TABLE 1.
Characteristics of the included studies.
| Study | Types of study | Country | Sample size | Age (year) | TSH (normal range; mIU/L) | Baseline TSH (median/mean, LT4/control) | Defintion of TPOAb positivity (IU/ml) | ||
|---|---|---|---|---|---|---|---|---|---|
| LT4 | Control | LT4 | Control | ||||||
| Negro 2005 | RCT | Italy | 36 | 36 | 29.2 ± 4.0 | 30.1 ± 5.0 | 0.27–4.2 | 1.9/1.7 mIU/L | >100 |
| Negro 2006 | RCT | Italy | 57 | 58 | 30.0 ± 5.0 | 30.0 ± 6.0 | 0.27–4.2 | 1.6/1.7 mIU/L | >100 |
| Negro 2016 | RCT | Italy | 198 | 195 | 28.9 ± 5.2 | 29.9 ± 5.1 | 0.5–2.5 | 1.4/1.4 mIU/L | >16 |
| Nazarpour 2017 | RCT | Iran | 18 | 24 | 26.6 ± 5.8 | 27.0 ± 4.7 | 0.1–4 | 3.7/3.2 mIU/L | >50 |
| Wang 2017 | RCT | China | 300 | 300 | 31.3 ± 3.9 | 31.7 ± 3.8 | 0.5–4.78 | 2.9/2.1 mIU/L | ≥60 |
| Dhillon-Smith 2019 | RCT | United Kingdom | 476 | 476 | 32.5 ± 4.9 | 32.7 ± 4.9 | 0.44–3.63 | 2.1/2.0 mIU/L | >99% concordance in the U.K. NEQAS IIA |
| Revelli 2009 | Cohort study | Italy | 55 | 38 | 35.1 ± 4.1 | 37.0 ± 3.5 | NR | 2.1/2.0 mIU/L | ≥35 |
| Lepoutre 2012 | Cohort study | Belgium | 49 | 47 | 31.5 ± 5.5 | 32.5 ± 5.3 | 0.2–3.5 | NR mIU/L | ≥9 |
| Mohammad 2012 | Cohort study | Iran | 39 | 6 | NR | NR | NR | NR mIU/L | >40 |
| Alessandro 2021 | Cohort study | Italy | 227 | 230 | 36.3 ± 4.4 | 34.7 ± 4.4 | 0.4–2.5 | 1.7/1.4 mIU/L | unknown |
| Tsunemi A 2021 | Cohort study | Japan | 25 | 11 | 36.1 ± 5.3 | 36.8 ± 5.0 | 2.5-URL | 3.4/3.3 mIU/L | ≥16 |
RCT, randomized controlled trial; LT4, levothyroxine; TSH, thyroid-stimulating hormone; NR, not reported; URL, upper reference limit.