I recently came across a paper that uses the McNemar test to evaluate the effectiveness of an intervention to improve adherence to treatment. The study used a pre/post test design whereby the adherence behaviour for both the control and intervention group was measured using the same instrument and expressed as continuous data. It then compares the relative improvement (post / pre) between the two groups. I've never seen the McNemar test used for this before, but am not sufficiently familiar with statistics. Is it really an appropriate method? Wouldn't a (paired) t-test or something like that make more sense?
Within either the treatment or the control group the McNemar test seems perfectly appropriate to test marginal homogeneity of the pre/post vs adherent/non-adherent contingency table - it's a matched-pair design for dichotomous variables. I can't see how you'd use it to compare treatments vs controls, as they're unmatched, presumably. It's not clear from your description what tests were actually carried out in this study.