Adherence is an important topic in pharmaceutical care. Studies suggest that only 50-70% of medicines prescribed for long-term conditions are taken as intended. One of the aims of the pharmacists' activities is to improve the patients' outcomes, and thus adherence is an important topic to discuss. This is especially important for medicines that are used to treat chronic diseases (cardiovascular, diabetes), medicines of which the effects can usually not be noticed (statins, antihypertensives) and for medicines with a small therapeutic window (digoxin, lithium, thyroid hormones, anti-epileptics, insulin). But, in view of the development of resistance, adherence is also important for antibiotics and antiviral medication. Optimal adherence usually stands for optimal outcomes of therapy but certainly not always.
The concept of adherence can be divided into three, some say four, phases (see Vrijens et al 2012) (free):
- Initiation (the start, some people do not start the therapy that has been advised to them)
- Implementation (a starting phase of correct use, some patients use their medicines not in accordance with the therapeutic advice)
- Persistence (once started, some patients do not keep on taking their medicines and stop their therapy deliberately)
- Discontinuation (deliberate stopping of therapy, initiated by patient or professional)
Others have just split the concept into two modes: adherence and persistence. (see Raebel et al 2013) (free)
Different methods have been developed to study the patients' adherence. Some of these methods have also been shown to be useful in daily pharmacy practice.
- Blood levels – PK/PD
- Biological markers
- Individually chipped medicines
- Questionnaires-structured interviews
- Patient report/Diaries
- Pill counts
- Pharmacy dispensing data
- Assessing clinical response
- Electronic tools (smart packs)
There are many causes of non˗adherence but they fall into two overlapping categories: intentional and unintentional. Unintentional non˗adherence occurs when the patient wants to follow the agreed treatment but is prevented from doing so by barriers seemingly beyond their control. One of the guidance documents of NICE: 'Medicines adherence: involving patients in decisions about prescribed medicines and supporting adherence' (2009) (free) further elaborates this concept, as does an illustrative article by Elliott, with the title 'Non-adherence to medicines, not solved bur solvable' (2009) (free at Google Scholar).
- Reminders (including apps for Iphone and android)
- Dispensing in week dispensing systems/boxes , blisters
- Containers with alarms (see review of Boenie et al.) (free)
- Phone, email or SMS services,
- IT-tools and websites
In practice several techniques combined may be effective. See the presentation of van Mil about the 2015 situation in the Netherlands as an example.
The term 'adherence'is relatively new. In former days, the term 'compliance' was used, because it was assumed that patients must be compliant to the advices of the medical profession, a rather paternalistic approach that did not do justice to the freedom of the patient to choose and influence their own treatment.
In the world of pharmacy in Europe, there is one organisation that annually discusses patient adherence: Espacomp. See their website.
Because adherence is also very important for anticoagulants, and pharmacist can have a positive role, this topic is under study in the iPACT working groups of the DRM-Foundation.
In 2011, in the USA, medication adherence leaders organized a 2-day think tank. The leaders called the group the 'Medication Adherence Alliance'. The Alliance is still active today. More information about this think tank, their objectives and findings can be found in: Zullig LL, Granger BB, Bosworth HB. A renewed Medication Adherence Alliance call to action: harnessing momentum to address medication nonadherence in the United States. Patient Preference and Adherence 2016:10; 1189–1195. (free)