According to an article by the Centers for Disease Control and Prevention, approximately one in five new prescriptions are never filled, and among those filled, approximately 50% are taken incorrectly, particularly with regard to timing, dosage, frequency, and duration.
Adherence to prescribed medications is associated with improved clinical outcomes for chronic disease management and reduced mortality from chronic conditions. Conversely, nonadherence is associated with higher rates of hospital admissions, suboptimal health outcomes, increased morbidity and mortality, and increased healthcare costs.
An article in Mayo Clinic Proceedings listed several factors that contribute to poor medication adherence. Some are patient-related, such as low health literacy, some are physician-related, such as the prescription of complex drug regimens, and some are related to health care systems, such as office visit time limitations.
The Department of Health and Human Services suggests providers use the SIMPLE method when prescribing medication: Simplify the regimen, Impart knowledge, Modify beliefs and Behavior, Provide communication and trust, Leave the bias and Evaluate adherence. If patients forget to ask their doctor, they can ask their pharmacist about how to take their medications, what to do if they miss a dose and how to organize a pill box.
Resources:
https://www.cdc.gov/mmwr/volumes/66/wr/mm6645a2.htm
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3068890/
https://millionhearts.hhs.gov/files/TipSheet_HCP_MedAdherence.pdf
http://www.pharmacytimes.com/news/ask-the-right-questions-to-improve-medication-adherence