Table 1.
Characteristics of included studies
| Authors | N | Perforated | Date | Study interval time | Country |
|---|---|---|---|---|---|
| Schäfer FM et al. (11) | 338 | 70 | 2021 | March 2018 to May 2019 | Germany (Bavaria) |
| Fisher JC et al.(12) | 1291 | 351 | 2021 | Jan 2014 to June 2019 | US |
| Gerall CD et al. (13) | 41 | 4 | 2021 | March to May 2019 | US / New York city |
| Theodorou CM et al. (14) | 592 | 239 | 2021 | Pre-COVID era | US /California |
| Horst KK et al. (15) | 59 | 6 | 2021 | March 1 to May 31 2019 | US /Rochester, Minnesota |
| Esparaz JR et al. (16) | 102 | 26 | 2021 | March to May 2019 | US /Alabama |
| Ali S et al. (17) | 112 | 8 | 2020 | March to May 2019 | Pakistan/Peshawar |
| Place R et al. (18) | 70 | 13 | 2020 | March 16 to June 7 2019 | US/ Northern Virginia |
| Aarabi S et al. (19) | 19019 | 5282 | 2011 | 2000 to 2006 | New England |
| Deng Y et al. (20) | 31457 | 10524 | 2010 | 1997 | US |
| Guagliardo MF et al. (8) | 9069 | 2986 | 2003 | 1995 and 1997? | US / New York and California |
| Cheong LH et al. (21) | 120117 | 32321 | 2014 | 2004 to 2010 | US and Canada |
| Schäfer FM et al. (11) b | 176 | 49 | 2021 | 2020 | Germany (Bavaria) |
| Fisher JC et al. (12)b | 55 | 25 | 2021 | Jan and May 2020 | US |
| Gerall CD et al. (13)b | 48 | 7 | 2021 | March to May 2020 | US / New York city |
| Theodorou CM et al. (14) b | 606 | 255 | 2021 | 2019 vs 2020 | US /California |
| Horst KK et al. (15)b | 51 | 14 | 2021 | March 1 to May 31 2020 | US / Rochester, Minnesota |
| Esparaz JR et al. (16)b | 103 | 47 | 2021 | March to May 2020 | US /Alabama |
| Ali S et al. (17)b | 42 | 23 | 2021 | March to May 2020 | Pakistan/Peshawar |
| Place R et al. (18) b | 90 | 35 | 2021 | March 16 to June 7 2020 | US/ Northern Virginia |
N: number. b, same study containing cohorts of both Pre-COVID and post-COVID eras.