Medication Adherence

Person Characteristics

Several characteristics of the person prescribed a medication may affect his or her adherence to its use. Cognitive function, mood, age, socioeconomic status, and cultural background are all related to medication adherence. Poorer cognitive function has been related to lower levels of adherence, and more complex cognitive functions such as executive abilities may be related to more complex adherence behaviors. Depression has a negative effect on adherence. Although increasing age is commonly thought to be associated with poorer adherence, several studies have shown that older adults actually have better adherence than their younger counterparts. African Americans have been shown to have poorer adherence to some medications even after controlling for factors such as access to care and socioeconomic status.

Person Beliefs

Individuals' beliefs about the medication, including the extent to which it is useful for the condition for which it is given, have important effects on adherence. Several theories have been proposed to explain the relation between beliefs and behavior, including Janz and Becker's health belief model and Ajzen's theory of planned behavior as well as others. In addition to beliefs about effectiveness, beliefs about the seriousness of the treated condition can affect adherence. Adherence to a medication believed to be ineffective or prescribed for a condition that is viewed as not very serious (e.g., a medication for mild insomnia) is likely to be lower than for an effective medication given for a life-threatening condition.

Treatment Characteristics

Characteristics of the treatment regimen may also affect adherence. Regimen complexity (number of medications, number of doses, whether doses must be taken a certain time before meals or should be taken with food) plays a role in adherence. In some health conditions, such as HIV-related diseases, regimen complexity may interact with cognitive status. The presence or absence and severity of adverse effects (side effects) have an important negative impact on medication adherence.

Social Environment

Beliefs of caregivers, significant others, or family members about the medication's effectiveness and the condition for which it is prescribed are likely to affect adherence. Caregiver or family beliefs may be especially important for conditions that affect cognitive or functional status and thus require external information or caregiver interventions (e.g., Alzheimer's disease, congestive heart failure, HIV-related dementia).

External Supports

Individuals' medication adherence is a complex behavior that must occur over long periods of time. Maintenance of the behavior consistently over such intervals can be supported by mechanical devices such as pill boxes that can be filled a week or month at a time and thus provide passive prompts to the treated individual on a daily basis. Active prompts can be provided via alarm clock-based timers, computer-based automated reminding via home telephones or pagers, and in-home checks and reminders by home healthcare workers.

...