-stroke depression: a cross-sectional study of the national health and nutrition examination survey 2005–2020. Front. Neurol. 16:1620259. doi: 10.3389/fneur.2025.1620259
Received
29 April 2025
Accepted
22 August 2025
Published
30 September 2025
Volume
16 - 2025
Edited by
Rizgar A. Mageed, Queen Mary University of London, United Kingdom
Reviewed by
Chang Liu, Second Affiliated Hospital of Chongqing Medical University, China
Updates
Copyright
© 2025 Luo and Yang.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Anqiang Yang yanganqiangke@126.com
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.