To ensure some degree of blinding we chose HDRS over BDI because it was possible to perform objective blinded outcome assessment using the HDRS.
The following aspects of the quality of trial methodology were evaluated: generation of the allocation sequence, adequacy of concealment of the allocation of treatment, degree of blinding, and completeness of follow-up.
For example for the degree of blinding, if only the description on how the investigator did the blinding but no clear terms e.g. double blind were written in the articles, we categorized it as 'ambiguously stated'.
We extracted from the article specific characteristics of NI trials: degree of blinding, the method to determine the NI margin, the type of analysis, the use of a placebo arm to confirm assay sensitivity, and whether the authors discussed the constancy assumption.
One study described a partial degree of blinding, but this was limited to their neurofeedback group and did not apply to their auditory training group [ 35, 36].
Information indicative of trial quality, including methods of randomization, absence or degree of blinding, completeness of patient follow-up, and whether statistical analyses were performed by intent-to-treat were also extracted from each trial report.
Of importance, this was the only study in which the allocation sequence was adequately generated, allocation concealment was appropriate, some degree of blinding occurred, and appropriate intention to treat analysis was utilized.
