| S. no. | Study | Study design | Study country | Sample size | Age groups | Sex (M : F) | Available variables | Result of the study |
| 1 | Chhiba et al. [15] | Retrospective cohort | United States of America | 1542 | <40, 40–70, >70 | 9 : 10 | Mortality | Statistically no association with increased risk of mortality due to COVID-19 in asthmatics | 2 | Stephanie et al. [16] | Retrospective cohort | United States of America | 1298 | 51 | 15 : 10 | Intubation, mortality | Similar association with intubation and statistically lower risk of mortality in asthma | 3 | Song et al. [17] | Retrospective cohort | Wuhan, China | 961 | 63 (49,70) | 11 : 10 | Intubation, mortality | The risk of intubation and mortality were statistically insignificant in asthmatics | 4 | Mahdavinia et al. [18] | Cohort | United States of America | 935 | 18–65 | 8 : 10 | Intubation, mortality | Statistically, a higher risk of being intubated but a lower risk of mortality in asthma | 5 | Beurnier et al. [19] | Prospective cohort | France | 112 | 54 (42,67) | 3 : 7 | ICU admission, intubation, death | No significant association with increased risk of ICU admission, intubation, and mortality in asthma | 6 | Doriane et al. [20] | Retrospective cohort | Belgium | 596 | 53 ± 18 | 9 : 10 | ICU admission, mortality | Insignificant association between asthma and risk of ICU admission and mortality | 7 | Calderon et al. [21] | Cross-sectional | Spain | 6310 | 55 ± 20 | 4 : 10 | Mortality | Similar association with mortality | 8 | Choi et al. [22] | Retrospective cohort | Korea | 7590 | 55.5(41,71) | 6 : 10 | ICU admission, mortality | Statistically higher association with ICU admission and mortality from COVID-19 in asthma. | 9 | Bloom et al. [23] | Prospective cohort | United Kingdom | 8950 | 16–49 | 13 : 10 | ICU admission, intubation | No association with increased risk of ICU admission and intubation due to COVID-19 in asthma | 10 | Robinson et al. [24] | Cohort | United States of America | 3248 | ≥18 | 3 : 10 | Intubation, mortality | Lower association with risk of intubation and mortality in asthma | 11 | Castilla et al. [25] | Prospective cohort | Spain | 35387 | <15, 15–65, >65 | 9 : 10 | ICU admission, mortality | Insignificant association with ICU admission and mortality in asthma | 12 | Almazeedi et al. [26] | Retrospective cohort | Kuwait | 1096 | 41(25–57) | 42 : 10 | ICU admission, mortality | Significant association with ICU admission and mortality in asthma | 13 | Mather et al. [27] | Retrospective cohort | United States of America | 1045 | NR | NR | Intubation, mortality | Insignificant association with increased risk of intubation in asthma | 14 | Lee et al. [28] | Retrospective cohort | Korea | 7272 | >20 | 6 : 10 | ICU admission, intubation, mortality | Significantly higher risk of ICU admission, intubation, and mortality in asthma | 15 | Uribe et al. [29] | Cohort | United States of America | 961 | 66(52,78) | 9 : 10 | ICU admission, intubation, mortality | Lower rates of ICU admission, intubation, and mortality in asthma. Insignificant statistical association | 16 | Brinton et al. [30] | Retrospective cohort | United States of America | 345 | 49 ± 6 | NR | Intubation, mortality | Equal association with risk of intubation and mortality between asthmatic and nonasthmatic patients | 17 | Kipourou et al. [31] | Prospective cohort | Kuwait | 3995 | 41 ± 7 | 24 : 10 | ICU admission, mortality | Statistically significant risk of ICU admission and mortality in asthma | 18 | Schonfeld et al. [32] | Retrospective cohort | Argentina | 207079 | 41(2,55) | 9 : 10 | ICU admission, mortality | Similar association of risk of ICU admission mortality in asthma | 19 | Rosenthal et al. [33] | Retrospective cohort | United States of America | 727 | 46.61 | NR | ICU admission, intubation, mortality | Higher association with risk of ICU admission, intubation, and mortality in asthma |
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