Studies show that approxi- mately 25% of all prescribed doses are omitted by patients.
This was in 1999 more recent studies say 50% are non adherent. like the study below:
Who. Defining adherence. Who. 2003;:1–28. www.who.int/chp/knowledge/publications/adherence_report/en/?
No single intervention is totally effective for all patients and it is not yet possible to predict which individual or subgroup actually needs a given intervention.
Patients also are reluctant to admit non-adherence unless clinicians make specific efforts to monitor the degree of adherence on a regular basis.
Studies have demonstrated that MEMS is more accurate than other available methods and is therefore considered the ‘‘gold standard’’ of adherence measurement. Despite these advantages, this tool has not yet been applied widely due to its cost and other practical issues that limit its use in large studies and routine clinical practice.