The ability of patients to follow treatments in an optimal manner is frequently compromised by more than one barrier. Interventions to promote adherence require several components to target these barriers, and health professionals must follow a systematic process to assess all the potential barriers.
Given that interventions are available, why has the adherence problem persisted? One answer concerns their implementation. There has been a tendency to focus on unidimensional factors (primarily patientrelated factors). All five dimensions (social and economic factors, health care team and systems-related factors, therapy-related factors, condition-related factors and patient-related factors), should be considered in a systematic exploration of the factors affecting adherence and the interventions aimed at improving it.
While many interventions (e.g. education in self-management (25-34); pharmacy management programmes (35,36); nurse, pharmacist and other non-medical health professional intervention protocols (37-43); counselling (44,45); behavioural interventions (46,47); follow-up (48,49) and reminders, among others), have been shown to be effective in significantly improving adherence rates (50-54), they have tended to be used alone. A single-factor approach might be expected to have limited effectiveness, if the factors determining adherence interact and potentiate each other's influence as they are likely to do.
The most effective approaches have been shown to be multi-level - targeting more than one factor with more than one intervention. Several programmes have demonstrated good results using multilevel team approaches (55-57). Examples include the Multiple Risk Factor Intervention Trial Research Group, 1982 (58) and the Hypertension Detection and Follow-up Program Cooperative Group, 1979 (59). In fact, adequate evidence exists to support the use of innovative, modified health care system teams rather than traditional, independent physician practice and minimally structured systems (60,61).
Various interventions are already being implemented by many different health care actors. Although not all of these actors are directly responsible for providing health care, they nevertheless have an important role in improving adherence because they can influence one or more of the factors that determine adherence.
The work that is being done to improve adherence and the persons performing the work are described below.
A. Social and economic interventions
Policy-makers who have the major responsibility for designing and managing the health care environment need to understand the ways in which social and economic factors influence adherence.
The main economic and social concerns that should be addressed in relation to adherence are poverty (62), access to health care and medicines, illiteracy (62), provision of effective social support networks and mechanisms for the delivery of health services that are sensitive to cultural beliefs about illness and treatment. (For more information see Annex 4.)
The high cost of medicines and care is consistently reported as an important cause of nonadherence in developing countries. Universal and sustainable financing, affordable prices and reliable supply systems are required if good rates of adherence to therapies are to be achieved. Considerable efforts are being made by WHO's partners to improve access to medicines and care worldwide.
Community-based organizations, education of illiterate patients, assessment of social needs (63) and family preparedness have been reported to be effective social interventions for improving adherence (64).
Social support (i.e. informal or formal support received by patients from other members of their community), has been consistently reported as an important factor affecting health outcomes and behaviours (65,66). It has also been reported to improve adherence to prescribed recommendations for treating chronic conditions (67), such as diabetes (68-78), hypertension (79,80), epilepsy (81-86), asthma (87) and HIV/AIDS (88-92), and to some preventive interventions such as breast cancer screening guidelines (93) and follow-up for abnormal Pap smears (94,95). So far, social support has not been shown to affect adherence to smoking cessation therapies (96-98).
Good examples of successfully implemented community-based programmes are the medication groups (99) and the peer/community support groups. The objectives of these programmes are:
- to promote the exchange of experiences of dealing with a disease and its treatment;
- to provide comprehensive medical information; and
- to promote patients' responsibility for their own care.
There is substantial evidence that peer support among patients can improve adherence to therapy (88,100-107) while reducing the amount of time devoted by health professionals to the care of patients with chronic conditions (107-109).Many other community interventions have also been shown to result in economic and health benefits by improving patients' self-management capacities (110-117) and/or by the integration of the provision of care (57,118-121).
The participation of patients' organizations, with the support of community health professionals (122), has been shown to be effective in promoting the maintenance and motivation required for the self-management of chronic diseases, as well as keeping the patient active in the knowledge of his or her disease and in the acquisition of new habits (110,111,113-115,123,124).
There are three different types of patients' organization (PO):
- Patient's organizations directly owned and managed by the health care provider (e.g. health maintenance organizations (HMOs) in the United States);
- Patient's organizations directly owned by patients, but promoted, organized and supported by public health care providers (as in Mexico); and
- independent Patient's organizations with no ties with health care providers.
Unfortunately, the Patient's organizations that have no ties with health care providers usually lack the health care programmes required for supporting patients' self-management. Their effectiveness has not been evaluated and such organizations usually focus mainly on patient advocacy.
Although well-established group interventions do exist, few patients are informed by health professionals of the benefits of joining support groups for improving self-management of chronic conditions. Further evaluation is needed to assess the effectiveness and cost-effectiveness of these organizations in enhancing adherence.
WHO, ministries of health and development agencies have a major role in promoting and coordinating community-based efforts to tackle social and economic factors affecting adherence to therapies.
B. Health care team and health system interventions
The issue of nonadherence has caught the attention of front-line health service providers and health researchers for a long time. However, opinion leaders among policy-makers have yet to adopt the issue as a policy target. This report can be used to focus attention on the consequences of poor adherence not only for population health, but for the efficiency of the health care system and to demonstrate the key role that policy-makers have to play.
Adherence is a multidimensional issue where different health care actors' efforts meet.
Health leaders at many different levels contribute to shaping a health system to meet the needs of its constituents. The way that health systems operate, the types of services and resources that are available and accessible to the population, and the ways in which health providers deliver treatments are of primary concern here.
This review found five major barriers inextricably linked to health system and team factors:
- lack of awareness and knowledge about adherence;
- lack of clinical tools to assist health professionals in evaluating and intervening in adherence problems;
- lack of behavioural tools to help patients develop adaptive health behaviours or to change maladaptive ones;
- gaps in the provision of care for chronic conditions; and
- suboptimal communication between patients and health professionals.
No single intervention or package of interventions has been shown to be effective across all patients, conditions and settings. Consequently, interventions that target adherence must be tailored to the particular illness-related demands experienced by the patient. To accomplish this, health systems and providers need to develop means of accurately assessing not only adherence, but also those factors that contribute to it.
Because health care providers could be expected to play a significant role in promoting adherence, designing and implementing interventions to influence what they do would seem a reasonable strategy. Although there have been efforts in this area, it is possible that they have had less-than-optimal power because they have not conveyed a sufficiently powerful skill set and/or the skills have not been widely adopted in practice.
To make this way of practice a reality, practitioners must have access to specific training in adherence management, and the systems in which they work must design and support delivery systems that respect this objective. For empowering health professionals an "adherence counselling toolkit" adaptable to different socioeconomic settings is urgently needed that will systematically assess, suggest interventions and follow up patients' adherence.
Such training needs to address three main topics simultaneously.
The information on adherence. A summary of the factors that have been reported to affect adherence, the effective interventions available, the epidemiology and economics of adherence and behavioural mechanisms driving patient-related adherence.
A clinically useful way of using this information and thinking about adherence. This should encompass assessment tools and strategies to promote change. Any educational intervention should provide answers to the following questions: How should patients be interviewed to assess adherence? How can one learn from local factors and interventions? How should priorities be ranked and the best available interventions chosen? How should the patients' progress be followed up and assessed?
Behavioural tools for creating or maintaining habits. This component should be taught using "role-play" and other educational strategies to ensure that health professionals incorporate behavioural tools for enhancing adherence into their daily practice.
Some information is available on training health professionals to perform patient-tailored interventions effectively. Ockene et al. (125) reported the effectiveness of short patient-centred interventions in three different randomized clinical trials: the WATCH study (diet) (126,127), the Project Health (alcohol) (128), the Nurse-Delivery Diabetic Smoking Intervention Project (129) and the Physician-Delivered Smoking Intervention Project (smoking cessation) (130). The latter found a statistically significant improvement in smoking quitting rates associated with 5-9 minutes of intervention.
It is clear from these studies that good adherence requires a continuous and dynamic process. Practitioners (and other health enablers) often assume that the patient is, or should be, motivated to follow a best-practice protocol. However, recent research in the behavioural sciences reveals this to be an erroneous assumption. The patient population can be segmented according to level-of-readiness to follow health recommendations (131-133). The lack of a match between the patient's readiness and the practitioner's attempts at intervention means that treatments are frequently prescribed to patients who are not ready to follow them.
Although adherence interventions directed towards patients have typically focused on providing education to increase knowledge, the available evidence shows that knowledge alone is not enough. Roter et al. published a meta-analysis of adherence-enhancing interventions which concluded that "no single strategy or programmatic focus showed any clear advantage compared with another and that comprehensive interventions combining cognitive, behavioural, and affective [motivational] components were more effective than single-focus interventions" (134). Information alone is not enough for creating or maintaining good adherence habits. First-line interventions to optimize adherence must go beyond the provision of advice and prescriptions. If either the perceived value of adhering, or confidence, is low, the likelihood of adherence will also be low.
Health care providers can learn to assess the potential for nonadherence, and to detect nonadherence itself. They can then use this information to implement brief interventions to encourage and support progress towards adherence. A conceptual framework that explains how patients progress to adherence will help practitioners to tailor their interventions to the needs of the patient.
More research is required in this area. New, sustainable initiatives targeting providers could aim to impart knowledge about the broad determinants of the problem and of specific strategies for addressing them, in ways that can be systematically implemented in practice.
The evidence reviewed for this report suggests that it would be helpful to create a shift in provider perspective that supports tailoring of interventions to the needs of individual patients, and to teach specific strategies to address those needs. One of the problems in this area has been the relatively low levels of knowledge transfer. The results of effective studies have not been widely implemented in practice. This highlights the need for educational programmes that go beyond describing the problem, and that convey solutions to everyday problems in practice.
WHO and many ministries of health are working to improve the provision of health care, but a lot of work still needs to be done on the development of appropriate care for chronic conditions.
C. Therapy-related interventions
In studies of therapy-related interventions, the main barriers to adherence were found to be the dose frequency and the incidence of side-effects. Pharmaceutical companies in partnership with health professionals and researchers are addressing these problems. The health system has an important role in minimizing the impact of side-effects on patients.
D. Condition-related interventions
Disease-specific demands, symptoms and impairments are the targets of health professionals. These actors could provide optimal care by identifying and treating these problems, as well as identifying and treating co-morbidities that affect adherence. For example, because of the high prevalence of depression and its considerable effect on adherence, adherence counselling interventions should include systematic screening for depression.
E. Patient-related interventions
The major barriers to adherence described in the literature reviewed for this report were lack of information and skills as they pertain to self-management, difficulty with motivation and self-efficacy, and lack of support for behavioural changes.
These barriers were especially significant for those interventions intended to change habits and/or lifestyles, but also affected medication use. WHO acknowledges the necessity of supporting patients' efforts at self-management. Many researchers are working to develop or improve and disseminate self-management guidelines.
Global changes in the delivery of health services and shrinking health care budgets have also contributed to a need for patients to become more able to manage their own treatments. The development of self-management interventions aimed at improving motivation and adherence, based on the best available evidence, will help to fill this need. This work can support efforts by patients' organizations to engage and support their members.
Increasing the impact of interventions aimed at patient-related factors is essential. There is a wealth of data from the behavioural sciences demonstrating the efficacy of specific strategies. Although it is well known that education alone is a weak intervention, many interventions continue to rely on patient education to encourage patients to adhere to their treatment. Patients need to be informed, motivated and skilled in the use of cognitive and behavioural self-regulation strategies if they are to cope effectively with the treatment-related demands imposed by their illness. For the effective provision of care for chronic conditions it is necessary to activate the patient and the community who support him or her (135).
A continuous effort is being made to improve the provision of information to patients, but motivation, which drives sustainable good adherence, is one of the most difficult elements for the health care system to provide in the long term. Although health professionals have an important role in promoting optimism, providing enthusiasm, and encouraging maintenance of health behaviours among their patients (136), the health systems and health care teams experience difficulties in constantly motivating patients with chronic conditions. These difficulties have led to an increased interest during the past decade, in the role of community-based educational and/or self-management programmes aimed at the creation and maintenance of healthy habits, including adherence to health recommendations.