This work is licensed under a Table 1.
Overview of 16 studies included in qualitative analysis.
| Study | Sample size | Age (years)/mean | Country | TSH criteria for SCH (IU/L) | Time of study (months) | Outcomes | Mean dose of L-T4 replacement (µg/day) |
|---|---|---|---|---|---|---|---|
| ● Placebo (M/W) | ● Placebo group | ||||||
| ◊ L-T4 (M/W) | ◊ L-T4 group | ||||||
| Cooper et al. (29) | 33 (1/32) ● 16 (1/15) ◊ 17 (0/17) |
32–78/54.0 ● 32–71 ◊ 44–78 |
USA | >3.5 | 12 | TSH; T4; T3; peak TSH; prolactin; peak prolactin; weight; basal metabolic rate; water excretion; TC; TG; PEP/LVET and QKD interval | 71.2 |
| Jaeschke et al. (21) | 37 (9/28) ● 19 (3/16) ◊ 18 (6/12) |
>55/68.0 ● 68 ± 6.4 ◊ 68 ± 9.4 |
Canada | >6 | 6 | TSH; tT4; tT3; TBG; TG; TC; LDL; HDL | 68.0 |
| Meier et al. (22) | 66 (0/66) ● 33 (0/33) ◊ 33 (0/33) |
18–75/58.0 ● 57.1 ± 1.9 ◊ 57.1 ± 1.8 |
Switzerland | >5.0 | 12 | TSH; FT4; T3; TC; LDL; HDL; TC/HDL ratio; TG; ApoAI; ApoB-100; Lp(a) | 85.5 |
| Monzani et al. (15) | 20 (2/18) ● 10 (1/9) ◊ 10 (1/9) |
–/32.6 ● 29.2 ± 9.4 ◊ 34.3 ± 12.3 |
Italy | >3.6 | 12 | BMI; body surface area; SBP; DBP; MBP; HR; TSH; FT4; FT3; EDD; FS; Sthd; PWthd; LVM; CO; SVR; PEP; ET; PEP/ET; peak E; peak A; E/A; MAT; MDT; IVRT | 65.0 |
| Caraccio et al. (23)* | 49 (7/42) ● 24 (–/–) ◊ 25 (–/–) |
–/35.0 ● – ◊ – |
Italy | >3.6 | 11 | BMI; TSH; FT4; FT3; TC; HDL; LDL; TG; ApoA1; ApoB; Lp(a); TC/HDL; LDL/HDL; LDL/ApoB | 67.5 |
| Kong et al. (24) | 40 (0/40) ● 17 (0/17) ◊ 23 (0/23) |
–/– ● 45 ± 4 ◊ 53 ± 3 |
UK | 5–10 | 6 | BMI; TSH; FT4; FT3; TC; HDL; LDL; TG; ApoA; ApoB; sialic acid; mevalonic acid; % lean body weight; resting energy expenditure | – |
| Christ-Crain et al. (33) | 63 (0/63) ● 32 (0/32) ◊ 31 (0/31) |
32–79/58.0 ● – ◊ – |
Switzerland | >5.0 | 12 | TSH; FT4; T3; tHcy; CRP; Vit B12; folate; creatinine | – |
| Monzani et al. (30)* | 45 (8/37) ● 22 (–/–) ◊ 23 (–/–) |
<55/37.0 ● – ◊ – |
Italy | >3.6 | 10.5 | BMI; SBP; DBP; TSH; FT4; FT3; TC; HDL; LDL; TG; ApoA1; ApoB; Lp(a); tHcy; Vit B12; folate; maximal IMT; mean IMT | 70.0 |
| Christ-Crain et al. (35) | 63 (0/63) ● 32 (0/32) ◊ 31 (0/31) |
18–75/58 ● – ◊ – |
Switzerland | >5.0 | 12 | TSH; FT4; T3; ProANP; NT-proBNP | – |
| Iqbal et al. (25) | 64 (33/31) ● 32 (17/15) ◊ 32 (16/16) |
–/– ● 62.7 ± 12.4 ◊ 62.0 ± 11.9 |
Norway | 3.5–10 | 12 | BMI; TSH; FT4; FT3; TC; HDL; LDL; TG; ApoA1; ApoB | 97.1 |
| Razvi et al. (31) | 100 (18/82) ● 50 (8/42) ◊ 50 (10/42) |
18–80/– ● 54.2 ± 12.1 ◊ 53.5 ± 13.3 |
UK | >4.0 | 3 | TC; endothelial function (FMD); patient-reported outcomes | – |
| Teixeira et al. (27)* | 26 (–/–) ● 15 (–/–) ◊ 11 (–/–) |
–/– ● 46.6 ± 9.8 ◊ 53.8 ± 8.9 |
Brazil | >4.0 | 12 | BMI;TPO-Ab+; TSH; FT4; TC; HDL; LDL; TG; ApoA1; ApoB | – |
| Teixeira et al. (28)* | 38 (3/35) ● 20 (1/19) ◊ 18 (2/16) |
–/– ● 46.6 ± 9.9 ◊ 52.5 ± 10.1 |
Brazil | >4.0 | 6 | TC; HDL; LDL; TG; ApoA; ApoB | – |
| Mikhail et al. (26) | 120 (2/118) ● 60 (1/59) ◊ 60 (1/59) |
15–60/– ● 31.76 ± 9.89 ◊ 32.3 ± 10.2 |
Kuwait | 4–10 | 13 | TSH; TC; HDL; LDL; TG | 72.0 |
| Nagasaki et al. (32)* | 95 (0/95) ● 47 (0/47) ◊ 48 (0/48) |
–/– ● 66.0 ± 3.0 ◊ 64.2 ± 2.59 |
Japan | >4.0 | 5 | BMI; SBP; DBP; pulse pressure; pulse rate; TSH; FT4; FT3; TC; HDL; LDL; TG; CRP; BaPWV; PET/ET ratio | 25.8 |
| Martins et al. (33) | 22 (0/22) ● 13 (0/13) ◊ 9 (0/9) |
–/– ● 44.4 ± 8.9 ◊ 51.7 ± 10.2 |
Brazil | 4–12 | 12 | Left ventricular systolic and diastolic function | – |
Studies with (*) were included in meta-analysis.
ApoA, apolipoprotein A; ApoB, apolipoprotein B; BaPWV, brachial-ankle pulse wave velocity; BMI, body mass index; CO, cardiac output; DBP, diastolic blood pressure; EDD, end-diastolic diameter; ET, ejection time; FMD, brachial artery flow-mediated dilatation, an early marker of atherosclerosis; FS, fractional shortening; FT3, free triiodothyronine; FT4, free thyroxine; HDL, high-density lipoprotein; HR, heart rate; IMT, intima-media thickness; IVRT, isovolumetric relaxation time; LDL, low-density lipoprotein; Lp(a), lipoprotein(a); L-T4, levothyroxine treatment; LVM, left ventricular mass index; M, men; MAT, mitral acceleration time; MBP, mean blood pressure; MDT, mitral deceleration time; NT-proBNP, N-terminal prohormone form of brain natriuretic peptide; Peak A, late transmitral flow velocity; Peak E, early transmitral flow velocity; PEP/LVET, pre-ejection period/left ventricular ejection time; ProANP, prohormone atrial natriuretic peptide; PWthd, diastolic posterior wall thickness; QKD interval, time between the Q wave on the electrocardiogram and the detection of the last Korotkoff sound in the antecubital fossa; SBP, systolic blood pressure; Sthd, diastolic interventricular septum thickness; SVR, systemic vascular resistance; TBG, thyroxine-binding globulin; TC, total cholesterol; TG, triglycerides; tHcy, total homocysteine; TPO-Ab+, positive thyroperoxidase antibodies; TSH, thyroid-stimulating hormone; tT3, total triiodothyronine; tT4, total thyroxine; Vit B12, vitamin B12; W, women.