Health literacy and adherence: facts and figures

Facts and figures on adherence to medical plans in the ageing population

Definition of adherence

Adherence can be defined as the extent to which a person’s behaviour such as following a diet, taking medication, or making lifestyle changes, are in agreement with recommendations from a health professional. Sometimes terms like compliance or concordance are used instead of adherence, to underline the necessary process of communication and negotiation between the client and healthcare professionals.

People of 65 years and older in Western countries consume about one-third of all medicines in the world. On average, only half of older people in Europe, who are undergoing long-term treatment for chronic diseases, take medication as prescribed. People may not take the prescribed medicines at all, or may take them at the wrong time or in the wrong doses. Also, physical exercise, diets or other preventive activities are often not implemented as suggested by health professionals. The longer people have to take medicines or therapies, the poorer the adherence becomes. This becomes problematic for long-term treatment of cardio-vascular diseases, lung diseases or diabetes.

Effects of treatment are often not what prescribing physicians expect

Poor adherence to medical plans and medication is a public health concern: the effects of treatment are not what prescribing physicians expect. People may live longer, but in poor health and can only participate to a limited extent in society. Moreover, it reduces the cost- effectiveness of medicines and health services. Indeed, billions of euros are wasted on ineffective treatment in Europe.

Old age alone is not a reason for poor adherence. But as older people often suffer from one or more chronic disease, the quantities of used medicines are significant.

Other factors influencing adherence for older people are:

  • There are more side effects and interactions.
  • The body may respond differently to medication than in younger people.
  • The burden of taking many medicines is often mentioned as cause of poor adherence.
  • Lack of social support
  • Living alone.
  • Forgetfulness (cognitive decline) are some other factors influencing adherence.These factors are found more in the ageing population. Sometimes financial barriers play a role, when governments or insurance companies limit reimbursements of prescriptions or do not pay for physiotherapy or special dietary needs. There is also a group of persons who deliberately decide not to take medicines as prescribed, because of side effects, choosing other therapies, or other priorities in life.

Adherence is an important and complicated public health issue because of the wide range of influencing factors.

Health literacy is a factor associated with poor adherence to medical plans and medication. When people have difficulties reading, writing and calculating it is obvious that taking medicines and implementing diets are challenges. But there are also people who have difficulties communicating their problems concerned with the taking of medicines or following therapies. Health professionals play an important role in adherence: poor explanation, insufficient follow up and poor co-ordination among prescribers contribute to poor adherence. There is also a health systems factor, for example, when the exchange of information between primary healthcare, hospitals and public pharmacies is poor, leading to contradictory treatments or wrong prescriptions. Health literacy is one of the issues to be addressed in order to improve adherence.


  • EIP-AHA: Action Plan on Prescription and Adherence to Treatment, European Innovation Partnership on Active and Healthy Ageing, November 2012 Download PDF here
  • Geboers BJ et al. The association of health literacy with adherence in older adults, and its role in interventions: a systematic meta-review. BMC Public Health (2015) 15:903 DOI 10.1186/s12889-015-2251-y