Introduction
The novel coronavirus SARS-CoV-2, which has caused a pandemic of coronavirus disease 2019 (COVID-19), has become a serious threat to human health globally. This disease particularly poses a tremendous hazard to individuals with coexisting comorbidities, including old age and chronic diseases such as hypertension, diabetes mellitus, and chronic lung diseases 1,2. Similar to SARS-CoV, SARS-CoV-2 utilizes angiotensin-converting enzyme-2 (ACE2) protein on the cell membrane as its host receptor3. Angiotensin-Converting Enzyme Inhibitors (ACEI) and Angiotensin II Receptor Blockers (ARB) are commonly used in hypertensive in COVID-19 patients with hypertension. Thus, there is an increasing interest in the potential effects of these drugs on the outcomes of patients with COVID-194. Recently, in a Chinese retrospective study, Zhang et al. reported ACEI/ARB to exhibit a remarkable association with reduced mortality of COVID-19 patients with hypertension5. A similar study by Li et al. showed ACEI/ARB not affecting the outcome of COVID-19 patients. However, there may be some differences between the use of ACEI vs. ARB on the outcomes. On the other hand, a previous study showed that the ACEI and ARB differed in the expression of ACE2 in an animal experiment6, suggesting the possibility of differential effects on COVID-19 patients. Of note, it has been reported that East Asian patients have higher incidence of ACEI-induced cough7. Therefore, ARB is the predominant drug used in China to block the renin-angiotensin-aldosterone system (RAAS). As the effect of ACEI/ARB on the outcomes of COVID-19 patients is still controversial, we aimed to assess the characteristics and clinical outcomes of patients with a history of hypertension treated with ACEI vs. ARB who developed COVID-19.