Impact of bariatric surgery on the risk of hospitalization due to influenza virus infection.

Background: Obesity independently increases the risk of hospitalization due to viral respiratory infections, including influenza virus and, more recently, severe acute respiratory syndrome coronavirus 2. As an independent risk factor, obesity impairs the immune response to viral infections and decreases the effectiveness of immunizations.

Objectives: Using influenza as a proxy, we aimed to determine the impact of bariatric surgery (BaS) on the risk of hospitalization due to viral respiratory infections.

Setting: Academic hospital, United States.

Methods: National (Nationwide) Inpatient Sample data collected from 2010 to 2015 were examined. Patients were classified as treatment and control groups. Treatment subjects were defined as patients with a history of BaS and control subjects as patients with a body mass index ≥35 kg/m and without a history of BaS. Any hospitalization with influenza as a primary diagnosis was identified. Univariate analysis and multivariate regression models were performed to assess the differences between groups.

Results: A total of 2,300,845 subjects were reviewed, of which 2,004,804 were control subjects and 296,041 were treated patients. Univariate analysis showed that the hospitalization rate in the treatment group was significantly lower than in the control group (.007% versus .019%, P < .0001), which was confirmed after adjusting for covariables (control versus treatment: odds ratio = 2.21, P = .0010).

Conclusions: BaS may decrease the risk of hospitalization due to influenza, but further prospective studies are needed to confirm these results. We also suggest that these results should be translated into the development of similar studies to determine the impact of BaS on the incidence and severity of the coronavirus disease 2019.