ORIGINAL RESEARCH article
Front. Immunol.
Sec. Inflammation
Volume 16 - 2025 | doi: 10.3389/fimmu.2025.1624655
Frailty Index-laboratory and Lymphocyte Subset Patterns in Predicting 28-day Mortality Among Elderly Sepsis Patients: A Multicenter Observational Cohort Study
Provisionally accepted
Dongkai Li1
Na Cui2*Jiatong Hou3Zhan Shi4Xiao Li5Jiahui Zhang1Guoyu Zhao1
Xianli Lei1
Yawen Xie1
Yuefu Wang3
Hao Wang5
Zhigang Chang4- 1Department of Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China
- 2Department of Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
- 3Department of Surgical Critical Care Medicine, Shijitan Hospital, Beijing, China
- 4Department of Critical Care Medicine, Beijing Hospital, Beijing, China
- 5Department of Intensive Care Unit, Beijing Jishuitan Hospital, Capital Medical University, Beijing, China
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Background: Frailty is associated with poor outcomes in elderly sepsis patients. This study investigated the relationship between Frailty Index-laboratory (FI-lab) and lymphocyte patterns in predicting 28-day mortality among elderly sepsis patients.We conducted a multicenter prospective observational study in four tertiary hospitals in Beijing, China. FI-lab was calculated using 24 laboratory parameters.Peripheral blood lymphocyte subsets were measured at ICU admission. Lymphocyte count trajectories were classified into four phenotypes based on patterns during the first 72 hours. The primary outcome was 28-day mortality.Results: Among 1,197 patients (mean age 74.6±7.4 years), those with high FI-lab risk showed higher mortality (22.2%) than intermediate (12.0%) and low-risk groups (6.1%).Age-stratified analysis demonstrated consistent FI-lab prognostic value in both 65-79 years (OR 2.18) and ≥80 years (OR 2.47) groups. All lymphocyte subset counts were lower in non-survivors, particularly natural killer cells. In multivariable analysis, high FIlab risk (OR 2.31), APACHE-II scores (OR 1.08), heart rate (OR 1.01), NK cell count (OR 0.994), and pulmonary infection (OR 1.96) independently predicted 28-day mortality. A combined model incorporating these variables showed superior discriminative ability (AUC=0.788) with excellent internal validation (optimism-corrected AUC=0.775).compared to single predictors.Conclusions: FI-lab independently predicts mortality in elderly sepsis patients and correlates with lymphocyte abnormalities. When comprehensive immune assessment is unavailable, lymphocyte trajectory patterns offer a practical approach for risk stratification.
Keywords: Frailty, Sepsis, Elderly, Natural Killer cells, Lymphocytes
Received: 07 May 2025; Accepted: 24 Jun 2025.
Copyright: © 2025 Li, Cui, Hou, Shi, Li, Zhang, Zhao, Lei, Xie, Wang, Wang and Chang. 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) or licensor 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: Na Cui, Department of Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
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