Summary of the characteristics of the included studies
| (A) | |||||||||||
| Author/year | Sample size | Region | Gender | Mean age (year) | Definition of SCH | SCH duration (months) | L-T4 dosage (initial value) | Treatment duration (months) | Thyroid function after treatment | CIMT (mm) (before/after) | Quality score |
| Monzani | 23 | Italy | Mixed genders | 37±11 | TSH >3.6 mIU/L | At least 6 months | 25–75 μg/day | 10.5* | Normal | 0.76±0.14 | 12 |
| 2004 | 0.67±0.13 | ||||||||||
| Soo-Kyung | 28 | Korea | Mixed genders | 36.0±6.2 | TSH >5.5 mIU/L | Newly diagnosed | 67 µg/day† | 18† | Normal | 0.67±0.11 | 9 |
| 2009 | 0.60±0.10 | ||||||||||
| Monica | 14 | Brazil | Female | 43.4±9.8 | TSH >4.0 mIU/L | _ | 44.23±18.13 μg/day‡ | 12 | Normal | 0.66±0.11 | 10 |
| 2011 | 0.66±0.15 | ||||||||||
| Levent | 38 | Turkey | Mixed genders | 49.8±10.0 | TSH >5.0 mIU/L | At least 2 months | 101±27.46 µg/day§ | 6† | Normal | 0.64±0.13 | 11 |
| 2010 | 0.63±0.12 | ||||||||||
| Nasmi | 25 | Iran | Mixed genders | 35.9±7.6 | TSH >4.0 mIU/L | _ | 50 μg/day | 2 | Normal | 0.56±0.09 | 11 |
| 2016 | 0.57±0.08 | ||||||||||
| Ilknur | 56 | Turkey | Mixed genders | 41.3±14.5 | TSH >4.2 mIU/L | _ | 25–50 μg/day | _ | Normal | 0.533±0.112 | 12 |
| 2014 | 0.507±0.126 | ||||||||||
| Dursun | 20 | Turkey | Female | 36±11 | TSH >4.2 mIU/L | Newly diagnosed | 25–100 μg/day | 5† | Normal | 0.65±0.09 | 12 |
| 2007 | 0.55±0.08 | ||||||||||
| Adrees | 20 | Ireland | Female | 50±9 | _ | At least 6 months | 100±30 μg/day§ | 18 | Normal | 0.82±0.2 | 10 |
| 2009 | 0.71±0.2 | ||||||||||
| Dilek | 23 | Turkey | Mixed genders | 35.2±10.7 | TSH >4.0 mIU/L | At least 6 months | _ | 6 | Normal | 0.51±0.09 | 11 |
| 2015 | 0.46±0.07 | ||||||||||