If you come down with Covid-19, will you have a cold or end up on a ventilator? The answer is probably the former, but some people will end up with the latter. How do we predict who will get very sick? There was interest some months ago as a study done in Italy and Spain suggested that certain blood types were associated with worse outcomes. Patients call and ask for their blood type and assume that we have checked it at some point. Not true. Blood type is only checked before one gives birth or if transfusion is anticipated. People ask to know their blood type even though it isn’t something that can be changed. They just want to know. Should you check it? Save your blood.
This study aimed to determine if there is an association between ABO blood type and severity of COVID-19 defined by intubation or death as well as ascertain if there is variability in testing positive for COVID-19 between blood types. In a multi-institutional study, all adult patients who tested positive for COVID-19 across five hospitals were identified and included from March 6th to April 16th, 2020. Hospitalization, intubation, and death were evaluated for association with blood type. Univariate analysis was conducted using standard techniques and logistic regression was used to determine the independent effect of blood type on intubation and/or death and positive testing. During the study period, there were 7648 patients who received COVID-19 testing throughout the institutions. Of these, 1289 tested positive with a known blood type. A total of 484 (37.5%) were admitted to hospital, 123 (9.5%) were admitted to the ICU, 108 (8.4%) were intubated, 3 (0.2%) required ECMO, and 89 (6.9%) died. Of the 1289 patients who tested positive, 440 (34.2%) were blood type A, 201 (15.6%) were blood type B, 61 (4.7%) were blood type AB, and 587 (45.5%) were blood type O. On univariate analysis, there was no association between blood type and any of the peak inflammatory markers (peak WBC, p = 0.25; peak LDH, p = 0.40; peak ESR, p = 0.16; peak CRP, p = 0.14) nor between blood type and any of the clinical outcomes of severity (admission p = 0.20, ICU admission p = 0.94, intubation p = 0.93, proning while intubated p = 0.58, ECMO p = 0.09, and death p = 0.49). After multivariable analysis, blood type was not independently associated with risk of intubation or death (referent blood type A; blood type B: AOR: 0.72, 95% CI: 0.42–1.26, blood type AB: AOR: 0.78, CI: 0.33–1.87, blood type O: AOR: 0.77, CI: 0.51–1.16), rhesus factor positive (Rh+): AOR: 1.03, CI: 0.93–1.86. Blood type A had no correlation with positive testing (AOR: 1.00, CI: 0.88–1.13), blood type B was associated with higher odds of testing positive for disease (AOR: 1.28, CI: 1.08–1.52), AB was also associated with higher odds of testing positive (AOR: 1.37, CI: 1.02–1.83), and O was associated with a lower risk of testing positive (AOR: 0.84, CI: 0.75–0.95). Rh+ status was associated with higher odds of testing positive (AOR: 1.23, CI: 1.003–1.50). Blood type was not associated with risk of intubation or death in patients with COVID-19. Patients with blood types B and AB who received a test were more likely to test positive and blood type O was less likely to test positive. Rh+ patients were more likely to test positive.
Kaiser Study: Severe Obesity Boosts Risk of COVID-19 Death, Especially for the Young
A study in Annals of Internal Medicine shows severe obesity presents a greater risk of death from COVID-19 than related factors such as diabetes or hypertension.
Severe obesity puts those with coronavirus disease 2019 (COVID-19) at particularly high risk of death, more so than related risk factors such as diabetes or hypertension, according to a study of patient records that researchers from Kaiser Permanente published today.
The study, appearing in Annals of Internal Medicine,1 showed that obesity is especially dangerous for men and younger patients who contract COVID-19, and that obesity stood out from racial, ethnic, or socioeconomic disparities when isolated from those factors.
Data from the 6916 patients in the study show that compared with those at normal body mass index (BMI) of 18.5 to 24 kg/m2, the risk of death more than doubled for patients with a body mass index (BMI) of 40 to 44 kg/m2 (relative risk of 2.68; 95% CI, 1.43 to 5.04) and nearly doubled again for those with a BMI of 45 kg/m2 (relative risk of 4.18; 95% CI, 2.12 to 8.26).
“This risk was most striking among those aged 60 years or younger and men,” the authors wrote.
In an accompanying editorial, David A. Kass, MD, a cardiologist at John Hopkins University, wrote that these findings, when taken with prior research, “should put to rest the contention that obesity is common in severe COVID-19 because it is common in the population. Obesity is an important independent risk factor for serious COVID-19 disease.”2
Genentech funded the study.
Kaiser Permanente’s study stands out from others for a number of reasons: it gathered data not just on patients in the hospital, and authors had access to comprehensive patient data that allowed them to isolate the effect of obesity from multiple individual clinical and socioeconomic factors, including 20 different comorbidities, prior medication use, alcohol or smoking status, health care use, median household income, household education level, and the population density of the neighborhood.
Researchers even adjusted for time, because they knew that with each passing week, testing practices, social distancing, and clinical treatments changed as doctors and health officials shifted their pandemic response. The study covered patients treated from February 13 to May 2, 2020.
The authors note that they did not find a statistically significant link between Black or Hispanic race/ethnicity or neighborhood-level variables on death risk, amid “widespread concern” about the outsize share of COVID-19 deaths in minority communities. Because Kaiser Permanente is a capitated health care system, the authors speculated that patients may have greater access to care than in some parts of the United States.
Still, they noted their findings show the need to treat severe obesity as an independent risk factor and create appropriate interventions, especially in young men.
“We present findings that can inform decisions much earlier in the triage process, including in the ambulatory setting,” they wrote. “Our finding that severe obesity, particularly among younger patients, eclipses the mortality risk posed by other obesity-related conditions, such as history of myocardial infarction, diabetes, hypertension, or hyperlipidemia, suggests a significant pathophysiologic link between excess adiposity and severe COVID-19 illness.”
Kass, the Johns Hopkins cardiologist, elaborated on what might be behind these findings. “That the risks are higher in younger patients is probably not because obesity is particularly damaging in this age group; it is more likely that other serious comorbidities that evolve later in life take over as dominant risk factors,” he wrote.
His assessment was stark: COVID-19 makes it hard to breathe, and excess fat only makes this worse.
“As a cardiologist who studies heart failure, I am struck by how many of the mechanisms that are mentioned in reviews of obesity risk and heart disease are also mentioned in reviews of obesity and COVID-19,” Kass wrote. Things like sleep apnea and increased inflammation are all at work, damaging lungs and particularly the air sacs that do the heavy lifting in the respiratory system.
Not only does being severely obese make it harder to breathe, but the adipose tissue fuels mechanisms that act like magnets for SARS-CoV-2, the virus that causes the COVID-19.
“Fat deposited in skeletal muscle may be sought after by top-end steakhouses but, in vivo, it compromises muscle metabolic efficiency, nutrient uptake, and performance,” Kass wrote. “It requires more muscle force to displace the diaphragm downward when a substantial fat mass lies below it. Abdominal obesity also makes it more difficult to breathe in a prone position that is favored to improve ventilation in patients with COVID-19.”
“Among more specific mechanisms is expression of angiotensin-converting enzyme (ACE) 2 protein in adipose tissue. This is the docking protein for SARS-CoV-2 to enter a cell, and fat has higher levels than the lungs and so may serve as a viral refuge and replication site, prolonging virus shedding,” he wrote.
The Kaiser Permanente authors noted that other trials are examining the role of certain mainstay therapies in COVID-19, including recombinant ACE2 and angiotensin II receptor blockers (ARBs).
They note that while fighting COVID-19 is the immediate task, it has pointed to the need to confront obesity. “Principally, we demonstrate the leading role severe obesity has over other highly correlated risk factors, providing a clear target for early intervention.
“Our findings also reveal the distressing collision of 2 pandemics: COVID-19 and obesity. As COVID-19 continues to spread unabated, we must focus our immediate efforts on containing the crisis at hand. Yet our findings also underscore the need for future collective efforts to combat the equally devastating, and potentially synergistic, force of the obesity epidemic.”
- Tartof SY, Qian L, Hong V. Obesity and mortality among patients diagnosed with COVID-19: results from an integrated health care organization. Ann Intern Med. Published online August 12, 2020. doi:10.7326/M20-3742
- Kass DA. COVID-19 and severe obesity: a big problem? Ann Intern Med. Published online August 12, 2020. doi:10.7326/M20-5677