Characteristics of included studies
| Characteristics | Studies (n) | % |
| Country | ||
| USA | 77 | 37.02 |
| France | 19 | 9.13 |
| China | 17 | 8.17 |
| Italy | 14 | 6.73 |
| England | 14 | 6.73 |
| Mexico | 11 | 5.29 |
| Multi-county | 8 | 3.85 |
| Brazil | 7 | 3.37 |
| Spain | 6 | 2.88 |
| Netherlands | 4 | 1.92 |
| Korea | 3 | 1.44 |
| Germany, Ireland, Kuwait, Saudi Arabia, Turkey | 2 | 0.96 |
| Argentina, Australia, Chile, Colombia, Democratic Republic of Congo, Egypt, Iran, Israel, Japan, Libya, Morocco, Peru, Qatar, Scotland, Singapore, Switzerland, Thailand | 1 | 0.48 |
| Study design | ||
| Prospective cohort | 35 | 16.83 |
| Retrospective cohort | 158 | 75.96 |
| Case–control | 5 | 2.4 |
| Cross-sectional | 10 | 4.8 |
| Study participants | ||
| General population | 168 | 80.77 |
| Restricted population* | 40 | 19.23 |
| Publication | ||
| Studies published in 2020 | 129 | 62.02 |
| Studies published in 2021 | 79 | 37.98 |
*Restricted by age, sex, race/ethnicity, disease or condition.