Table 1.
Characteristics of the Selected Studies
| Country | Author, year (ref.) | Study type | Number of patients (female/male) | Age (mean) years | LT4 dose | PPI dose | TSH mU/l before PPI | TSH mU/l after PPI | Follow-up | Quality |
|---|---|---|---|---|---|---|---|---|---|---|
| Italy | Centanni, 200625 | Interventional, non-randomized controlled study | 10 (F) | NS |
1.58 μg/kg/day tablets (Eutirox®) Was taken at least 1 h before breakfast |
omeprazole 40 mg/day |
0.1 | 1.70 | 6 months | Low risk of bias* |
| UK | Irving, 201526 | Observational, retrospective | 1491 | 58.1 |
Tablets. For at least 6 months |
omeprazole, pantoprazole, lansoprazole esomeprazole rabeprazole | 1.51 ± 2.64 | 1.69 ± 2.83 | 6 months | Good quality** |
| USA | Sachmechi, 200727 | Observational, retrospective |
37 (30 F, 7 M) |
59 ± 7.5 |
25 to 200 μg/day (mean 82.8 ± 40.3) (tablets) For at least 6 months |
lansoprazole 30 mg/day | 2.34 ± 1.3 | 3.0 ± 2.2 | 2–6 months | Good quality** |
| Brazil | Abi-Abib, 2014,31 | Interventional, uncontrolled before–after study |
All: 19 Group omeprazole 20 mg: 10 (8 F 2 M). Group omeprazole 40 mg: 9 (8 F, 1 M). |
Group 1 (omeprazole 20 mg): 54.6 ± 10.9 Group 2 (omeprazole 40 mg): 50.6 ± 10.2 |
Tablets (Puran T4®) for at least 1 year. Was taken at least 30 min before PPI, and PPI 15 min before breakfast |
Group 1: omeprazole 20 mg (Neoprazol®) Group 2: omeprazole 40 mg (Neoprazol®) |
All: 2.48 ± 1.12. Group omeprazole 20 mg: 2.45 ± 0.98. Group omeprazole 40 mg: 2.51 ± 1.33. |
All: 2.76 ± 1.75. Group omeprazole 20 mg: 2.80 ± 1.80. Group omeprazole 40 mg: 2.71 ± 1.79. |
3 months | Low risk of bias* |
| Italy | Trifiró. 2015,28 | Quasi-experimental pre–post analysis | 3787 | 54.6 ± 14.47 | NS | NS | NS | TSH levels increased with the concomitant use of PPI (adjusted IRR: 1.02; 95% CI: 1.01–1.03) | 15 days | Low risk of bias* |
| Italy | Saraceno, 201237 | Interventional non-randomized crossover study |
All: 15 (12 F, 3 M). Group 1 (REP): 6 Group 2 (SUP): 9 |
NS | Tablets and then oral solution (Tirosint®) |
omeprazole (n = 7) pantoprazole (n = 5) lansoprazole (n = 3) |
NS |
Group 1 (REP) LT4 tablet and PPI: 2.77 ± 2.05. LT4 solution and PPI: 1.63 ± 0.66. Group 2 (SUP) LT4 tablet and PPI: 1.15 ± 1.85. LT4 solution and PPI: 0.12 ± 0.12 |
2 months after switch | Moderate risk of bias* |
| Italy | Vita, 201438 | Interventional non-randomized study |
All: 24 (18 F, 6 M) Group 1 (REP): 14 (11 F, 3 M) Group 2 (SUP): 10 (7 F, 3 M) |
All: 56.2 ± 14.5 Group 1: 63.3 ± 11.2 Group 2: 46.7 ± 13.2 |
Tablets and then oral solution (Tirosint®) 1.5 μg/kg/day ± 0.4. Was taken 30 min before PPI and 60 min before breakfast |
omeprazole (n = 9) pantoprazole (n = 7) lansoprazole (n = 6) esomeprazole (n = 2) |
NS |
Group 1 (REP) LT4 tablet and PPI: 5.4 ± 4.3. LT4 solution and PPI: 1.7 ± 1.0. Group 2 (SUP) LT4 tablet and PPI: 2.1 ± 2.7 LT4 solution and PPI: 0.1 ± 0.3 |
Group 1: 20.0 ± 7.5 weeks Group 2: 28.8 ± 15.2 weeks |
Low risk of bias* |
*The Risk Of Bias In Non-randomized Studies – of Interventions (ROBINS-I)30 tool was used to evaluate seven bias domains as low, moderate, or serious risk of bias
**Assessed by the Newcastle–Ottawa Scale29 for observational studies with a score of 8/9 (maximum of 9 points). Score > 6 points is considered to be of high quality. NS not specified, TSH thyroid-stimulating hormone, LT4 levothyroxine, PPI proton pump inhibitor, NOS Newcastle–Ottawa Scale, F female, M male, REP replacement therapy, SUP suppressive therapy, IRR incidence rate ratio