Adherence or Compliance Behavior

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Hippocrates once wrote that patients often lied about taking their medicine. Adherence to medication was a big problem then, and still is today. Indeed, one of the most challenging problems facing physicians is their ability to improve patient compliance with prescribed regimens. Estimates for nonadherence across diverse areas of treatment range from a low of 4 percent to a high of 92 percent, with an average ranging from 30 to 60 percent. Adherence rates for preventive health behaviors are generally lower than those behaviors requiring long-term management or control of a chronic condition. For example, adherence for patients with ischemic heart disease is 74 percent, while adherence to a prescribed wear-and-care regimen of disposable contact lenses is 31 percent, despite the risk of complications related to extended wear lenses.

Given that many diseases are preventable, curable, or at least treatable, patient adherence is often a crucial step toward improving treatment status and achieving good health. The diagnosis, the carefully weighted treatment plan, and the expanded time and effort in patient education all become wasted efforts if a patient does not adhere to the prescriptions and proscriptions recommended by a health care provider. Gerald H. Friedland and Ann Williams identified adherence as the "greatest barrier to overall therapeutic success" (1999, p. S64).


Adherence became a topic of considerable research by multidisciplinary teams beginning in the 1970s, when studies showed that as many as 50 percent of patients diagnosed with hypertension were not taking sufficient amounts of their antihypertensive medication, and that nonadherence was common, particularly with long-term treatments for conditions such as diabetes, asthma, hypertension, and HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome).

What is adherence and why do many patients fail to comply with a medication regimen? Adherence to medical recommendations has been defined as the extent to which a person's behavior coincides with medical or health advice, such as taking medication regularly, returning to a doctor's office for follow-up appointments, and observing preventive and healthful lifestyle changes. Despite the positive health benefits that adherence engenders, however, many patients fail to adhere or comply to medical advice for a variety of reasons.

With the advent of complex treatment regimens for HIV infection (often characterized as among the most complicated long-term regimens in history), and the risk of drug resistance resulting from missed doses, research on adherence has centered on who is and is not likely to be adherent, how adherent one needs to be in order to prevent drug resistance, and what strategies are likely to work for improving adherence. Controversial ethical issues have emerged regarding the provision of complex treatments to HIV/AIDS patients who may seem unable to adhere to them, and possibly contributing to the passing of resistant HIV strains to others. Drug formulation and regimens that allow for simplified dosing have become a research priority, and novel devices and techniques have been developed that can assist patients in adhering to medication regimens.


Studies of nonadherence indicate that from 10 to 90 percent of patients do not fully follow their doctor's orders. Most researchers agree that at least half of all patients do not take their prescribed drugs correctly. Adherence to lifestyle regimens such as diet and exercise is probably far worse. It is difficult to predict who will adhere to a given course of medication and who will not. According to most published studies, adherence does not correlate with age, sex, race, occupation, education, income level, or socioeconomic status. Even homelessness is not an indicator of a low likelihood of adherence in all patients; given appropriate access to treatment, encouragement, and rewards, homeless individuals can be as adherent as any group. In fact, about the only good indicator of future adherence is how a patient has behaved in the past.

The five most common types of nonadherence with medication are: 1) failing to have a prescription filled, (2) taking an incomplete dose,(3) taking the medication at the wrong time, (4) forgetting to take one or more medications, and(5) stopping the medication. Each of these behaviors requires individual consideration in order to formulate strategies to enhance patient compliance.

Failure to obtain a medication is especially problematic in patients with asymptomatic conditions, such as hypertension or latent tuberculosis. The health care provider must reinforce the importance of taking medications daily, even if one does not "feel sick," to prevent the effects of target organ damage or developing resistant strains of the infection. Once a patient obtains a medication, the two most common nonadherence behaviors include omitting one or more doses or taking a medication at the wrong time. This behavior has been termed "partial compliance."

While partial compliance is intentional in a minority of patients, in others, such as the elderly, it is often unintentional. Forgetting to take a medication is the most common cause of taking insufficient medication in this population and is attributed to such factors as using more than one pharmacy, seeing different physicians, confusion regarding the regimen, inaccurately labeled containers, and the inability to open childproof containers. The health care provider must make special efforts during the patient visit to address these potential concerns related to nonadherence.


Adherence to medical recommendations is a multifactorial behavior and requires a multifactorial response. Therefore, strategies to encourage adherence must not only address intrapsychic factors such as knowledge of the regimen, belief in benefits of treatment, subjective norms, and attitudes toward medication-taking behavior, but also environmental and social factors such as the interpersonal relationship between the provider and the patient and social support from family members and friends.

Educational approaches to enhancing nonadherence generally begin with providing the patient with a general understanding of the importance of the medical recommendations. Although information and increased knowledge is necessary for the behavior to take place, it is often insufficient to sustain or reinforce the behavior over time. Health care providers who employ a combination of verbal and written instruction often see enhanced levels of adherence among their patients. This is especially true for disadvantaged populations and for individuals with low literacy skills, who often benefit from tailored educational messages regarding the duration of treatment, dosage, frequency, or purpose of medication. Studies have also demonstrated that personalized follow-up on adherence through the pharmacy results in increased rates of adherence. Considerable interest among community pharmacists in expanding their role to include more prevention is evident in recent surveys. Changing office visit appointment schedules from a block approach to individualized appointments also results in higher rates of kept appointments and provides greater opportunities for behavioral reinforcement by the health care provider.

Medication assessment techniques such as electronic medication monitors indicate that approximately 50 to 60 percent of patients achieve near-optimal or excellent adherence. This result is similar to other measurement strategies utilizing self-reported measures. A simple self-reported medication-taking measure is described in D. E. Morisky et al. (1986), consisting of four questions, such as "Do you ever have problems remembering to take your medication?" or "Do you sometimes forget to take your medication?" Individuals who score high on this assessment (i.e., answer each question with a "no") are significantly more likely to have their blood pressure under control compared to individuals who scored lower. This simple adherence assessment allows the health practitioner to assess the various determinants of medication-taking behavior, thereby providing opportunities for behavioral reinforcement, such as enlisting social support (informational, emotional, and tangible) from provider staff and family members.

Many behavioral strategies have been found to be successful in increasing adherence with medications. Multicomponent strategies are much more effective than single-component approaches. Some of the most effective behavioral strategies include tailoring the medical regimen to the patient's daily routine and lifestyle, developing cues and rewards, and contingency contracting. Cues, or prompts, are often one of the most effective and efficient behavioral strategies to enhance medication adherence. Specialized pill containers in which the day of the week appears on each cell can be conveniently near one's toothbrush to prompt daily, habitual behaviors. Toothbrushing becomes the behavioral cue and reinforces medication-taking behaviors.

A final intervention found to be quite successful in improving and maintaining high levels of adherence to medical recommendations is that of social support, either from a health care professional or within one's personal environment. Factors that increase adherence include perceived support from the provider, patient satisfaction with the medical visit, and the support of family members in the home environment.

Adherence to medical recommendations continues to be a major concern for patients with long-term medical conditions. In order to maximize the benefit of the medical treatment, both physician and patient need to work together to achieve the common goal. The health care professional can enhance adherence by clarifying and tailoring the regimen, identifying behavioral cues, and enlisting and encouraging family members to be supportive.

Donald E. Morisky

(see also: Behavior, Health-Related; Enabling Factors; Health Belief Model; Health Promotion and Education; Patient Educational Media; PRECEDE-PROCEED Model; Predisposing Factors; Primary Care )


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DiMatteo, M. R., and DiNicola, D. D. (1982). Achieving Patient Compliance: The Psychology of the Medical Practitioner's Role. New York: Pergamon.

Friedland, G. H., and Williams, A. (1999). "Attaining Higher Goals in HIV Treatment: The Central Importance of Adherence." AIDS 13:S61S72.

Haynes, R.; Taylor, D.; and Sackett, D., eds. (1979). Compliance in Health Care. Baltimore, MD: Johns Hopkins University Press.

Morisky, D. E.; Green, L. W.; and Levine, D. M. (1986). "Concurrent and Predictive Validity of a Self-Reported Measure of Medication Adherence." Medical Care 24:6774.

Smith, S. K. (1996). "Patient Noncompliance with Wearing and Replacement Schedules of Disposable Contact Lenses." Journal of American Optometric Association 67:160164.

Straka, R. J.; Fish, J. T.; Benson, S. R.; and Suh, J. T. (1996). "Magnitude and Nature of Noncompliance with Treatment Using Isosorbide Dinitrate in Patients with Ischemic Heart Disease." Journal of Clinical Pharmacology 36:587594.