We identified 183 records after implementing our search strategy in major databases and grey literature up to 19 May 2020. We assessed 34 full-text articles for potential inclusion in our systematic review and meta-analysis. After excluding 9 articles with reasons, including 2 previous systematic reviews and meta-analyses and a recently retracted paper, we ended up with 25 records to be included in our qualitative and quantitative synthesis. No completed randomized controlled trials were identified; thus, we included only observational studies in our synthesis.
Nine studies were conducted in Europe (UK, Italy, France, Spain, Belgium) [18,19,20,21,22,23,24,25,26], 7 studies took place in North America (the USA) [27,28,29,30,31,32,33], while 9 studies were conducted in Asia, mainly in China [31, 34,35,36,37,38,39,40,41]. Finally, we initially included in our quantitative synthesis a study utilizing data from an observational database from 169 hospitals in Asia, Europe, and North America, which was recently retracted and thus excluded from our analysis [42]. Summary of studies’ characteristics is provided in Table 1, while quality assessment with the use of NOS is provided in Table 2.
Table 1 Summary characteristics of included studies Table 2 Newcastle-Ottawa quality assessment Form regarding included studies Herein, we present the main findings of our quantitative synthesis.
ACE Inhibitors/ARBs vs. Non-ACE Inhibitors/ARBs and Outcomes of Clinical Significance
SARS-CoV-2 Testing Positive
Use of ACE inhibitors or ARBs is not associated with increased odds for testing positive for SARS-CoV-2 (OR = 0.99, 95% CI 0.83–1.17, I2 = 93%), as shown in Fig. 2a. Subgroup analysis according to region did not reveal any significant association between ACE inhibitors/ARBs use and SARS-CoV-2-positive testing (in Asia, OR = 0.76, 95% CI 0.54–1.07, I2 = 84%; in Europe, OR = 1.22, 95% CI 0.77–1.95, I2 = 97%; in North America, OR = 0.99, 95% CI 0.86–1.15, I2 = 62%). Inspection of the corresponding funnel plot for this primary outcome ruled out the presence of publication bias (supplementary figure 1).
Hospital Admission
Notably, use of ACE inhibitors or ARBs does not increase the odds for hospitalization in the context of SARS-CoV-2 infection (OR = 1.74, 95% CI 0.95–3.17, I2 = 96%), as depicted in Fig. 2b.
Severe or Critical Illness
Despite inconsistency in definitions and reporting across the included studies, it was observed that the use of either ACE inhibitors or ARBs is not associated with increased odds for severe or critical illness (OR = 0.86, 95% CI 0.64–1.16, I2 = 90%), as shown in Fig. 2c. Of note, use of ACE inhibitors/ARBs in Asia was associated with a significant reduction in the odds for severe or critical illness by 63% (OR = 0.37, 95% CI 0.16–0.89, I2 = 83%), whereas, such an association was not shown in Europe (OR = 1.12, 95% CI 0.51–2.47, I2 = 94%) and in North America (OR = 1.11, 95% CI 0.84–1.45, I2 = 85%).
ICU Admission
It was also demonstrated that administration of ACE inhibitors or ARBs does not increase the odds for admission to ICU (OR = 1.40, 95% CI 0.80–2.43, I2 = 86%), as shown in Fig. 2d. Notably, in subgroup analysis by region, it was shown that ACE inhibitors/ARBs use is associated with increased odds for ICU admission in North America (OR = 1.75, 95% CI 1.37–2.23, I2 = 0%), while this association appeared non-significant in Europe (OR = 1.11, 95% CI 0.33–3.79, I2 = 92%).
SARS-CoV-2-Related Death
Of note, use of ACE inhibitors or ARBs does not increase the odds for SARS-CoV-2-related death (OR = 1.06, 95% CI 0.63–1.43, I2 = 83%), as depicted in Fig. 2e. However, in subgroup analysis by region, it was shown that ACE inhibitors/ARBs use increases the odds for death in Europe by 68% (OR = 1.68, 95% CI 1.05–2.70, I2 = 82%), it decreases the corresponding odds in Asia by 38% (OR = 0.62, 95% CI 0.39–0.99, I2 = 0%), whereas the association remains non-significant in the USA (OR = 0.95, 95% CI 0.63–1.43, I2 = 84%).
Another Dilemma: ACE Inhibitors or ARBs
SARS-CoV-2 Testing Positive
No significant difference was detected in the odds for SARS-CoV-2-positive testing among users of ACE inhibitors or ARBs (OR = 0.96, 95% CI 0.87–1.05, I2 = 38%), as shown in Fig. 3a. Notably, no significant difference was observed in the subgroup analysis by region (in Asia, OR = 1.08, 95% CI 0.81–1.45, I2 = 0%; in Europe, OR = 0.91, 95% CI 0.73–1.14, I2 = 68%; and in North America, OR = 1.01, 95% CI 0.90–1.12, I2 = 0%).
Admission to ICU
No significant difference in the odds for admission to ICU between subjects receiving ACE inhibitors or ARBs was detected (OR = 0.73, 95% CI 0.35–1.56, I2 = 43%), as depicted in Fig. 3b.
SARS-CoV-2-Related Death
Of interest, ACE inhibitors were found to be superior to ARBs in SARS-CoV-2-related death, although the result is marginally insignificant (OR = 0.86, 95% CI 0.74–1.00, I2 = 0%), as shown in Fig. 3c.