Impact of obesity on patients with ventilator-associated pneumonia: the paradox continues

Abstract

PURPOSE: Ventilator associated pneumonia (VAP) is one of the leadings causes of mortality in patients with critical care illness. Since obesity is highly prevalent, we wanted to study its impact on the outcomes of patients who develop VAP. METHODS: Using the National Inpatient Sample (NIS) Database from 2017 to 2020, a retrospective study of adult patients with principal diagnosis of VAP with secondary diagnosis with or without obesity according to ICD-10 codes. Several comorbidities and demographics, including age, race, and gender, were analyzed. The primary endpoint was mortality, while the secondary endpoints included tracheostomy, and length of stay in days. Multivariate logistic regression model analysis was used to adjust for confounders, with a p value less than 0.05 considered statically significant. Odds ratio was adjusted for patients' demographics and comorbidities. RESULTS: The study included 4,329 patients with VAP, 497 of which had obesity. Further subclassification of the obesity group according to BMI is as follows: BMI 30-40 (151 (3.5%), BMI 40-50 (143 (3.3%), BMI above 50 (95 (2.2), and without BMI classification (108 (2.5%). The Mean age in both groups was around 58 years, 66% were females in the group with obesity compared to 40% in the control group. Caucasian white was the most common race in both groups (56% vs. 47%). Statistically significant comorbidities noticed in the obesity group included Charlson Comorbidity Index score 3 and above (55% vs. 42%), Diabetes Mellitus (57% vs. 36%), Hypertension (77% vs. 56%), chronic kidney disease (22% vs. 14%), and supraventricular tachycardia (27% vs. 19%). Rates and odds of mortality were not significantly higher in the collective obesity group (45 (9%) vs. 330 (8.6%), p value <0.89, aOR 1.16, p value 0.71). Similar results were seen in the BMI subgroup analysis. Although the rate of tracheostomy was higher in the obesity group (5 (1%) vs. 10 (0.26%), this was not statistically significant, neither was the adjusted odds ratio (aOR 3.9, p value 0.29). In the BMI subgroup analysis, patients with a BMI between 30-40 had higher rates and odds of tracheostomy (5 (3%) vs. 8 (0.2%), p value <0.01, aOR 12.3, p value 0.06). Length of stay (LOS) in days was 11.18 vs 11.3 in the group with and without obesity respectively, the adjusted means was -0.17 days, p value 0.89. In the subgroup analysis, paradoxical results for LOS were seen. Patients in the BMI group 30-40 had a shorted LOS (8 vs. 11.43, adjusted means –3.2 days, p value <0.01) while patients in the BMI 40-50 group when compared to non-obese patients had a longer stay (17.9 vs. 11 days, adjusted means +6.4 days, p value 0.04). CONCLUSIONS: Obesity was not found to be an independent risk factor of worse outcomes in patients who develop VAP in the intensive care unit. CLINICAL IMPLICATIONS: Obesity continues to present itself as a paradox when it comes to its impact on patients with critical care illness, in this study, clinicians should know that obesity didn't have an impact on mortality but was associated with higher tracheostomy rates.