Association of Weight Loss Achieved Through Metabolic Surgery With Risk and Severity of COVID-19 Infection

Abstract

Importance: Obesity is an established risk factor for severe COVID-19 infection. However, it is not known whether losing weight is associated with reduced adverse outcomes of COVID-19 infection.

Objective: To investigate the association between a successful weight loss intervention and improved risk and severity of COVID-19 infection in patients with obesity.

Design, setting, and participants: This cohort study involved adult patients with a body mass index of 35 or higher (calculated as weight in kilograms divided by height in meters squared) who underwent weight loss surgery between January 1, 2004, and December 31, 2017, at the Cleveland Clinic Health System (CCHS). Patients in the surgical group were matched 1:3 to patients who did not have surgical intervention for their obesity (control group). The source of data was the CCHS electronic health record. Follow-up was conducted through March 1, 2021.

Exposures: Weight loss surgery including Roux-en-Y gastric bypass and sleeve gastrectomy.

Main outcomes and measures: Distinct outcomes were examined before and after COVID-19 outbreak on March 1, 2020. Weight loss and all-cause mortality were assessed between the enrollment date and March 1, 2020. Four COVID-19-related outcomes were analyzed in patients with COVID-19 diagnosis between March 1, 2020, and March 1, 2021: positive SARS-CoV-2 test result, hospitalization, need for supplemental oxygen, and severe COVID-19 infection (a composite of intensive care unit admission, need for mechanical ventilation, or death).

Results: A total of 20 212 patients (median [IQR] age, 46 [35-57] years; 77.6% female individuals [15 690]) with a median (IQR) body mass index of 45 (41-51) were enrolled. The overall median (IQR) follow-up duration was 6.1 (3.8-9.0) years. Before the COVID-19 outbreak, patients in the surgical group compared with control patients lost more weight (mean difference at 10 years from baseline: 18.6 [95% CI, 18.4-18.7] percentage points; P < .001) and had a 53% lower 10-year cumulative incidence of all-cause non-COVID-19 mortality (4.7% [95% CI, 3.7%-5.7%] vs 9.4% [95% CI, 8.7%-10.1%]; P < .001). Of the 20 212 enrolled patients, 11 809 were available on March 1, 2020, for an assessment of COVID-19-related outcomes. The rates of positive SARS-CoV-2 test results were comparable in the surgical and control groups (9.1% [95% CI, 7.9%-10.3%] vs 8.7% [95% CI, 8.0%-9.3%]; P = .71). However, undergoing weight loss surgery was associated with a lower risk of hospitalization (adjusted hazard ratio [HR], 0.51; 95% CI, 0.35-0.76; P < .001), need for supplemental oxygen (adjusted HR, 0.37; 95% CI, 0.23-0.61; P < .001), and severe COVID-19 infection (adjusted HR, 0.40; 95% CI, 0.18-0.86; P = .02).

Conclusions and relevance: This cohort study found that, among patients with obesity, substantial weight loss achieved with surgery was associated with improved outcomes of COVID-19 infection. The findings suggest that obesity can be a modifiable risk factor for the severity of COVID-19 infection.

Figure 1.. Weight Loss and Survival Data of Patients Over 10 Years of Follow-up Before the COVID-19 Outbreak

A, The mean differences in total weight loss at 10 years (censored on March 1, 2020) between surgical and control groups were estimated from a flexible regression model with a 4-knot spline on time since the index date interacted with the treatment group. B, Hazard ratios (HRs) (95% CIs) and P values were from fully adjusted Cox proportional hazards regression model that compared the relative risk of all-cause mortality in surgical vs control group (censored on March 1, 2020). All baseline variables in Table 1 were included to adjust for potential confounding.

Figure 2.. Cumulative Incidence Estimates for 4 COVID-19–Related Outcomes

Kaplan-Meier estimates of 4 prespecified COVID-19–related outcomes involved 11 809 patients between March 1, 2020, and March 1, 2021. Hazard ratios (HRs) (95% CIs) and P values were from fully adjusted Cox proportional hazards regression models that compared the relative instantaneous risk of each outcome in surgical vs control group. All baseline variables in Table 1 were included to adjust for potential confounding.

Figure 3.. Sensitivity Analysis

The surgical index dates were randomly assigned (5 times) to patients in the control group, and 5 data sets were created with the matching ratio of 1:3. The fully adjusted Cox proportional hazards regression models were run on each of the 4 COVID-19–related outcomes, and the hazard ratios (HRs) and 95% CIs for the treatment variable were obtained for each outcome in 5 data sets. Control group 1 represents the primary group who did not undergo surgery and whose data were reported in the article. The consistency of results in the sensitivity analysis supports the robustness of the findings.