Obesity paradox in sepsis: a systematic review and meta-analysis of short- and long-term mortality risks.

OBJECTIVE

To clarify the association of elevated BMI with short- and long-term mortality in sepsis, and to evaluate this association specifically in patients with a BMI ≥ 40 kg/m2.

DESIGN

Systematic review and meta-analysis.

SETTING

PubMed, Embase, and the Cochrane Library were searched for studies published up to December 2025. Twelve studies met the inclusion criteria.

PARTICIPANTS

Twelve retrospective studies with 130755 adult sepsis patients. Elevated BMI was defined as ≥30 kg/m2; normal weight as 18.5-25.0 kg/m2.

INTERVENTIONS: Not applicable.

MAIN VARIABLES OF INTEREST: Exposure: BMI ≥ 30 kg/m2.

OUTCOMES: short-term (28-day, 30-day, ICU, in-hospital) and long-term (1-year) mortality. A separate analysis targeted BMI ≥ 40 kg/m2.

RESULTS

An elevated BMI was associated with reduced short-term mortality (8 studies: OR 0.75, 95% CI 0.69-0.81; I2 = 11.8%), 28-/30-day mortality (5 studies: OR 0.74, 95% CI 0.68-0.81; I2 = 7.7%), and long-term mortality (2 studies: OR 0.68, 95% CI 0.60-0.77; I2 = 0.0%). This inverse association persisted in patients with BMI ≥ 40 kg/m2 (4 studies: OR 0.70, 95% CI 0.62-0.79; I2 = 26.3%). Sensitivity analyses confirmed robustness.

CONCLUSIONS

Elevated BMI is associated with lower short- and long-term mortality in sepsis, consistent with the obesity paradox. The inverse association also persisted in patients with a BMI ≥ 40 kg/m2.