# A Case Series Analysis of Hospital Volume in a New Era of US Bariatric Surgery within the Nationwide Readmissions Database

## TL;DR

This study finds that lower-volume hospitals performing bariatric surgery have higher readmission and complication rates, even after adjusting for patient risk factors.

## Contribution

The study provides new evidence linking hospital volume to bariatric surgery outcomes using a national database from 2016 to 2022.

## Key findings

- Lower-volume hospitals had higher readmission and morbidity rates after bariatric surgery.
- Hospital volume significantly influenced length of stay, with low-volume centers showing the highest increase.
- Adjusting for patient risk still showed increased adverse events at lower-volume centers.

## Abstract

Bariatric surgery is an effective treatment for class III obesity, and higher hospital volume is associated with improved outcomes. We examined readmission, morbidity, and length of stay (LOS) by bariatric center volume in the Nationwide Readmissions Database (NRD).

The NRD from 2016 to 2022 was used to identify VSG and RYGB procedures with each hospital stratified by very low (1–24), low (25–49), medium (50–124), and high (≥ 125) annual case volume. Univariate tests assessed differences for each volume stratum. 90-day readmission and morbidity were modeled using multivariable logistic regression; LOS was analyzed with a random intercepts model for unique hospitals.

Overall, 4.6%, 6.9%, 31.1%, and 57.6% of patients underwent surgery at very low, low, medium, and high volume centers. Patients at lower volume centers had lower socioeconomic status and higher risk profiles. Readmission and morbidity rates were 15.4%, 6.9%, 4.1%, and 3.2% and 26.0%, 13.2%, 11.9%, and 10.9%, respectively for each volume designation. Very low volume centers showed the highest risk, with low and medium volumes also significantly associated with increased readmission and morbidity. For LOS, low volume had the highest estimated increase of all predictors with medium volume centers also predicting increased LOS. Individual hospitals represented a significant source of variation for total LOS.

Although patients who had surgery at lower volume centers had higher risk profiles, after adjustment there is evidence that lower volume centers are more often associated with increased adverse events. Healthcare teams, accreditation centers, and insurance providers should strive to design and follow patterns of care associated with lower risk.

The online version contains supplementary material available at 10.1007/s11695-025-08300-x.