Table 1.
The general characteristics of the 22 included studies.
| Author | Year | Study type | Country | Sample size | The prevalence of SCH | Time points of assessment of thyroid parameters | The cut-off for TSH in SCH (mIU/L) |
|---|---|---|---|---|---|---|---|
| Sitoris G. et al. ( 3 ) | 2020 | prospective cohort study | Belgium | 1521 | 10.45% | <G20w | >2.51 |
| Li M.F. et al. ( 10 ) | 2020 | retrospective cohort study | China | 1556 | 37.6% (2011ATA), 9.77% (2017ATA) | T1 | >2.5 (2011ATA), >4 (2017ATA) |
| Lai H., Z.Y. et al. ( 26 ) | 2020 | prospective cohort study | China | 1226 | 5.79% | T1 | >3.0 |
| Wu M.Q. et al. ( 11 ) | 2019 | retrospective cohort study | China | 6157 | 2.68% | T1, T2 | >4.432 (T1),>4.053(T2) |
| Cakmak et al. ( 4 ) | 2019 | retrospective cohort study | Turkey | 8916 | 10.43% | T1 | >2.5 |
| Gupta R. et al. ( 23 ) | 2018 | prospective cohort study | India | 1268 | 11.20% | <G20w | T1:>2.5 T2:>3.0 |
| Furukawa S. et al. ( 21 ) | 2017 | retrospective cohort study | Japan | 745 | 22.41% | <G20w | >3 |
| Hebbar S. et al. ( 24 ) | 2017 | prospective cohort study | India | 171 | 45.40% | T1 | >2.5 |
| Zhang et al. ( 7 ) | 2016 | retrospective cohort study | China | 3562 | 1.67% | T1 | >4.08 |
| Kishore R. N.et al. ( 32 ) | 2015 | prospective cohort study | India | 263 | 6.08% | T1 | >2.5 |
| Ajmani S.N. et al. ( 16 ) | 2014 | prospective cohort study | India | 400 | 9.00% | T2 | >3.0 |
| Chen L.M. et al. ( 19 ) | 2014 | prospective cohort study | China | 8012 | 4.63% | T1,T2,T3 | >3.47 (T1),>3.81(T2),>4.99(T3) |
| Saki F. et al. ( 29 ) | 2014 | prospective cohort study | Iran | 600 | 11.30% | T2 | >3 |
| Breathnach F.M. et al. ( 17 ) | 2013 | prospective cohort study | Ireland | 904 | 1.77% | <G20w | >4.1 |
| Goel P. et al. ( 22 ) | 2012 | prospective cohort study | India | 1005 | 3.40% | T1,T2,T3 | T1>5.0,T2>5.78,T3:5.7 |
| Wang S. et al. ( 30 ) | 2012 | retrospective cohort study | China | 756 | 26.49% | T1 | >2.5 |
| Karakosta P. et al. ( 25 ) | 2012 | prospective cohort study | Greece | 1170 | 6.92% | <G20w | T1:>2.53 T2:>2.73 |
| Wilson K.L. et al. ( 33 ) | 2012 | retrospective cohort study | USA | 24883 | 2.12% | <G20w | >4.13 |
| Mannisto et al. ( 27 ) | 2010 | prospective cohort study | Finland | 5805 | 3.90% | <G20w | >3.6 |
| Sahu M.T. et al. ( 28 ) | 2010 | prospective cohort study | India | 633 | 6.47% | T2 | >5.5 |
| Cleary-Goldman J. et al. ( 20 ) | 2008 | prospective cohort study | USA | 21980 | 2.20% | T1,T2 | >4.29 (T1),>3.94(T2) |
| Casey B.M. et al. ( 18 ) | 2005 | prospective cohort study | USA | 17298 | 2.33% | <G20w | >2.74 |