Study designs of evaluations included in the review
Double-blind placebo-controlled trials (RCTs) were eligible for inclusion. Studies with less than five patients per treatment arm were excluded. The duration of follow-up ranged from 21 to 28 days.
Specific interventions included in the review
Studies that compared antidepressants plus placebo with antidepressants plus thyroid hormone were eligible for inclusion. Treatment with thyroid hormone had to start less than 6 days after the initiation of antidepressant treatment. All of the included studies used triiodothyronine (T3) as the thyroid hormone; the doses ranged from 20 to 62.5 microg/day (most studies used 20 to 25 microg). The included studies used either imipramine (dose of 150 to 200 mg/day in all but one study) or amitriptyline (100 mg) as the antidepressant. Thyroid hormone was added to the antidepressant treatment from day 1 to day 5 of treatment.
Participants included in the review
Studies of relatively untreated patients were eligible for inclusion. Studies of patients who failed to respond to standard antidepressant treatment were excluded. The proportion of females ranged from 53 to 100% across the studies. The studies included euthyroid patients, but not all studies assessed the thyroid status of the participants.
Outcomes assessed in the review
Studies that assessed the rate of recovery using a standardised rating scale for depression were eligible for inclusion. The 'acceleration' outcome was measured as a statistically-significant difference between thyroid hormone and placebo in the time to a change in depression. The included studies all assessed depression using the Hamilton Depression Rating Scale.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.