Adding the clinical framing, because it changes how the question reads. The honest answer is that the effect is real, the magnitude is contested, and the individual variation is larger than either. Those three things can all be true at once, and most arguments here are two people holding different parts of that.

raj_cambridge said:

If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way.

Coming at raj_cambridge’s question from a different direction. It helps to ask what evidence would change your mind before you look at any. If nothing would, the discussion is not about evidence, and it is better to say so early than to spend nine posts discovering it.

One concrete data point for the thread. Say what you would expect to see if you were wrong, before you look. It is a small discipline and it changes what you notice.

A narrower follow-up, since the general answer is now clear:

Was that from a primary source or from a summary of one?

Moderator note: the sourcing question belongs in the vendor section and has been split out.