Patients with obesity who had substantial weight loss following metabolic surgery had improved outcomes if they subsequently contracted COVID-19 infection compared with those who did not have surgery. The results were published in JAMA Surgery.

The retrospective, observational study was based on data from electronic health records of the Cleveland Clinic Health System (CCHS). Eligible patients were aged 18 to 80 years with a body mass index (BMI) between 35 and 80 who had either Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) between January 1, 2004, and December 31, 2017. Patients in the surgical group were matched 1:3 with people with obesity who did not have weight loss surgery.

Weight loss and all-cause mortality groups were compared with the surgical and control groups from the study enrollment date through March 1, 2020. Study outcomes were assessed before and after the COVID-19 pandemic began.


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A total of 20,212 patients (77.6% women; 73.8% White) were enrolled, including 5053 who had weight loss surgery. The group had 3348 [66.3%] people who had RYGB and 1705 [33.7%] who had SG. The rest of the enrollees (15,159) did not have metabolic surgery. Participants had a median (interquartile range [IQR]) age of 46 (35-57) years and a median (IQR) BMI of 45 (41-51).

At 10 years (before the COVID-19 pandemic) the mean total weight loss was 20.8 (95% CI, 20.6-21.0) percentage points of body weight in the metabolic surgery group, and 2.3 (95% CI, 2.1-2.5) percentage points of body weight in the control group. The mean difference between the two group was 18.6 (95% CI, 18.4-18.7) percentage points of body weight (P < .001).

The surgical group had a cumulative incidence of all-cause mortality at 10 years of 4.7% (95% CI, 3.7%-5.7%) compared with 9.4% (95% CI, 8.7%-10.1%) in the control group, for an adjusted hazard ratio (HR) of 0.47 (95% CI, 0.38-0.57; P < .001).

In the at-risk cohort after the COVID-19 outbreak, 11,809 patients (including 2958 patients [25.0%] in the surgical group and 8851 patients [75.0%] in the control group) were accessed on March 1, 2020 for COVID-19–related outcomes for a 12-month period.

A total of 206 patients in the surgical weight loss group and 578 patients in the control group tested positive for COVID-19 between March 1, 2020, and March 1, 2021. The cumulative incidence of COVID-19 infection was 9.1% (95% CI, 7.9%-10.3%) in the surgical group, and 8.7% (95% CI, 8.0%-9.3%) in the control group,  with an adjusted HR of 1.03 (95% CI, 0.87-1.22; P = .71).

Weight loss surgery was associated with a 49% lower risk of hospitalization (adjusted HR, 0.51; 95% CI, 0.35-0.76; P < .001) for the patients who subsequently contracted the COVID-19 infection, a 63% lower risk of the need for supplemental oxygen (adjusted HR, 0.37; 95% CI, 0.23-0.61; P < .001), and 60% lower risk of severe COVID-19 infection (adjusted HR, 0.40; 95% CI, 0.18- 0.86; P = .02).

Among several study limitations, the investigators noted that residual measured or unmeasured confounders could have potentially altered the findings (in part due to COVID-19 being a new disease), and a relatively small number of events leading to wide confidence intervals for the outcomes. In addition, the study was not designed to identify the underlying mechanisms associated with the favorable outcomes in the surgical group.

“The findings of this study suggest that obesity can be a modifiable risk factor for the severity of COVID-19 infection,” the researchers concluded.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Additionally, the study was funded by a grant from Medtronic, a medical device company. Please see the original reference for a full list of authors’ disclosures.

Reference

Aminian A, Tu C, Milinovich A, et al. Association of weight loss achieved through metabolic surgery with risk and severity of COVID-19 infection. JAMA Surgery. Published online December 29, 2021. doi:10.1001/jamasurg.2021.6496