# Prior Bariatric Surgery Predicts Lower Life-Threatening Morbidity in Patients Admitted for Acute Allergic Reaction and Anaphylaxis: a Propensity Score-Matched Analysis of the U.S. Nationwide Inpatient Sample, 2005–2018

## TL;DR

Bariatric surgery is linked to fewer severe complications in patients hospitalized for acute allergic reactions and anaphylaxis.

## Contribution

This study is the first to show that prior bariatric surgery reduces life-threatening outcomes in allergic reaction hospitalizations.

## Key findings

- Patients with prior bariatric surgery had lower rates of life-threatening complications like respiratory failure and sepsis.
- Bariatric surgery was associated with shorter hospital stays and better discharge outcomes.
- The study used a large U.S. inpatient database and propensity score matching to compare outcomes.

## Abstract

Acute allergic reactions may occur in susceptible individuals following exposure to various allergens. Obesity is linked to allergic reactions, and weight loss from bariatric surgery may attenuate the severity of certain conditions such as airway hyperresponsiveness in asthma. This retrospective observational study investigates associations between prior bariatric surgery and lower risk for life-threatening conditions in patients hospitalized with acute allergic reactions and anaphylaxis.

Adults ≥ 18 years old diagnosed with morbid obesity and admitted to US hospitals with acute allergic reactions/anaphylaxis were included. All data were extracted from the US Nationwide Inpatient Sample (NIS) database 2005–2018. Patients without information on in-hospital mortality, discharge destination, hospital costs, and length of stay (LOS) were excluded. Patients were divided into two groups based on prior bariatric surgery or not. All diagnoses were verified through ICD-9 and ICD-10 codes. Between-group differences and associations between variables were evaluated using logistic regression analysis.

After matching, patients with prior bariatric surgery had significantly lower proportions of any life-threatening morbidity (37.2% vs. 47.4%), respiratory distress or failure (11.2% vs. 17.0%), pneumonia or severe infection (7.4% vs. 10.2%), sepsis/septic shock (15.2% vs. 20.9%), intubation and mechanical ventilation (11.2% vs. 14.6%), prolonged LOS (10.3% vs. 20.6%) and unfavorable discharge (6.9% vs. 12.5%) than those without prior bariatric surgery.

Prior bariatric surgery predicts a lower risk of life-threatening morbidity and prolonged LOS among adults hospitalized for acute allergic reaction and anaphylaxis. Future prospective studies are warranted to confirm the present findings and reveal underlying mechanisms.

The online version contains supplementary material available at 10.1007/s11695-024-07115-6.