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. 2026 Feb 26.
doi: 10.1186/s40001-026-04108-2. Online ahead of print.

Threshold effects of baseline BMI on 30-day hospital mortality in critically Ill COPD patients: a multicenter retrospective study

Pan Zhou #  1 , Xin Li #  1 , Zhe Deng  2
Affiliations
Free article

Threshold effects of baseline BMI on 30-day hospital mortality in critically Ill COPD patients: a multicenter retrospective study

Pan Zhou et al. Eur J Med Res. .
Free article

Abstract

Objective: Despite well-documented obesity paradoxes in critical illness, the precise relationship between body mass index (BMI) and mortality in critically ill chronic obstructive pulmonary disease (COPD) patients remains unclear. This study aimed to identify potential BMI thresholds associated with survival outcomes in this high-risk population.

Methods: This retrospective multicenter cohort study analyzed 10,179 critically ill COPD patients from 208 U.S. hospitals in the eICU Collaborative Research Database (2014-2015). The exposure variable was BMI measured within 24 h of intensive care unit (ICU) admission. The primary outcome was in-hospital mortality. Covariates included demographics, laboratory parameters, disease severity scores, comorbidities, and treatments. Restricted cubic splines and two-piecewise linear regression models were used to identify non-linear BMI-mortality associations, with subgroup analyses stratified by 13 clinical variables.

Results: Among 10,179 patients (mean age 67.9 years; 50.0% male), overall ICU mortality was 5.6%. A BMI threshold of 20.8 kg/m2 (95%CI 20.5-21.2) was identified. Below this threshold, each 1 kg/m2 BMI increase was associated with 13% lower mortality risk (OR = 0.87, 95%CI 0.80-0.93, P < 0.001). Above 20.8 kg/m2, no association was observed (OR = 0.99, 95%CI 0.98-1.01, P = 0.372). This threshold-dependent pattern remained consistent across all subgroups (all P for interaction > 0.05).

Conclusion: This retrospective analysis identified a BMI threshold of 20.8 kg/m2 associated with differential ICU mortality risk in critically ill COPD patients. These observational findings may inform BMI-stratified risk assessment in ICU COPD populations, though prospective validation is warranted.

Keywords: Body mass index; Chronic obstructive pulmonary disease; Critical care; Intensive care units; Obesity paradox.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: This study utilized de-identified data from the eICU Collaborative Research Database (eICU-CRD v2.0). The original data collection was approved by institutional review boards and complied with the Declaration of Helsinki. As this involved secondary analysis of de-identified data, institutional review board approval and individual patient consent were waived in accordance with 45 CFR 46.104(d)(4). Database access was obtained through PhysioNet (https://physionet.org/) following completion of required training and signing of a Data Use Agreement. Consent for publication: Not applicable. This manuscript does not contain any individual person’s identifiable data. Competing interests: The authors declare no competing interests.

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