Asthma is associated with increased risk of intubation but not hospitalization or death in coronavirus disease 2019.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused considerable morbidity and mortality. COVID-19 often presents with respiratory symptoms; however, the role of asthma in COVID-19 has not been well established. Although studies from China suggested that asthma was not a risk factor for severe COVID-19, other studies have revealed higher rates of asthma among hospitalized patients. , Therefore, the primary aim of this study was to assess the associations between asthma and hospitalization, intensive care unit (ICU) admission, or death among patients with COVID-19. Secondary objectives were to assess the associations between asthma and intubation, duration of intubation and hospitalization, and inflammatory markers in COVID-19.

This retrospective study was conducted at the George Washington University School of Medicine and Health Sciences in Washington, DC, and approved by its institutional review board. Patients were identified by an electronic medical record search of positive SARS-CoV-2 polymerase chain reaction test results between March and May 2020. Patients with underlying lung disease other than asthma were excluded. Demographics, clinical history, and laboratory markers (trough white blood cell, platelet, and lymphocyte counts; peak D-dimer, ferritin, C-reactive protein [CRP], lactate dehydrogenase [LDH], and interleukin-6 [IL-6] levels) were collected. Diagnosis of asthma was based on the International Classification of Diseases, Tenth Revision codes and verified by clinical history by a board-certified allergist.

A total of 787 patients with confirmed SARS-CoV-2 were identified. A total of 60 patients were excluded owing to unknown medical history or pulmonary disease other than asthma, resulting in 727 patients in the final analysis. We assessed whether asthma was associated with hospitalization using a multivariable logistic regression model, adjusting for age, body mass index, race, and a number of comorbidities (chronic kidney disease, coronary artery disease or congestive heart failure, diabetes, and hypertension). In addition, we assessed whether asthma was associated with outcome severity after hospitalization using an adjusted proportional odds model. We used multivariate imputation by chained equations to generate 100 datasets with imputed values for 209 patients with missing body mass index measurements. The imputation model included all levels of outcome severity and the covariates in our primary regression models.

We assessed whether intubation was associated with asthma using a Fisher’s exact test, with exact confidence intervals. Differences in mean duration of hospitalization and intubation were compared using 2-sided t tests. We used Wilcoxon ranked sum tests to assess the relationship between biomarkers and asthma. Statistical significance was summarized using nominal P values. All analyses were carried out using the R software, version 4.0.2 (The R Foundation, Vienna, Austria).

Of the 727 patients, 274 (37.6%) were admitted to the hospital but did not require ICU-level care, 68 (9.3%) required ICU care but were discharged, and 61 (8.3%) died. A total of 105 patients (14.4%) had asthma. The proportion of patients with asthma treated as an outpatient vs those hospitalized were similar (14.6% vs 14.2%, respectively). Patient characteristics are summarized in Table 1 .

Table 1

Clinical Characteristics

Characteristic	Overall, N = 727 (100%)	Non asthma, N = 622 (85.6%)	Asthma, N = 105 (14.4%)
Age, mean (SD)	49.46 (17.93)	49.95 (18.16)	46.61 (16.28)
BMI, mean (SD)	30.56 (8.14)	29.91 (7.57)	33.73 (9.92)
Allergic asthma	36 (4.9)	0 (0.0)	36 (34.3)
Race
White	82 (11.3)	75 (12.0)	7 (6.7)
African American	380 (52.2)	315 (50.6)	65 (61.9)
Asian	31 (4.3)	29 (4.7)	2 (1.9)
Latino	70 (9.6)	61 (9.8)	9 (8.6)
Other or unknown	164 (22.6)	143 (23.0)	22 (21.0)
Risk factors
CKD	63 (8.7)	58 (9.3)	5 (4.8)
Diabetes	165 (22.7)	145 (23.3)	20 (19.0)
CHF or CAD	27 (3.7)	26 (4.2)	1 (1.0)
HTN	278 (38.2)	243 (39.0)	35 (33.3)
Number of risk factors
0	405 (55.7)	342 (54.9)	64 (61.0)
1	157 (21.6)	132 (21.2)	25 (23.8)
2	104 (14.3)	92 (14.8)	12 (11.4)
3	44 (6.0)	41 (6.6)	3 (2.9)
4	15 (2.1)	14 (2.2)	1 (1.0)
5	2 (0.3)	2 (0.3)	0 (0.0)
Outcomes
Hospitalization with eventual discharge	274 (37.6)	235 (37.7)	39 (37.1)
ICU admission with eventual discharge	68 (9.3)	57 (9.1)	11 (10.5)
Death	61 (8.4)	51 (8.2)	10 (9.5)
Hospital length of stay	9.89 (9.14)	9.70 (8.91)	11.11 (10.46)
Intubation	44 (6.1)	33 (5.3)	11 (10.5)
Intubation length	11.14 (8.52)	11.32 (8.56)	10.44 (8.83)

Abbreviations: BMI, body mass index; CAD, coronary artery disease; CHF, congestive heart failure; CKD, chronic kidney disease; HTN, hypertension; ICU, intensive care unit.

Asthma was not significantly associated with hospitalization, ICU admission, or death. The adjusted odds of hospitalization among the patients with asthma was 1.4 times higher than those without asthma (95% confidence interval [CI], 0.82-2.4; P = .22). The adjusted odds of death vs either hospitalization or ICU admission or equivalently of death or ICU admission vs hospitalization was 1.3 times higher among patients with asthma (95% CI, 0.6-2.8; P = .48). Age, number of comorbidities, and race (non-White vs White; P = .01) were associated with increased odds of hospitalization.

The odds of intubation were 2-fold higher among patients with asthma than those without asthma (odds ratio, 2; 95% CI, 1-fold to 4-fold; P = .047). However, there was no significant difference in duration of intubation (P = .44) or hospitalization (P = .44). Asthma was associated with a higher platelet count (208 vs 191; P = .046). However, there was no association between asthma and leukopenia (P = .43), lymphopenia (P = .26), CRP (P = .44), D-dimer (P = .36), LDH (P = .43), ferritin (P = .31), or IL-6 (P = .19). Furthermore, we were unable to evaluate the association between biologic medications for asthma and COVID-19 outcomes, as only 1 patient with asthma was receiving a biologic (omalizumab) and did not require hospitalization.

This study assessed whether asthma was associated with COVID-19 severity with regard to outcomes and laboratory biomarkers. The proportion of patients with asthma and COVID-19 treated as an outpatient vs those hospitalized was similar. Our patients had a slightly higher prevalence of asthma than the overall prevalence of asthma in Washington, DC (14.4% vs 11%, respectively), suggesting asthma may confer a slightly increased risk of contracting COVID-19. Even with the higher prevalence, asthma was not associated with hospitalization, ICU admission, or death. This is consistent with the study by Chhiba et al that also did not find an association between asthma and risk of hospitalization.

In this study, patients with asthma were more likely to be intubated than those without asthma. This may reflect a lower threshold for intubating patients with asthma rather than more severe clinical disease. Mahdavinia et al found a longer duration of intubation among patients with asthma, but our study revealed no association between asthma and duration of intubation or hospitalization.

Inflammatory markers, including leukopenia and lymphopenia, have been associated with severe COVID-19. Chhiba et al found that patients with asthma had significantly lower levels of ferritin, CRP, and LDH than those without asthma with COVID-19. However, we did not find an association between asthma and laboratory parameters except for thrombocytopenia, which was likely not clinically significant.

Regarding study limitations, this was a retrospective study at a single medical center. We only had access to the electronic medical record from this center and were unable to identify the patients who may have been hospitalized at other institutions. Because this was a retrospective study, we are unable to make any causative associations.

In conclusion, there was no association between asthma and risk of hospitalization, ICU admission, or death among patients with COVID-19. Asthma was associated with increased odds of intubation, but not with duration of intubation or hospitalization. This study adds to the growing literature that patients with asthma may not be at a higher risk of severe outcomes with COVID-19.