Literature review (table)
Data from the first epidemiologic studies of the COVID-19 pandemic in China apparently did not identify asthma as a risk factor of severe COVID-19.10,11 Of 171 children treated at Wuhan Children’s Hospital (Wuhan, China), three (1.8%) required intensive care and mechanical ventilation; all of those had underlying diseases but there was no asthma reference.12 The same data was found in a cross-sectional multicenter study carried out in 10 hospitals across Hubei province (China), including hospitalized children with COVID-19.13
Dong et al (China) in a nationwide case series of 2135 pediatric patients (mean age 7 years) with COVID-19 reported to the Chinese Center for Disease Control and Prevention from January 16, 2020, to February 8,2020 (Hubei Province), did not report any asthma case.14
In a survey of 140 adult-aged admitted with COVID-19 (China), the clinical characteristics and allergy status of patients was investigated. All patients were community-acquired cases. Hypertension (30.0%) and diabetes mellitus (12.1%) were the most common comorbidities. Drug hypersensitivity (11.4%) and urticaria (1.4%) were self-reported by several patients. Asthma or other allergic diseases were not reported by any of the patients and the authors concluded that allergic diseases and asthma were not risk factors for SARS-CoV-2 infection. Older age and high number of comorbidities, namely cardiovascular and metabolic diseases, were associated with COVID-19 severity.15 The same authors studied a larger sample of 290 confirmed COVID-19 adult patients hospitalized, and found only one patient with asthma (0,3%); once again hypertension and diabetes mellitus were the most frequently found comorbidities.16
In another retrospective, multicenter cohort study that included 191 adult inpatients with confirmed COVID-19 (Wuhan, China), 48% had at least one comorbid disease, hypertension being the most common, followed by diabetes and coronary heart disease, with no asthma reference.17 In a survey of 70 adult patients admitted with COVID-19 in the Tongji Hospital (Wuhan, China), a 0.9% asthma prevalence was found, markedly lower than that in the adult population of this region (6.4%).18 In this study, asthma was not identified as a risk factor for disease severity, in contrast with hypertension.18
A nationwide analysis from China,19 including 1,590 COVID-19 cases from 575 hospitals in 31 provincial administrative regions were collected, with an overall rate of severe cases and mortality of 16.0% and 3.2%, respectively. The most prevalent comorbidity was hypertension (16.9%), followed by diabetes (8.2%). 130 (8.2%) patients reported having two or more comorbidities. None of the cases had physician-diagnosed asthma. After adjusting for age and smoking status, COPD [hazards ratio (HR) 2.681, 95% confidence interval (95%CI) 1.424-5.048], diabetes (HR 1.59, 95%CI 1.03-2.45), hypertension (HR 1.58, 95%CI 1.07-2.32) and malignancy (HR 3.50, 95%CI 1.60-7.64) were identified as significant severity risk factors, including for ICU admission, mechanical ventilation and death.19
In Europe, in a sample of 355 patients with COVID-19 who died in Italy (with a mean age of 79.5 years), it was reported that comorbidities were associated with increased mortality risk. 30% had ischemic heart disease, 35.5% had diabetes, 20.3% had active cancer, 24.5% had atrial fibrillation, 6.8% had dementia, and 9.6% had a history of stroke. Once again, no reference to chronic respiratory diseases was made, namely asthma or chronic obstructive pulmonary disease (COPD).20
Also in a retrospective case series of 1591 consecutive patients with laboratory-confirmed COVID-19 admitted in ICUs from 72 hospitals of the Lombardy Region, Italy, between February 20 and March 18, 2020, 68% of patients had at least 1 comorbidity. Hypertension was the most common comorbidity, affecting 49% of 1043 patients with available data. The second most common comorbidities were cardiovascular disease (21%) and hypercholesterolemia (18%). Only 4% had a history of COPD, with no reference with patients with asthma.21
In the CONFIDENCE study22 that included 100 pediatric COVID-19 cases also from Italy (median age 3,3 years), 58% with mild disease and only 1% with severe disease, there was no reference to chronic respiratory diseases as it was found in previous pediatric Chinese surveys by Lu et al12 and Dong et al.14
Barobia et al23 from La Paz University Hospital, Madrid, Spain, in a sample of 2226 adult patients (median age 61 years) admitted to the hospital who either died (20,7%) or were discharged (79,3%), identified that the most common comorbidity was hypertension (41.3%), followed by other chronic cardiovascular diseases (19,3%) and diabetes (17,1%); asthma was identified in 5,2% of COVID-19 patients, with a lower prevalence of 3,7% in the fatal cases. COPD affected 6,9% of the population with a prevalence of 14,1% in the fatal cases. Also from Spain, in Catalonia, Prieto-Alhambra et al24analyzed a primary care database covering >6 million people, including 121,263 COVID-19 patients, both hospitalized and outpatients. Most common comorbidities were hypertension (24.3%) and obesity (19.9%). Asthma was present in 6,8% of the patients and COPD in 3,2%. 10,7% of all patients were treated with inhalers.
In 200 COVID-19 patients hospitalized in the Lausanne University Hospital, Switerzland,25 an asthma prevalence of 4,0% was found, being 2,7% the asthma prevalence in those patients that required mechanical ventilation.
In the United States of America (USA), Bhatraju et al26 (Seattle) reported 24 patients with COVID-19 admitted to the intensive care unit (ICU) with a mortality rate of 50%. As coexisting disorders, 58% had diabetes, 22% were current or former tobacco smokers, 21% had chronic kidney disease, and 14% had asthma, corresponding to three cases with mild asthma who had been treated with systemic corticosteroids in the week before ICU admission, as outpatients, for a presumed asthma exacerbation. These patients were subsequently admitted to the ICU with severe respiratory failure requiring invasive mechanical ventilation.26
Arentz et al27 (Washington, USA), describe in a case series the characteristics and outcomes of 21 cases of COVID-19 admitted to the ICU at Evergreen Hospital, with a mean age of 70 years-old (range 43-92 years), being the more common comorbidities identified chronic kidney disease (47,6%), congestive heart failure (42,9), diabetes (33,3%) and COPD (33,3%). 2 patients had asthma (9,5%).
Data also from the USA regarding 345 cases in children (< 18 years) reported that 23% had at least one comorbidity.28 Chronic respiratory diseases, namely asthma, were the most common associated diseases, although the authors did not quantify the prevalence. Comorbidities were more frequently present in pediatric cases that required hospitalization compared to those that were not admitted to hospital (77% versus 12%), but there was no reference of asthma as a significant risk factor.28
In a sample of 377 adult COVID-19 patients admitted in California Hospitals (USA), 7,4% had non discriminated asthma or COPD.29 Data analysis of patients hospitalized in 14 states of the USA with COVID-19, during March 2020 (n=1,482),30 confirmed that hospitalization was much more frequent in adults (74.5% with ≥ 50 years). Among patients with information on underlying conditions (n=120), 89% had one or more comorbidities. The most common were hypertension and other cardiovascular diseases (77.5%), followed by obesity (48.3%) and diabetes mellitus (28.3%). 17,0% of the COVID-19 positive patients had asthma and 10,7% COPD. According the Centers for Disease Control and Prevention (CDC) report, in admitted patients aged 18-49 years, obesity was the most prevalent underlying condition (59,0%), followed by asthma (27,3%).30
A report from eight hospitals (Georgia, USA), also summarized medical data for 305 adult patients with confirmed COVID-19 who were admitted during March 2020. Overall, 225 (73.8%) patients had underlying conditions. Hypertension (67.5%), diabetes (39.7%), other cardiovascular diseases (25.6%) and severe obesity (body mass index ≥40), which was present in 12.7% of patients. Asthma was identified in 10.5% of all patients (13.5% in patients aged 18-49 years-old, 13.1% in those aged 50-64 years-old and 6.0% in those aged ≥65 years-old, with no statistically significant differences) and COPD in 5.2%.31
In the large sample of hospitalized COVID-patients (>99% adults), that included 5700 patients hospitalized with COVID-19 in the New York City Area (NY), 14.2% were treated in the ICU, 12.2% received invasive mechanical ventilation and 21% died.32Asthma prevalence was found in 9,0% (with no reference of asthma severity / control) and COPD in 5,4%; most common comorbidities were hypertension (56,6%), obesity (41,7%) and diabetes (33,8%).32
In the NY Mount Sinai Hospitals an 8,2% prevalence of asthma was found in 2199 hospitalized patients, that was not significantly different in those that died (7,4%).33 Also in NY, in the first 1000 consecutive adult patients with a positive SARS-CoV-2 PCR test presented to the emergency department or were hospitalized at New York-Presbyterian/Columbia University Irving Medical Center between March 1 and April 5, 2020, an asthma prevalence of 11,3% was found, that was also not significantly different in those that were ICU admitted (12,3%).34
In the ISARIC Prospective Observational Cohort Study35with near real-time analysis, with the participation of 166 United Kingdom (UK) hospitals, 16,749 COVID-19 hospitalized patients were included between 6th February and 18th April 2020, mostly adults. The commonest comorbidities were chronic cardiac disease (29%), uncomplicated diabetes (19%), non-asthmatic chronic pulmonary disease (19%) and asthma (14%); 47% had no documented reported comorbidity. Increased age and comorbidities including obesity were associated with a higher probability of mortality.35
Very recent data from the OpenSAFELY Collaborative Study,36 identified asthma as a significant risk factor of death from COVID-19 in England, United Kingdom (UK). The authors conducted a cohort study that included 17,425,445 adults using national primary care electronic health record data linked to in-hospital COVID-19 death data (from the 1st February 2020 to the 25th April 2020). Increasing age was strongly associated with risk, with the ≥80 year-age group having more than 12-fold increased risk compared with those aged 50-59 years; most comorbidities were associated with higher risk of COVID-19 hospital death, including asthma (fully adjusted hazard risk (HR); 95% CI = 1,11(1.02-1.20, with a greater HR for those with recent use of an oral corticosteroid - 1,25(1,08-1.44)).36
Data from the UK Biobank,37 in a prospective case-control study, found an asthma prevalence of 17,9% in 605 COVID-19 hospitalized patients, mostly of them adults (asthma prevalence was of 13,5% in the control population) but the disease was not identified as an independent risk factor for COVID-19 hospitalization / severity, in contrast with hypertension and COPD. In the oldest population (≥65 year-old) included in the UK Biobank,38 the same tendency on asthma prevalence was found between patients COVID-19 hospitalized versus controls (18,2% versus 13,0%), but again asthma was not identified as an independent risk factor for severity.
In a report from the Middle East (Saudi Arabia)39 that included 150 hospitalized adult patients (mean age 46,1 years), it was found that 28.8% and 26.0% of the COVID-19 population had hypertension and diabetes respectively. The asthma prevalence was 2,7%, and one patient with asthma was admitted in the ICU.
In a study aiming to estimate the risk factors for hospitalisation and death in the Mexican population40 infected by SARS-CoV-2 (n=10554, mean age 46,5 year-old, 39,4% hospitalized and 9,2% fatal cases), hypertension was the most prevalent comorbidity found (21.7%), followed by obesity (20.15%) and diabetes (17.7%). Asthma prevalence was 3,6% of this population (3,1% in the hospitalized patients and in 3,2% in the fatal cases). Patients with hypertension, obesity, and diabetes were more likely to be hospitalised and die than people without these comorbidities. Once again asthma was not identified as an independent risk factor for hospitalization and/or mortality.40