Percent of doses of a drug taken as prescribed while patient is actively taking drug.
"An estimated half of those for whom treatment regimens are prescribed do not follow them as directed. Until recently, this was termed "non-compliance", which was sometimes regarded as meaning that not following the directions for treatment was due to irrational behavior or willful ignoring of instructions. Today, health care professionals more commonly use the terms "adherence" to or "concordance" with a regimen rather than "compliance", because these terms are thought to more accurately reflect the diverse reasons for patients not following treatment directions in part or in full. However, the preferred terminology remains a matter of debate. In some cases, concordance is used to refer specifically to patient adherence to a treatment regimen that is designed collaboratively by the patient and physician, to differentiate it from adherence to a physician only prescribed treatment regimen.Despite the ongoing debate, adherence is the preferred term for the World Health Organization, The American Pharmacists Association, and the U.S. National Institutes of Health Adherence Research Network." -- Source: Wikipedoia