Dear Editor
We read with great interest the article by Yan et al. on the clinical significance of the Systemic Immune-Inflammation Index (SII) in acute appendicitis. The authors present SII as a cost-effective biomarker, derived from platelet, neutrophil, and lymphocyte counts, which correlates with pathological severity and surgical decision-making [1]. We appreciate the study’s valuable contribution to the field, particularly its focus on health economics. In order to further enhance the clinical applicability of these findings, we would like to offer some observations and suggestions for consideration.
First, we would like to address the methodological clarity regarding confounding factors. The SII is derived from haematological parameters that are highly sensitive to external variables. Platelet and white blood cell counts can be significantly altered by prior pharmacological interventions, such as corticosteroids or antimicrobial therapy, as well as physiological states including dehydration or underlying immunosuppressive conditions [2]. However, the study’s exclusion criteria appear broad, excluding only ‘cases deemed inappropriate by the research team’. Furthermore, the category of ‘Other diseases’ represents a substantial proportion of comorbidities – 61.3% in the surgical group and 65.9% in the conservative group [1]. Clarification on whether patients with pre-admission antibiotic use or systemic haematological disorders were excluded is essential to ensure the index’s diagnostic accuracy.
Second, we turn to the validation of clinical thresholds. The authors propose preliminary thresholds for SII – SII ≥ 2500 necessitating drainage and SII ≤ 2000 not requiring it. While these thresholds provide a quantitative reference, they appear based on data distribution rather than rigorous statistical optimization. We recommend performing a Receiver Operating Characteristic (ROC) curve analysis to determine optimal cut-off values and report sensitivity, specificity, and predictive values [3]. Without such validation, implementing these thresholds could risk misdiagnosis or unnecessary interventions.
Third, comparing SII with established clinical scoring systems would further enhance its utility. Although the study briefly compares SII with procalcitonin, it lacks a direct, quantitative comparison with clinical scoring systems such as the Alvarado Score, AIR Score, and the new Adult Appendicitis Score [4]. A comparison would help demonstrate SII’s incremental value over these traditional tools, strengthening its adoption into clinical pathways.
Finally, from the perspective of China’s ‘15-minute Medical Circle’ and primary healthcare, SII holds great potential [5]. Given the resource constraints in primary care, SII offers a cost-effective ‘first line of defense’ for identifying complex cases requiring transfer to emergency medical centres. We recommend integrating SII into decision-support tools for general practitioners in community health centres to improve triage and management. Additionally, utilizing modern information technology to establish a unified data-sharing platform could enable real-time analysis of SII across different levels of care, optimizing resource allocation and reducing misdiagnosis.
In conclusion, while SII is a promising tool for managing acute appendicitis, its clinical application requires more stringent control of confounding variables and rigorous threshold validation. We thank the authors for their contribution to this field. Our suggestions are intended to help make an already excellent paper even better, and we hope that the observations provided will be considered for further enhancement of the study.
Acknowledgements
Re: Yan L, Chen Z, Xiao X, et al. Clinical significance of the systemic immune-inflammation index in relation to pathology, treatment and outcomes in acute appendicitis: a retrospective study. Ann Med. 2025;57(1):2585543.
Funding Statement
The authors reported there is no funding associated with the work featured in this article.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data availability statement
No datasets were generated or analysed in this study.
References
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Data Availability Statement
No datasets were generated or analysed in this study.