If you, like the Skeptical Cardiologist, suffer from asthma you may be wondering if you are at a higher risk of contracting COVID-19 or developing more severe respiratory complications from the disease once infected.
There are 25 million asthma sufferers in the United States, about 8% of the population, and many of us are using as primary treatment a combination of inhaled beta-agonists (for immediate relief) and inhaled corticosteroids (ICS, for long-term conditioning of the lung).
How are these treatments influencing our risks during the COVID-19 pandemic?
A published online in Lancet Respiratory Medicine suggested that there is a lower prevalence of asthma in patients with COVID-19. However, the sum of evidence from this commentary and elsewhere is insufficient to say asthma is protective.
When there is an absence of evidence, as we saw with as a risk factor and as a treatment, the tendency of journalists is to obtain a quote from a physician who has treated patients with COVID-19 to buttress a particular argument. Quotes which say something like "we don't know" or "there is not enough evidence right now" are highly unlikely to be published, whereas anecdotal speculation is always intriguing (but often misleading.). The published this quote on the topic:
"We're not seeing a lot of patients with asthma," said Dr. Bushra Mina, a pulmonary and critical care physician at Lenox Hill Hospital in New York City, which has treated more than 800 COVID cases. The more common risk factors, he added, are "morbid obesity, diabetes and chronic heart disease."
A major problem in sorting out asthma as an independent risk factor is that many papers are lumping all "chronic respiratory diseases" together, which puts asthma in a bucket with chronic obstructive pulmonary disease (COPD) and interstitial lung disease like pulmonary fibrosis. There are striking differences in the demographics and prognosis of these diseases. For example, patients with COPD are older and much more likely to have smoked cigarettes, two factors clearly associated with COVID-19 risk.
In addition, asthma in older adults is highly associated with obesity, a well-recognized independent risk factor for COVID-19 complications.
The American Academy of Allergy, Asthma, and Immunology (AAAAI) states: "Among adults aged 60 and over, there was a significant trend of: 7.0% among normal weight adults; 9.1% among overweight adults; 11.6% among adults with obesity."
In addition, almost no data are available on asthma stratified by severity and treatment. The severe asthma patient who requires oral corticosteroids is markedly different from the mild asthmatic whose only treatment is intermittent inhaled beta-agonists.
These data, like the data on hypertension, should be taken with a grain of salt. But at a minimum, we can say there is no signal that asthma by itself increases the risk of COVID-19 infection.
Inhaled Corticosteroids and COVID-19
The authors of the commentary in Lancet Respiratory Medicine that implied asthma (and chronic respiratory disease) was protective against COVID-19 infection also concluded that "the possibility that inhaled corticosteroids might prevent (at least partly) the development of symptomatic infection or severe presentation of COVID-19 cannot be ignored."
They cited some very preliminary data to support this contention, writing that "in in-vitro models, inhaled corticosteroids alone or in combination with bronchodilators have been shown to suppress coronavirus replication and cytokine production. Low-quality evidence also exists from a case series in Japan, in which improvement was seen in three patients with COVID-19 requiring oxygen, but not ventilatory support." Note that the authors of the commentary seem to have heavy ties to companies that stand to profit from sales of ICS.
Personally, I have always worried that my use of ICS put me at a higher risk of respiratory infections because corticosteroids are potent immunosuppressives, potentially lowering my immune response to bacterial, viral, or fungal infections. A 2019 meta-analysis in Infection found a in patients using ICS.
Due to these concerns, when the pandemic began I purposely cut back on my fluticasone/salmeterol (Advair) usage. Fortunately, my asthma has been very mild since I started taking 3 years ago. Since then, dupilumab has been approved for treatment of asthma. By the way, dupilumab is a targeted biologic therapy that inhibits signaling of interleukin-4 (IL-4) and interleukin-13 (IL-13) -- two key proteins that may play a central role in type 2 inflammation that underlies atopic dermatitis and several other allergic diseases -- but we have no idea if it increases or decreases COVID-19 risks or complications.
Does ICS usage increase or lower our risk of COVID-19 outcomes?
This figure from a of the topic in the European Respiratory Journal shows where in the process ICS could influence COVID-19, either increasing or decreasing risk of 1) initial infection, 2) progression to pneumonia, or 3) progression to acute respiratory distress syndrome and death once pneumonia is established.
There are theoretical arguments to suggest the use of ICS could either improve or worsen all three stages.
The review of 59 publications on COVID-19 concluded: "Following examination of the full texts including translations of those in Chinese, no publications were identified as having data on prior ICS use in patients with SARS, MERS or COVID-19 infection. No data were available for either a qualitative or narrative answer to the review question."
The bottom line right now is that we don't know if ICS use is an important risk factor in COVID-19 outcomes.
Should ICS Stay or Go?
The recommendations from the CDC, and all pulmonary/asthma societies, at this point is to stick to your current asthma action plan. If that includes taking an ICS, keep on taking it at current levels.
In fact, the AAAAI and other major asthma or pulmonary organizations emphasize that patients because experiencing an exacerbation event and the need for hospitalization, in those who become poorly controlled, could actually increase patient exposure and the risk of infection.
I've gone back to taking my ICS at pre-pandemic levels and I don't consider that my asthma puts me at any higher risk during the pandemic.
, is a private practice noninvasive cardiologist and medical director of echocardiography at St. Luke's Hospital in St. Louis. He blogs on nutrition, cardiac testing, quackery, and other things worthy of skepticism at , where a version of this post first appeared.