Adherence is defined as the degree to which behavior corresponds to a recommended therapeutic regimen (Haynes, Taylor, & Sackett, 1979). Numerous terms have been used to describe this behavior, including compliance, therapeutic alliance, and patient cooperation. Although the literature is filled with discussion of the acceptability of these terms and the differences between them, most investigators view the terms assynonymous and independent of the decision to engage in a particular therapeutic regimen. The most complete literature can be obtained from structured databases with the term compliance.
Adherence to health care regimens has been discussed in the literature since the days of Plato. However, little systematic attention was given to this phenomenon until the 1970s, when there was a proliferation of research. One of the first reviews of the literature was published in Nursing Research (Marston, 1970). Since that time there has been a profusion of research from a variety of disciplines. The majority of the research has been focused on patient adherence, although there is a smaller body of literature on the adherence of research staff to clinical protocols and a growing body of literature on provider adherence to treatment guidelines.
One of the issues that continues to arise in discussions of patient adherence is patient autonomy. Is non adherence a patient right or is adherence a patient responsibility? This argument presumes that the patient is aware of his or her own behavior and has consciously decided not to follow a treatment regimen. The literature suggests that fewer than 20% of patients with medication regimens consciously decide not to engage in a treatment program. Those patients who have decided to follow the regimen but do not carry it out are unaware of episodic lapses in behavior or have difficulty in integration of the health care regimen into their lives. The most common reasons given by patients for lapses in adherence are forgetting and being too busy. This group comprises on average 40% to 50% or more of patients in a treatment regimen. The problem of nonadherence is costly in terms of dollars and lives. The national pharmacy council estimates that nonadherence to pharmacological therapies costs approximately $100 billion annually (Grahl, 1994).
Although the cost of nonadherence to non-pharmacological therapies has not been estimated, the contribution to morbidity and mortality is high. Failures to quit smoking, to lose and maintain weight, to exercise regularly, to engage in safe sex practices, to avoid excess alcohol, and to use seat belts contribute significantly to declines in functional ability as well as to early mortality. Further data suggest that nonadherence to pharmacological as well as non-pharmacological therapies contributes to excess hospitalization and complication rates (Dunbar-Jacob &Schlenk, 1996).
Poor adherence then is a significant problem of direct relevance to nursing. Nurse practitioners may prescribe or recommend therapies. Home health and community nurses provide education and assistance in carrying out health care advice.
Hospital, clinic, and office nurses provide education regarding treatment plans. There is a need for intervention studies that will guide practice as nurses prepare and support patients in the conduct of treatment regimens. Research on adherence has been focused heavily on the determination of the extent of the problem and on predictors or contributing factors. Recent reports by the Cochrane Collaboration suggested that just 36 randomized controlled studies have evaluated interventions to improve medication adherence and examine both adherence and clinical indicators as outcomes. Fewer still have examined adherence to lifestyle behaviors. Most of these used general educational or behavioral counseling interventions. Just 1/3 of the interventions were found to have an effect on both adherence and outcome. Strategies that showed effectiveness were those that included components of self-management and/or enhanced attention by health professionals.
One problem in evaluating interventions and identifying relevant predictors is that of measurement. Most clinical studies have relied on self-report of adherence. There is a growing body of evidence indicating that individuals do not report accurately and those reports are biased toward an overestimate of performance. Thus, alternative strategies are being used to obtain better information, such as electronic monitors, PDAs and other technologies. Future research on adherence should address strategies by which nurses can improve adherence to treatment regimens with attention directed toward various age groups, clinical populations, and regimen behaviors. The research would benefit from theoretical approaches to the problem of patient adherence and the design of intervention strategies. Effective strategies delivered by nurses have considerable promise of a favorable impact on health outcomes and costs (Dunbar-Jacob & Schlenk, 1996).