Earlier quoted context omitted.
But Cochrane reviews are notoriously good. They're always spoken of as the standard in meta-analysis. What's interesting here is that new research is contradicting previous findings. According to https://www.nytimes.com/2020/03/11/upshot/alcoholics-anonymo... , the weak studies they weeded out were ones that had found against AA, not in favor of it.
It is, but even if the review is done really well garbage in/garbage out.
In the last decade or so, researchers have published a number of very high-quality randomized trials and quasi-experiments. Of the 27 studies in the new review, 21 have randomized designs. Together, these flip the conclusion.
(from that NYT link)