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Adherence, Compliance, Persistence

Health care professionals more commonly use the term “adherence” to a medication regimen rather than “compliance”, because “adherence” better reflects the diverse reasons for patients not following treatment directions in part or in full.

Amazing: more that 500 Million prescriptions are filled each year in Canada! In the USA, over 4 Billion prescriptions are filled by retailers – this excludes hospitals and non-retail fulfillment.

More than 5 years ago, the New England Healthcare Institute revealed that medication non-adherence is the source of an estimated $290 billion in “otherwise avoidable medical spending” in the US per year. With our aging population, I contend it is even worse today!

  • $28.8 billion: What Canadians spent on prescription drugs in 2014
  • $657 million: What Quebec spent on medications in hospitals in 2013-14
  • $4 billion: What Quebec spent on publicly funded drugs in 2013-14

A recent Capgemini Consulting study indicated that the US pharmaceutical industry alone loses an estimated $188 billion annually due to medication non-adherence. This represents 59% of the $320 billion in total US pharmaceutical revenue in 2011 and 37% of the $508 billion annual potential total revenue. Looking at the global pharmaceutical market, “revenue loss is estimated to be $564 billion, or 59% of the $956 billion in total global pharmaceutical revenue in 2011 and 37% of the $1,520 billion annual potential total revenue”.

Increasing adherence rates by only 10 percentage points would translate into a $41 billion pharmaceutical revenue opportunity in the US ($124 billion globally), accompanied by improved health outcomes and decreased healthcare spending.


The extent to which patients take the medications as prescribed by their physicians. This is the preferred terminology when referring to patients taking medications. This includes dosing, frequency, specific timing, and conditions such as with or without food. It includes the concept of sticking with your medication. It encompasses compliance and persistence.

The extent to which a person’s behavior taking medication, following a diet, or making healthy lifestyle changes corresponds with agreed upon recommendations from a healthcare provider – CDC, Atlanta.


Describes the degree to which a patient correctly follows medical advice. Compliance is basically synonymous with adherence. However, compliance implies that the patient is following their doctor’s orders, while adherence assumes more of a doctor-patient partnership.

The day-to-day taking of ones medication. A patient’s passive following of provider’s orders – CDC, Atlanta.


Staying on a prescribed medication for the intended duration of treatment. Persistence is the opposite of discontinuation and is critical for successfully managing chronic conditions.

Persistence is the duration of time a patient takes medication, from initiation to discontinuation of therapy. – CDC, Atlanta.

There is evidence to suggest that non-persistence is more critical than non-compliance. For example, a patient that stops taking meds is considered 0% compliant. This includes patients that do not, or forget to refill their prescriptions.

Continuation of refills directly improves adherence.

The Effect

  • Chronically ill patients who take their medications save the health care system up to $7,800 annually per patient.
  • Every one percent improvement in adherence results in $2 billion in savings to the U.S. healthcare system and a $4 billion revenue increase to pharmaceuticals.
  • A better quality of life. A longer life!

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