Table 2.
Demographics of included studies.
| Study | Country | Study design | Describe population | Age | Sex ‐number of women/girls | Sex ‐number of men/boys | Overall quality rating |
|---|---|---|---|---|---|---|---|
| Azlan (2020) | Malaysia | Cross sectional | General public (n = 4850) | M = 34 years (SD = 11.2, range = 18–73) | 2808 | 2042 | Low risk of bias |
| Brankston (2020) | Canada | Cross sectional | General public (n = 4981) | 18‐29 years (15.7%) | 50.6% | 49.1% | Low risk of bias |
| Davis (2021) | USA | Cross sectional | University students (n = 595) | M = 24.86 (SD = 10.62) | 441 (73.4%) | 143 (23.8%) | Unclear risk of bias |
| Goldberg (2020) | USA | Longitudinal | General public (n = 3933) |
M = 47 years (April 3–4) M = 46 years (April 5–7) |
53% (April 3–4) 56% (April 5–7) | 47% (April 3–4) 44% (April 5–7) | Low risk of bias |
| Gray (2020) | New Zealand | Cross sectional | General public (n = 1015) | 23.3% of respondents were aged 25–34 years | 592 (58.3%) | 416 (41%) | Low risk of bias |
| Hao (2021) | USA | Cross sectional | General public (n = 2047) | Not reported | Not reported | Not reported | Low risk of bias |
| Iqbal (2021) | Pakistan | Cross sectional | General public (n = 1789) | M = 23.4 years (SD = 8.23) | 949 (53.05%) | 840 (46.95%) | High risk of bias |
| Jang (2020) | Korea | Cross sectional | General public (n = 2002) | 19–29 (18.3%) | 505 | 497 | Low risk of bias |
| Kowalski (2020) | Poland | Cross sectional | General public (n = 507) | M = 44.07 (SD = 14.41) | 253 | 254 | Low risk of bias |
| Krupic (2021) | Croatia | Cross sectional | General public (n = 500) | M = 27.92 (SD = 9.30). | 341 females | 159 males | Low risk of bias |
| Lee (2020) | South Korea | Cross sectional | General public (n = 973) | M = 46.41 (14.94) | 50% 487 | 50% 486 | Low risk of bias |
| Mahalik (2021) | USA | Cross sectional | Men (n = 596) | (M = 31.33, SD = 10.59) | 100% | Unclear risk of bias | |
| Milad (2021) | USA | Longitudinal | General public (n = 451) | M = 45.40 (SD = 15.78) | Not stated | Not stated | Unclear risk of bias |
| Mo (2021) | China | Cross sectional | Pregnant women (n = 4087) |
Two‐thirds (2743/4087, 67.1%) of the participants were aged 30 years or less. |
4087 | No men in sample | Unclear risk of bias |
| Mousavi (2021) | Afghanistan | Cross sectional | General public (n = 450) | 17–26 years (65.8%) | 138 (28.4%) | 322 (71.6%) | Unclear risk of bias |
| Muslih (2021) | Indonesia | Cross sectional | General public (n = 1033) | 17–29 years: 552 (53.4%) >30 years: 481 (46.6%) | 649 (67.2%) | 339 (32.8%) | Unclear risk of bias |
| O'Brien (2021) | USA | Cross sectional | General public (n = 450) | M = 36.68 (range 18–76) | 38% | 62% | Unclear risk of bias |
| Rieger (2020) | Germany | Cross sectional | University students and staff (n = 206) | M = 26 (range 14–62) | 66% | Not reported | Unclear risk of bias |
| Stosic (2021) | USA | Cross sectional | General public (n = 1629) | Not reported | Not reported | Not reported | Low risk of bias |
| Tran (2020) | France | Cross sectional | Adults with chronic conditions (n = 7169) | M = 46.1 (14.7) years |
5616 (78.3%) |
Not reported | Unclear risk of bias |
| Varghese (2021) | Europe: Germany, UK, Denmark, Netherlands, France, Portugal, Italy | Cross sectional | General public (n = 7500) | Not reported | Not reported | Not reported | High risk of bias |
| Zhong (2020) | China | Cross sectional | General public (n = 6910) |
M = 33.0 years (SD 10.7, range: 16–87) |
65.7% | 34.3% | High risk of bias |
| Zhou (2021) | China | Cross sectional | Residents of Wuhan City (n = 728) | 36–50 years (44.0%) | 416 (57.1%) | 312 (42.9%) | Unclear risk of bias |