INTRODUCTION: There is significant interest in the use of angiotensin converting 
enzyme inhibitors (ACE-I) and angiotensin II receptor blockers (ARB) in 
coronavirus disease 2019 (COVID-19) and concern over potential adverse effects 
since these medications upregulate the severe acute respiratory syndrome 
coronavirus 2 host cell entry receptor ACE2. Recent studies on ACE-I and ARB in 
COVID-19 were limited by excluding outpatients, excluding patients by age, 
analyzing ACE-I and ARB together, imputing missing data, and/or diagnosing 
COVID-19 by chest computed tomography without definitive reverse transcription 
polymerase chain reaction (RT-PCR), all of which are addressed here.
METHODS: We performed a retrospective cohort study of 1023 COVID-19 patients 
diagnosed by RT-PCR at Stanford Hospital through April 8, 2020 with a minimum 
follow-up time of 14 days to investigate the association between ACE-I or ARB 
use with outcomes.
RESULTS: Use of ACE-I or ARB medications was not associated with increased risk 
of hospitalization, intensive care unit admission, or death. Compared to 
patients with charted past medical history, there was a lower risk of 
hospitalization for patients on ACE-I (odds ratio (OR) 0.43; 95% confidence 
interval (CI) 0.19-0.97; P = 0.0426) and ARB (OR 0.39; 95% CI 0.17-0.90; P = 
0.0270). Compared to patients with hypertension not on ACE-I or ARB, patients on 
ARB medications had a lower risk of hospitalization (OR 0.09; 95% CI 0.01-0.88; 
P = 0.0381).
CONCLUSIONS: These findings suggest that the use of ACE-I and ARB is not 
associated with adverse outcomes and may be associated with improved outcomes in 
COVID-19, which is immediately relevant to care of the many patients on these 
medications.