Prior bariatric surgery in COVID positive patients may offer protection against severity of illness

Patients who has bariatric surgery before they tested positive for CVOID-19 were less likely to be admitted to hospital, had a shorter stay in intensive care units ICUs), less likely to require a ventilator during the admission and less likely to die, compared with a control cohort of COVID-19 positive patients who were eligible for bariatric surgery (BMI >40kg/m2 or BMI >35kg/m2 with a comorbidity at the time of COVID-19 diagnosis). The findings were featured in the paper, ‘Prior Bariatric Surgery in COVID-19 Positive Patients May Be Protective', published in the journal Surgery for Obesity and Related Diseases (SOARD), the Official Journal of the American Society for Metabolic and Bariatric Surgery (ASMBS) and the Brazilian Society for Bariatric Surgery.

The paper’s authors from NYU Langone Health, New York, NY, noted that previous studies have revealed that age, gender and obesity are strongly correlated with poor outcomes in COVID-19 positive patients. Moreover, Bariatric surgery is the only long-term treatment that provides significant, sustained weight loss in patients living with severe obesity. Therefore, the researchers designed a study to investigate any potential correlation between history of bariatric surgery and improved outcomes in patients diagnosed with COVID-19.


Using data from their centre, the researchers created two groups:

  • Patients who had prior bariatric surgery and subsequently tested positive for COVID-19 (n=124); and

  • A control group, who had body mass index (BMI) >40 kg/m2 OR BMI >35 kg/m2 with a comorbidity (diabetes, hypertension, or hyperlipidaemia) present at the time of COVID-19 diagnosis (n=496 controls)

The surgical group included three types of bariatric procedures: Roux-en-Y Gastric Bypass (RYGB, n=45 36%), laparoscopic adjustable gastric banding (LAGB, n=44, 35%) and laparoscopic sleeve gastrectomy (LSG, n=35, 28%).


The average age in the surgical group was 51.7 years (SD = 12.6) and 52.1 years (SD=12.9) in the control group. In both groups 69% of patients were female and there was no statistical differences between these groups. There was no statistical difference in the racial demographics, the week of admission, the distribution of the burden of hypertension, hyperlipidaemia, initial inflammatory marker values (CRP and D-dimer), history of myocardial infarction (MI), or history of stroke between the bariatric and control groups. However, BMI in the bariatric group was 36.1 kg/m2 (SD=8.3), significantly lower than the control group, 41.4 kg/m2 (SD=6.5) (p<0.0001) and there was also less burden of diabetes in the bariatric group (32%) vs the control group (48%) (p=0.0019).

The researchers then carried out Chi-square tests to determine if there was a comparable difference in the frequency of outcomes between the bariatric and control groups. The following values were confirmed using an unadjusted conditional logistic regression model:

  • Patients in the surgical group were less likely to be admitted through the emergency room (p=0.0001), compared to the control group

  • · Patients in the surgical group were less likely to have had a ventilator used during the admission (p=0.028), compared to the control group

  • The control group patients also had a longer length of stay in the ICU (p=0.033), vs the surgical group

  • Total length of stay greater than one day was less in the bariatric group as well (p=0.0002), although ICU admission was lower in the bariatric surgery group, this was not significant; and

  • Patients in the surgical group were less likely to be deceased at discharge compared to the control group (p=0.028).

When the analysis was conducted adjusting for BMI, race/ethnicity, diabetes, hypertension, hyperlipidaemia, history of MI and history of stroke, patients in the surgical group were still less likely to be admitted from the emergency department (p=0.015), although the remaining outcomes were no longer significant.

“As the United States has become an epicenter of COVID-19, these findings are even more important, since over 40% of the American population has obesity,” the authors write. “In conclusion, our results emphasise the importance of bariatric surgery as a protective factor against severe COVID-19 infection and death in the high-risk population with obesity and independently decreases the risk of hospitalisation.”

Further information

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