Study Inclusion and Exclusion

Two reviewers (MV & SW) independently screened all titles and abstracts. The relevance of each study was assessed according to the inclusion and exclusion criteria. Studies were included if they met the following criteria.

Studies including humans with COPD and/or asthma and a confirmed case (via polymerase chain reaction or antibody test) of COVID-19 were included in this review. Children <18 yrs and animal studies were excluded from this review. We also excluded studies on previous human coronaviruses: 229E, NL63, OC43, HKU1, MERS-CoV, and SARS-CoV.

Observational studies, including case-control and cohort studies were included. Randomized studies that reported the prognostic role of asthma/COPD in post-hoc analyses (e.g., Cox regression models) were also included.

Comparator groups include humans with confirmed COVID-19 and no evidence of COPD and/or asthma.

Studies had to report one or more of the following:

Number of COVID-19 cases hospitalised vs. COVID-19 cases non-hospitalised cases.

Number of hospitalised COVID-19 cases treated in intensive care unit (ICU) vs. hospitalsation but not admitted for ICU care.

Number of COVID-19 related deaths vs. survival.

Furthermore, studies were excluded if they were:

Not written in English.

Not peer reviewed (e.g., preprints).

Studies in a non-adult (<18 years) population.

Had insufficient data to calculate an adjusted odds ratio (aOR; adjusted for more than one COVID-19 related covariate) related to the stated outcomes.