Table 1. Summary of cohort studies of COVID-19 patients in relation to BMI and obesity, in China, Italy, France, the United Kingdom, and the United States.

NYC: New York City; COVID-19: coronavirus disease 2019;  CVD: cardiovascular disease; VA: Veterans Affairs

Study	Patient Population	General Findings
Marcello et al., 2020 [42]	13,442 COVID-19 positive individuals (of 22,254 tested). 6,248 individuals were hospitalized, of which 1724 deceased. Patients were part of the NYC health and hospital public health system.	Overweight and obese individuals were significantly more likely to test positive and to be hospitalized. Obese hospitalized patients had a higher (but not significant) mortality rate than normal-weight patients (11% vs 8%).
Docherty et al., 2020 [43]	20,133 COVID-19 positive in-patients throughout the United Kingdom.	Obese (BMI > 30 kg/m2) in-patients had a statistically significant elevated mortality hazard ratio of 1.33, compared to normal-weight patients.
Busetto et al., 2020 [57]	92 patients in COVID-19 ward of an Italian hospital.	Overweight and obese patients were, on average, younger than normal-weight patients. Despite younger age, obese patients required more frequently assisted ventilation
Lighter et al., 2020 [50]	3,615 COVID-19 positive individuals under 60 who presented to a large academic hospital system in NYC.	775 with BMI of 30-34, and 595 with BMI>35. Obese patients under 60 were more likely to be admitted to acute and critical care.
Petrilli et al., 2020 [58]	5,279 patients hospitalized with COVID-19 in NYC	Obesity (BMI>30) was associated with an increased risk of hospital admission. The strongest risk factors predicting critical illness were age, heart failure, male sex, and BMI>40.
Cai et al., 2020 [51]	383 consecutively admitted COVID-19 patients in a hospital in Shenzhen, China	Obese patients were 3.40 times more likely to progress to severe Covid-19 requiring ICU admission
Hur et al., 2020 [52]	486 COVID-19-positive patients hospitalized across 10 hospitals in Chicago	Median BMI was 30.6. 138 total intubated patients with 78 extubated. BMI associated with increased time to extubation.
Simonnet et al., 2020 [53]	124 consecutively admitted ICU patients with COVID-19 in a French hospital	Obesity (BMI>30) seen in 75% of ICU patients. Need for invasive mechanical ventilation (IMV) significantly associated with BMI, independent of age, diabetes, and hypertension.
Peng et al., 2020 [54]	112 COVID-19 positive patients with underlying CVD in Wuhan, China	BMI of patients requiring critical care was significantly higher than non-critical care group. In addition, 88% of patients who did not survive had a BMI>25, as opposed to 19% with BMI>25 who did survive.
Eastment et al., 2020 [55]	25,952 SARS-CoV-2 positive patients from VA hospitals across the United States	Patients with a higher BMI were more likely to test positive for SARS-CoV-2. They were also more likely to need mechanical ventilation, as well as statistically more likely to die from infection. This correlation was seen in patients under 65 years of age and were attenuated or absent in patients over 65 years of age.
Goodman et al,, 2020 [56]	66,646 COVID-19 inpatients across 613 United States hospitals	Obesity, diabetes with chronic complications, and hypertension with chronic complications were risk factors in most age-groups with the highest relative risks among 20-39 year old. Male sex was also independently associated with higher mortality risk.
Gao et al., 2020 [18]	150 adult COVID-19 positive inpatients from three Chinese hospitals	The cohort was divided into 75 obese patients (BMI > 25) and 75 non-obese patients. In the obese cohort, 33.3% of patients developed severe COVID-19 pathology, compared to 14.7% of patients in the non-obese cohort. The findings were statistically significant. Median duration of hospitalization was also increased in the obese cohort.
Kass et al., 2020 [66]	A retrospective cohort of 265 COVID-19 patients admitted to the ICU at six United States academic hospital systems	There was a significant negative correlation between BMI and age among ICU admitted COVID-19 patients. Younger patients, on average, had a higher BMI than older patients. Only 25% of the COVID-19 patients admitted to the ICU had a BMI < 26.
Klang et al., 2020 [67]	3,406 COVID-19 patients admitted to a large academic hospital system in New York, United States	Cohort was subdivided into a group of patients younger than 50 years old, and one of older than 50. There was a stronger positive correlation between obesity (BMI > 40) and mortality among patients under 50, than for patients older than 50. Essentially, obesity was a strong risk factor for mortality, particularly in younger patients.