Worldwide impact of COVID-19 on hospital admissions for non-ST-elevation acute coronary syndromes (NSTACS): a systematic review with meta-analysis of 553,038 cases

Background: How COVID-19 impacted non-ST-segment elevation acute coronary syndromes (NSTACS) is object of controversial reports. Aim: To systematically review studies reporting NSTACS hospitalizations during COVID-19 pandemic, and analyze whether differences in COVID-19 epidemiology, methodology of report, or public health-related factors could contribute to discrepant findings. Methods: Comprehensive search (MedLine, Embase, Scopus, Web-of-Science, Cochrane Register), of studies reporting NSTACS hospitalizations during COVID-19 pandemic compared with a reference period, following Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Data were independently extracted by multiple investigators and pooled using a random-effects model. Health-related metrics were from publicly available sources, and analyzed through multiple meta-regression modelling. Results: We retrieved 102 articles (553 038 NSTACS cases, 40 countries). During peak COVID-19 pandemic, overall Incidence Rate-Ratio (IRR) of NSTACS hospitalizations over reference period decreased (0.70, 95% CI 0.66-0.75; p < 0.00001). Significant heterogeneity was detected among studies (I2= 98%; p < 0.00001). Importantly, wide variations were observed among, and within, countries. No significant differences were observed by study quality, whereas comparing different periods within 2020 resulted in greater decrease ((IRR: 0.61; CI: 0.53-0.71) than comparing 2020 vs previous years (IRR: 0.74; CI 0.69-0.79). Among many variables, major predictors of heterogeneity were: Sars-Cov-2 reproduction rate/country, number of hospitals queried, reference period length; country stringency index and socio-economical indicators did not significantly contribute. Conclusions: During COVID-19 pandemic NSTACS hospitalizations decreased significantly worldwide. However, substantial heterogeneity emerged among countries, and within the same country. Factors linked to public health management, but also to methodologies to collect results may have contributed to this heterogeneity. Trial registration: The protocol was registered in PROSPERO International Prospective Register of Systematic Reviews (ID: CRD42022308159).