Low eosinophils and their dynamic as a predictor of death in patients with infections: a systematic review and meta-analysis of cohort studies

Eosinophils prognostic significance in predicting mortality has become particularly notable during the COVID-19 pandemic. We aimed to evaluate the prognostic value of peripheral low eosinophil (eosinopenia) with focus on their dynamics (eosinophil recovery) in patients with infections. We searched databases (MEDLINE, Embase, Scopus, Web of Science, and the Cochrane Library) and additional sources from inception to 1 December 2023. Cohort studies involving adult patients hospitalized with infections were evaluated using dual-reviewer methodology. Out of 15,066 screened papers, 151 studies met the inclusion criteria, with 107 focused on COVID-19, 14 on sepsis, 9 on Clostridioides difficile, 6 on acute COPD exacerbations, and 17 on other infections. The majority of studies reported significantly lower admission eosinophil levels in non-survivors compared to survivors. Random-effects model meta-analysis showed mean eosinophil difference between deceased and survivors −15.31 (95% CI: −18.72 to −11.90) for COVID-19 and −44.6 (95% CI: −95.62 to 6.41) for sepsis (I2 > 90%). Mortality with eosinopenia showed low certainty of evidence for C. difficile (0 cells/mm³ cut-off: RR 2.35; 95% CI: 1.84–2.99) and very low for COVID-19 when considering different cut-offs (0 cells/mm³: RR 2.37; 95% CI: 1.86–3.01; 20 cells/mm³: RR 2.90; 95% CI: 1.59–5.28; 50 cells/mm³: RR 2.70; 95% CI: 1.33–5.49). Survivors generally showed an increase in eosinophil counts within the first 2–5 days of hospitalization, while the deceased had persistently low levels. Eosinopenia, particularly the trajectory of eosinophil recovery, may serve as a cost-effective and accessible prognostic marker for mortality in patients with infections.

嗜酸性粒细胞（Eosinophils）预测死亡的预后意义，在COVID-19大流行期间尤为凸显。本研究旨在评估外周血嗜酸性粒细胞减少（eosinopenia）的预后价值，并重点关注感染患者体内嗜酸性粒细胞的动态变化（嗜酸性粒细胞恢复情况）。本研究检索了自建库至2023年12月1日的MEDLINE、Embase、Scopus、Web of Science及Cochrane Library数据库及其他相关文献来源。本研究采用双人审稿法，对纳入的成年住院感染患者队列研究进行筛选评估。在15066篇经筛选的文献中，共151项研究符合纳入标准：其中107项聚焦COVID-19，14项针对脓毒症（sepsis），9项针对艰难梭菌（Clostridioides difficile）感染，6项针对慢性阻塞性肺疾病急性加重（acute COPD exacerbations），另有17项针对其他感染性疾病。多数研究结果显示，与存活患者相比，非存活患者入院时的嗜酸性粒细胞水平显著更低。随机效应模型（random-effects model）的荟萃分析（meta-analysis）结果显示，COVID-19患者的死亡者与存活者嗜酸性粒细胞平均差值为−15.31（95%置信区间（Confidence Interval, CI）：−18.72至−11.90），脓毒症患者则为−44.6（95%CI：−95.62至6.41）（I²>90%）。针对嗜酸性粒细胞减少症与死亡风险的关联，艰难梭菌感染的证据确定性等级为低（截断值（cut-off）0个/mm³：相对危险度（Relative Risk, RR）2.35；95%CI：1.84至2.99）；而当采用不同截断值分析COVID-19时，证据确定性等级则为极低（0个/mm³：RR 2.37，95%CI：1.86至3.01；20个/mm³：RR 2.90，95%CI：1.59至5.28；50个/mm³：RR 2.70，95%CI：1.33至5.49）。存活患者通常在入院后2至5天内嗜酸性粒细胞计数出现回升，而非存活患者则持续维持低水平。嗜酸性粒细胞减少症，尤其是嗜酸性粒细胞恢复的动态轨迹，可作为感染患者死亡风险的一项经济便捷且易于获取的预后标志物。