The study design was an observational, population-based cohort study in England. Electronic health records from primary care practices and death registrations were analyzed using OpenSAFELY, a data platform created for real-time analysis during the COVID-19 pandemic. Patients 18 years or older diagnosed with either rheumatoid arthritis or systemic lupus who regularly used hydroxychloroquine were included. The control group consisted of patients with the same conditions who did not regularly use hydroxychloroquine. A Cox regression was utilized to assess the association between the use or non-use of hydroxychloroquine before the pandemic and COVID-19 mortality risk.