The Association of Asthma With COVID-19 Mortality: An Updated Meta-Analysis Based on Adjusted Effect Estimates

BACKGROUND: The association of asthma with the risk for mortality among coronavirus disease 2019 (COVID-19) patients is not clear. OBJECTIVE: To investigate the association between asthma and the risk for mortality among COVID-19 patients. METHODS: We performed systematic searches through electronic databases including PubMed, EMBASE, and Web of Science to identify potential articles reporting adjusted effect estimates on the association of asthma with fatal COVID-19. A random-effects model was conducted to estimate pooled effects. Sensitivity analysis, subgroup analysis, meta-regression, Begg's test and Egger's test were also performed. RESULTS: Based on 62 studies with 2,457,205 cases reporting adjusted effect estimates, COVID-19 patients with asthma had a significantly reduced risk for mortality compared with those without it (15 cohort studies: 829,670 patients, pooled hazard ratio [HR] = 0.88, 95% confidence interval [CI], 0.82-0.95, I(2) = 65.9%, P < .001; 34 cohort studies: 1,008,015 patients, pooled odds ratio [OR] = 0.88, 95% CI, 0.82-0.94, I(2) = 39.4%, P = .011; and 11 cross-sectional studies: 1,134,738 patients, pooled OR = 0.87, 95% CI, 0.78-0.97, I(2) = 41.1%, P = .075). Subgroup analysis based on types of adjusted factors indicated that COVID-19 patients with asthma had a significantly reduced risk for mortality among studies adjusting for demographic, clinical, and epidemiologic variables (pooled OR = 0.87, 95% CI, 0.83-0.92, I(2) = 36.3%, P = .013; pooled HR = 0.90, 95% CI, 0.83-0.97, I(2) = 69.2%, P < .001), but not among studies adjusting only for demographic variables (pooled OR = 0.88, 95% CI, 0.70-1.12, I(2) = 40.5%, P = .097; pooled HR = 0.82, 95% CI, 0.64-1.06, I(2) = 0%, P = .495). Sensitivity analysis proved that our results were stable and robust. Both Begg's test and Egger's test indicated that potential publication bias did not exist. CONCLUSIONS: Our data based on adjusted effect estimates indicated that asthma was significantly related to a reduced risk for COVID-19 mortality.