Relationship Between Obesity and Ventilator-Associated Pneumonia: A Post Hoc Analysis of the NUTRIREA2 Trial

Background: Patients with obesity are at higher risk for community-acquired and nosocomial infections. However, no study has specifically evaluated the relationship between obesity and ventilator-associated pneumonia (VAP).

Research question: Is obesity associated with an increased incidence of VAP?

Study design and methods: This study was a post hoc analysis of the Impact of Early Enteral vs Parenteral Nutrition on Mortality in Patients Requiring Mechanical Ventilation and Catecholamines (NUTRIREA2) open-label, randomized controlled trial performed in 44 French ICUs. Adults receiving invasive mechanical ventilation and vasopressor support for shock and parenteral nutrition or enteral nutrition were included. Obesity was defined as BMI ≥ 30 kg/m² at ICU admission. VAP diagnosis was adjudicated by an independent blinded committee, based on all available clinical, radiologic, and microbiologic data. Only first VAP episodes were taken into account. Incidence of VAP was analyzed by using the Fine and Gray model, with extubation and death as competing risks.

Results: A total of 699 (30%) of the 2,325 included patients had obesity; 224 first VAP episodes were diagnosed (60 and 164 in obese and nonobese groups, respectively). The incidence of VAP at day 28 was 8.6% vs 10.1% in the two groups (hazard ratio, 0.85; 95% CI 0.63-1.14; P = .26). After adjustment on sex, McCabe score, age, antiulcer treatment, and Sequential Organ Failure Assessment at randomization, the incidence of VAP remained nonsignificant between obese and nonobese patients (hazard ratio, 0.893; 95% CI, 0.66-1.2; P = .46). Although no significant difference was found in duration of mechanical ventilation and ICU length of stay, 90-day mortality was significantly lower in obese than in nonobese patients (272 of 692 [39.3%] patients vs 718 of 1,605 [44.7%]; P = .02). In a subgroup of patients (n = 123) with available pepsin and alpha-amylase measurements, no significant difference was found in rate of abundant microaspiration of gastric contents, or oropharyngeal secretions between obese and nonobese patients.

Interpretation: Our results suggest that obesity has no significant impact on the incidence of VAP.