Is 80% adherence evidence-based? The review says not as a universal rule

Is 80% medication adherence really a universal cutoff? The review says that number came from an early empirical definition in antihypertensive care, where taking at least 80% was treated as sufficient[[cite:1]].

But the authors do not treat 80% as a proven standard. They say they could not reject or confirm the validity of the historical 80% threshold, and that it was clearly questioned as a general standard[[cite:2]].

Why the uncertainty? The review says the needed adherence cutoff can depend on the disease, medication, and patient characteristics, because those factors can change what level still produces a satisfactory outcome[[cite:3]].

The included studies also spanned different chronic diseases and outcomes, including event-free episodes, hospitalization, cortisone use, reported symptoms, and lipid reduction[[cite:4]].

A big limitation is measurement heterogeneity. Because adherence was calculated in different ways, the authors could not compare studies quantitatively or standardize adherence rates across them[[cite:5]][[cite:6]].