2.3 Statistical analysis
We used Stata 12.0 software (Stata Corp, College Station, TX, USA) for the meta-analysis. We undertook a meta-analysis of the prevalence and clinical outcomes of COVID-19 among individuals with ARDs from observational by using a random effects model. We evaluated the presence of heterogeneity across studies by using the I2 statistic. An I2 value of <25% indicates low heterogeneity, 25%–75% as moderate heterogeneity, and >75% as considerable heterogeneity. A random effects regression model was used to assess the contributions of each potential risk factor and medication class to the prevalence and adverse clinical outcomes. Since the medication regimen of each patient in the included studies could not be obtained, we regarded the drugs used by the patients as the drugs used by all patients in the studies, regardless of the proportion of the number of people who have used the drugs in the studies. Besides, we regarded the drugs used by more than 50% of the patients in this study as the primary drugs used by all patients.