The impact of comorbid allergic airway disease on the severity and mortality of COVID-19: a systematic review and meta-analysis

PURPOSE: To analyze the impact of AAD on the severity and mortality of COVID-19 patients and compare clinical outcomes between patients with and without AAD. METHODS: In the systematic review and meta-analysis, we searched PubMed, Embase, Web of Science for studies reporting allergic rhinitis, asthma prevalence in COVID-19 patients and compared clinical outcomes, and excluded duplicate publications, reviews, comments, single or few cases reports (< 100 cases). We determined the pooled effect estimates using random effect model. RESULTS: Thirty-four studies (345,091) were finally included for the meta-analysis. On the basis of 32 studies (337,821) involving with the severity of COVID-19, we did not find significant association between AAD and the severity of COVID-19 (p = 0.35, OR 1.10, 95% CI 0.90–1.35). Subgroup analysis indicated there was no the variability in the prevalence of AAD among COVID-19 patients in different study designs, disease categories, countries, the definition of severity, and population size of AAD. Based on 21 studies (306,331) involving with the mortality of COVID-19, AAD was significantly associated with the decreased mortality of COVID-19 (p < 0.05, OR 0.83, 95% CI 0.70–0.99). The subgroup analysis showed AAD was not associated with the mortality of COVID-19 in different countries or regions. Based on the population size of AAD, we found AAD within 100 cases was not associated with the mortality of COVID-19 (p = 0.63, OR 1.15, 95% CI 0.65–2.03). Moreover, study design was possible heterogeneity source as the heterogeneity I(2) was reduced to 0 in prospective studies. CONCLUSION: The preexisting AAD was not inclined to deteriorate the course of COVID-19. The prevalence of AAD was not associated with the severity of COVD-19 patients and inclined to be significantly associated with the decreased mortality risk of COVID-19. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00405-021-07072-1.