肥胖是否改善社区获得性肺炎患者的预后？——来自MIMIC-IV数据库的启示​

Abstract

Objective: Positive associations between body mass index (BMI) and clinical outcomes have been found and are called “obesity paradox”. However, whether obesity has protective effects on critically ill patients with community-acquired pneumonia (CAP) remains unclear. Herein, this study aims to investigate the association of BMI with outcomes in critically ill patients with CAP.

研究目的：已有研究发现体重指数（BMI）与临床结局之间存在正相关关系，这种现象被称为“肥胖悖论”。然而，肥胖对社区获得性肺炎（CAP）危重症患者是否具有保护作用仍不明确。本研究旨在探讨BMI与CAP危重症患者临床结局之间的关系。

Methods: This cohort study analyzed patients with CAP requiring ICU admission from the Medical Information Mart for Intensive Care (MIMIC)-IV database. Patients were categorized as underweight, normal weight, overweight and obese group. Study outcomes included 90-day mortality, sepsis development, acute kidney injury (AKI) occurrence, length of hospital stay (LOS), length of ICU stay and mechanical ventilation. Multivariate regression models and restricted cubic spline (RCS) regression were performed to analyze the impact of BMI on study outcomes adjusting for possible confounding variables.

研究方法：本研究为队列研究，分析了来自重症监护医疗信息数据库（MIMIC-IV）中需要入住重症监护病房（ICU）的CAP患者。根据BMI将患者分为体重过低组、正常体重组、超重组和肥胖组。研究结局包括90天死亡率、脓毒症发生情况、急性肾损伤（AKI）发生率、住院时长（LOS）、ICU住院时长以及机械通气使用情况。通过多变量回归模型和限制性立方样条（RCS）回归分析，在调整可能的混杂因素后评估BMI对各研究结局的影响。

Results: A total of 2874 eligible patients were enrolled in this study. The study population had a median age of 67.0 years with a male predominance (54.9 %). The underweight group had the highest mortality rate, while the obese group exhibited lowest rates. Obese was significantly associated with a longer length of ICU stay, duration of ventilation, and an increased risk of AKI. RCS analysis further confirmed a L-shaped relationship between BMI and 90-day mortality, with the lowest mortality risk observed at a BMI range of 33-35 kg/m². The incremental benefit of increasing BMI plateaued at 34 kg/m².

研究结果：共纳入2874名符合标准的患者。研究人群的中位年龄为67.0岁，男性占多数（54.9%）。体重过低组的死亡率最高，而肥胖组的死亡率最低。肥胖与更长的ICU住院时间、更长的机械通气时间以及更高的急性肾损伤风险显著相关。RCS分析进一步证实，BMI与90天死亡率呈L型关系，BMI在33–35 kg/m²范围内时死亡率风险最低。当BMI超过34 kg/m²后，增加BMI带来的额外生存获益趋于平缓。

Conclusions: A relationship between obesity and mortality was identified in critically ill patients wi1th CAP. Notably, our study uniquely reveals that the relationship between BMI and 90-day mortality is non-linear, and there is no additional mortality-reducing benefit associated with increasing BMI levels among individuals with a BMI exceeding 34 kg/m². 

研究结论：在CAP危重症患者中，我们发现了肥胖与死亡率之间存在一定关联。值得注意的是，本研究独特地揭示了BMI与90天死亡率之间呈非线性关系，并且当个体BMI超过34 kg/m²后，进一步提高BMI水平并不能带来额外的降低死亡率的益处。