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Non-adherence and Non-persistence

‘Drugs do not work in patients who do not take them,’ said former surgeon general C. Everett Koop. Unfortunately, the choice not to adhere to a therapy and/or to discontinue it altogether can have significant consequences for its effectiveness and safety. If non-adherence and non-persistence are caused by therapy characteristics itself, this might even mean that both regulatory and payer acceptance might be affected.

A new Cytel webinar series convened by Dr. Sabrina Mueller and Dr. Thomas Wilke, will examine the phenomena of non-adherence and non-persistence. The extent to this will be examined across three sessions, the first of which underscores the definition and importance of non-adherence and non-persistence.


The first of this three-part series will look at the conceptual understanding of non-adherence and non-persistence. By way of a quick review:

  • Non-adherence: Adherence refers to “the quality of therapy implementation during phases of therapy implementation.” By extension non-adherence is the situation of faulty implementation of therapy, which can in turn affect the real-world effectiveness and safety of a therapy and, naturally, overall healthcare cost.
  • Non-persistence: Persistence refers to ‘the duration of the therapy’. Non-persistence is therefore a situation where the therapy has been discontinued.

Not all Non-Adherence is the Same

According to Cytel scientists Sabrina Mueller and Thomas Wilke, we must take time to classify different types of non-adherence to ensure that the effects on evidence collection is adequately understood.

Patterns of non-adherence might be different in various situations: patients who take medication erratically (e.g., forget to take it once or twice a week) are in a different situation from patients who on purpose planned drug holidays, etc. Different forms of non-adherence might have different causes and might affect therapy success in different ways, so that an RWE expert must ensure that these differences are accounted for when doing adherence-related studies.

Not all Non-Persistence is the Same

Similar to the above, not all non-persistence is the same. Sometimes it is induced early after the first or second prescriptions, other patients discontinue their (originally lifelong) medication therapy quite late. Whereas non-adherence is always a decision made by the patient, therapy discontinuation might be based on patients’ or physicians’ decisions.


The new webinar will highlight a number of instances where the safety and effectiveness of a therapy were evaluated as less than they actually ought to have been, due to non-adherence/early non-persistence. As the safety and effectiveness of a therapy link directly to its cost and the likelihood that clinicians will use it, this has extended consequences for sponsors.

Register for the Webinar to learn more:



About the Author of Blog: 


Dr. Esha Senchaudhuri is a research and communications specialist, committed to helping scholars and scientists translate their research findings to public and private sector executives. At Cytel Esha leads content strategy and content production across the company's five business units. She received a doctorate from the London School of Economics in philosophy, and is a former early-career policy fellow of the American Academy of Arts and Sciences. She has taught medical ethics at the Harvard School of Public Health (TH Chan School), and sits on the Steering Committee of the Society for Women in Philosophy's Eastern Division, which is responsible for awarding the Distinguished Woman in Philosophy Award. 


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