Download PDF version of web site
Increase Font Size Decrease Font Size

Age by itself is not a determining factor in medication nonadherence. Rather, there are many factors that may combine to render older persons less able to adhere to their medication regimens. However, there is evidence to suggest that with the proper motivation, education, and support, older persons can overcome many barriers to medication adherence (US Department of Health and Human Services, 1990).


Figure 2

Source: World Health Organization, 2003

Adherence is a multidimensional phenomenon determined by the interplay of five sets of factors, termed "dimensions" by the World Health Organization (Figure 2):

  1. Social/economic factors
  2. Provider-patient/health care system factors
  3. Condition-related factors
  4. Therapy-related factors
  5. Patient-related factors

Patient-related factors are just one determinant of adherence behavior (World Health Organization, 2003). The common belief that a person is solely responsible for taking their medications often reflects a misunderstanding of how other factors affect people's medication-taking behavior and their capacity to adhere to treatment regimens. Factors associated with each dimension are listed in Table 2.

It is clear that adherence is a complex behavioral process strongly influenced by the environments in which people live, health care providers practice, and health care systems deliver care. Adherence is related to people's knowledge and beliefs about their illness, motivation to manage it, confidence in their ability to engage in illness-management behaviors, and expectations regarding the outcome of treatment and the consequences of poor adherence (World Health Organization, 2003).

It is important to recognize that a person may have multiple risk factors for medication nonadherence. Also, factors that can influence a person's medication-taking behavior may change over time. Therefore, it is important to continually assess a person's adherence throughout the course of therapy. In addition, because there is usually no single reason for medication nonadherence, there can be no "one size fits all" approach to improving adherence.

Many of the interventions used to improve adherence focus on providing education to increase knowledge; simplifying the medication regimen (fewer drugs or fewer doses); or making it easier to remember (adherence aids, refill reminders). However, simplifying a dosage regimen is unlikely to affect a person who does not believe that taking medications is important or that the therapy will improve his or her health, and the available evidence shows that knowledge alone is not enough for creating or maintaining good adherence habits (World Health Organization, 2003).

Based on published studies, it is evident that single interventions are less successful than multiple, long-term interventions in affecting adherence. Studies have shown that the most successful interventions have some follow-up component and address the underlying reason(s) for nonadherence (Krueger et al., 2003). Comprehensive interventions should address a variety of issues, including knowledge, motivation, social support, and individualizing therapy based on a person's concerns and needs (Krueger et al., 2003; McDonald et al., 2002).

The ideal time to initiate adherence interventions is when therapy first begins. Interventions that are initiated early in the course of therapy can support older persons through a period when they are most likely to have questions or to experience side effects from therapy.


Limited English language proficiency
Low health literacy
Lack of family or social support network
Unstable living conditions; homelessness
Burdensome schedule
Limited access to health care facilities
Lack of health care insurance
Inability or difficulty accessing pharmacy
Medication cost
Cultural and lay beliefs about illness and treatment
Elder abuse
Provider-patient relationship
Provider communication skills (contributing to lack of patient knowledge or understanding of the treatment regimen)
Disparity between the health beliefs of the health care provider and those of the patient
Lack of positive reinforcement from the health care provider
Weak capacity of the system to educate patients and provide follow-up
Lack of knowledge on adherence and of effective interventions for improving it
Patient information materials written at too high literacy level
Restricted formularies; changing medications covered on formularies
High drug costs, copayments, or both
Poor access or missed appointments
Long wait times
Lack of continuity of care
Chronic conditions
Lack of symptoms
Severity of symptoms
Psychotic disorders
Mental retardation/developmental disability
Complexity of medication regimen (number of daily doses; number of concurrent medications)
Treatment requires mastery of certain techniques (injections, inhalers)
Duration of therapy
Frequent changes in medication regimen
Lack of immediate benefit of therapy
Medications with social stigma attached to use
Actual or perceived unpleasant side effects
Treatment interferes with lifestyle or requires significant behavioral changes
Physical Factors
Visual impairment
Hearing impairment
Cognitive impairment
Impaired mobility or dexterity
Swallowing problems
Psychological/Behavioral Factors
Knowledge about disease
Perceived risk/susceptibility to disease
Understanding reason medication is needed
Expectations or attitudes toward treatment
Perceived benefit of treatment
Confidence in ability to follow treatment regimen
Fear of possible adverse effects
Fear of dependence
Feeling stigmatized by the disease
Frustration with health care providers
Psychosocial stress, anxiety, anger
Alcohol or substance abuse

Sources: Miller et al., 1997; Nichols-English and Poirier, 2000; Vermiere et al., 2001;
World Health Organization, 2003; Krueger et al., 2005; Osterberg and Blaschke, 2005