Studies investigating the association of asthma and COPD in coronavirus disease 2019 (COVID-19) patients
| Study | Study design | Location | Cohort | Setting | Results |
| Guan et al. [12] | Observational | China | COVID-19 positive; n=1590 | Hospital | Lower prevalence of COPD (1.5%) and asthma (0%) versus other comorbidities – hypertension (16.9%) and diabetes (8.2%) |
| Avdeev et al. [33] | Observational | Russia | COVID-19 (positive or pending with severe acute respiratory infection and typical CT); n=1307 | ICU | Low prevalence of bronchial asthma (1.8%) and COPD (3.1%), not higher than in the general population |
| Robinson et al. [34] | Observational | USA | COVID-19 positive; n=866 | Hospital | Hazard ratio 0.52 (95% CI 0.30–0.90) for ICU admission and 0.42 (95% CI 0.21–0.81) for mechanical ventilation for patients with asthma versus patients without asthma |
| Ho et al. [35] | Observational | USA | COVID-19 positive; n=10 523 | Hospital inpatient and outpatient | Odds ratio 0.43 (95% CI 0.28–0.64) for hospitalisation, 0.51 (95% CI 0.41–0.64) for ICU admission and 0.64 (95% CI 0.53–0.77) for mortality for patients with asthma versus patients without asthma |
| Cao et al. [36] | Observational | USA | COVID-19 positive; n=343 | Medical centre | Odds ratio 1.00 (95% CI 0.34–3.28) for hospitalisation, 0.59 (95% CI 0.31–1.08) for ICU admission, 1.10 (95% CI 0.56–2.12) for mechanical ventilation, 0.73 (95% CI 0.30–1.64) for in-hospital mortality due to COVID-19 for patients with asthma versus patients without asthma |
| Li et al. [37] | Observational | China | COVID-19 positive; n=548 | Hospital | Low proportion of patients with COVID-19 who had asthma (0.9%) |
| Izquierdo et al. [38] | Observational | Spain | Asthma; n=71 182 | EHRs: primary care, hospital inpatient, outpatient, emergency department | Odds ratio 2.29 (95% CI 4.35–6.66) for mortality for patients with asthma and COVID-19 versus patients with asthma without COVID-19 |
| Choi et al. [39] | Observational | South Korea | COVID-19 positive; n=7590 | Medical claims (including hospital inpatient and outpatient) | Patients with step 5 (more severe) asthma had a more prolonged stay in hospital versus patients with step 1 asthma |
| Butler et al. [40] | Observational | Ireland | COVID-19 positive; n=193 | Hospital | Prevalence of asthma (8.8%) versus general population (7.0%) |
| Sunjaya et al. [41] | Systematic review | Multiple countries | COVID-19 positive; n=349 592 overall, n=369 405 for risk ratio reduction analysis | Primary care, hospital, mixed | Prevalence of asthma was 7.46% (95% CI 6.25–8.67). Showed a 14% (95% CI 0.80–0.94) and 13% (95% CI 0.77–0.99) risk ratio reduction for acquiring and being hospitalised for COVID-19, respectively, for patients with asthma versus no asthma |
| Rogliani et al. [42] | Systematic review | Multiple countries | COVID-19 positive; n=8476 | Hospital | Relative risk of hospitalisation reduced in patients with asthma (0.86, 95% CI 0.77–0.97) and COPD (0.46, 95% CI 0.40–0.52) versus general population |
| Liu et al. [43] | Systematic review | Multiple countries | COVID-19; n=410 382 overall, n=5000 for risk ratio analysis | Nonhospital, hospital, ICU | Risk ratio 0.65 (95% CI 0.43–0.98) for mortality for patients with asthma versus patients without asthma |
CT: computed tomography; EHR: electronic health record; ICU: intensive care unit.