Table 2.
Quality assessment of the included randomized controlled trials.
| Reference | Selection Bias (Randomization and allocation concealment) | Risk of bias due to deviation from intended interventions (e.g., adherence) | Risk of bias due to missing outcome data | Risk of bias in measurement of levo-triiodothyronine (L-T3) preference outcome with explanation | Selective outcome reporting |
|---|---|---|---|---|---|
| Appelhof et al. (14) | Low | Some concerns* | Low | Some concernsμ Explanation: Subjective appreciation of L-T3 compared to pre-trial L-T4 was rated by the participants on a 5-point scale (much better, somewhat better, the same, somewhat worse, or much worse), and those who indicated much or somewhat better were categorized as preferring L-T3. Unclear if validated scale. |
Low |
| Bunevicius et al. (15) | Some concerns* | Some concerns* | Low | Some concernsμ Explanation: At the end of the trial, participants asked which treatment was preferred. Unclear if standardized instrument or wording or if what response options may have been provided. |
Low |
| Bunevicius et al. (16) | Some concerns* | Some concerns* | High (23% loss randomized participants) | Some concernsμ Explanation: At the end of the trial, participants asked which treatment was preferred. Unclear if standardized instrument or wording or if what response options may have been provided. |
Low |
| Escobar-Morreale et al. (17) | Low | Low | Low | Some concernsμ Explanation: At the end of the trial, participants asked which treatment was preferred. Unclear if standardized instrument or wording or if what response options may have been provided. |
Low |
| Nygaard et al. (18) | Some concerns† | Some concerns* | Some concerns (13% loss randomized participants) | Some concernsμ Explanation: At the end of the trial, participants asked which treatment was preferred. Unclear if standardized instrument or wording or if what response options may have been provided. |
Low |
| Rodriguez et al. (19) | Low | Some concerns* | Some concerns (10% loss randomized participants) | Some concernsμ Explanation: At the end of the trial, participants asked which treatment was preferred. Unclear if standardized instrument or wording or if what response options may have been provided. |
Low |
| Walsh et al. (20) | Some concerns‡ | Low | Low | Some concernsμ Explanation: At the end of the trial, participants asked which treatment was preferred. Unclear if standardized instrument or wording or if what response options may have been provided. |
Low |
*
Insufficient detail reported in the manuscript.
†
The levothyroxine component of combination therapy was open label for dose adjustment.
‡
Sealed envelopes were used but there was no report of whether these were opaque (to ensure that the treatment allocation was not visible through the envelope).
μ
Some concerns, if there was no validated questionnaire outcome measure for treatment preference.