There are 5 major groups of factors that influence adherence: 1) socioeconomic factors; 2) factors related to the healthcare system and treatment teams; 3) factors related to the attributes of treatment; 4) factors related to health conditions; and 5) patient factors. Factors related to the healthcare system and treatment teams in connection to the primary prevention of cardiovascular diseases include poor insurance systems, poor quality of education for healthcare personal, overworked medical practitioners, short consultation time, absence of evaluation or reward systems for medical practice, lack of cooperation from the community, absence of self-management programs, and poor management for adherence. Factors related to the attributes of treatment include the complexity of prescriptions, long durations of treatment, experiences of treatment failure, frequent changes in prescriptions, long periods before the manifestation of therapeutic effects, and side effects. Factors related to health conditions include mild or no symptoms, absence of physical, psychological, or social disabilities, and the slow progression of diseases. These characteristics have grave effects on a patients’ awareness of risks and the priority of treatments in the primary prevention of cardiovascular diseases.2) A stronger rapport between a patient and healthcare professional has been found to improve adherence.15)

Patient factors include knowledge, attitudes, beliefs, awareness, and expectations. There is a complex interplay among motivations for treatment, self-efficacy to continue therapy, and expectations for the outcomes of therapy or non-adherence. Other patient factors include forgetfulness, stress, anxiety about side effects, low levels of motivation, lack of knowledge or ability for symptoms or treatments, low self-awareness for the need of treatment, ignorance about therapeutic effects, negative beliefs about therapeutic effects, misunderstanding or disregard of the disease, doubts about the diagnosis, neglect of risk, misunderstanding of treatment protocols, rejection of consistent visits, low expectations for therapeutic benefits, failure to frequently visit, frequently being absent from educational programs, despair or negative emotions, disappointment with medical professionals, fear of dependence, anxiety over complex prescriptions, and labeling effects.2)

Awareness of the need for drug treatment is affected by the symptoms themselves as well as awareness of risk.16) Diseases related to the primary prevention of cardiovascular diseases have few symptoms and take a long time before the manifestation of complications or therapeutic benefits. This creates major disadvantages in awareness of the need for drug treatment. There can also be a strong abstract concern about the side effects of medication, such as misconceptions of side effects, burden of having to take medication every day, and/or drug dependency during long-term treatment.17) These views can foster negative attitudes about all types of drugs and may be associated with broader caution or doubts about chemicals detected in food or the environment resulting in further generalized suspicion of science, medicine, or technology itself.18)19)20)

According to the WHO, healthcare systems have an influence on adherence. The control of consultation time, distribution of resources, medical reimbursement systems, communication, and information systems can have impacts on accessibility to medical services. A desirable system has the following attributes: healthcare providers are given enough time to support behavior related to adherence; threats to patient interviews or education due to the lack of reimbursement are improved; resource distribution that can lower adherence by too many requirements and stress from healthcare providers is improved; continuous treatment from the same provider is received; data on prescriptions between doctors’ offices and pharmacies is shared; and ongoing counseling, including contact by phone call, is encouraged. Unless these systematic requirements are met, it will be limited for healthcare providers and patients to achieve adherence due to suppression from external factors.

The WHO report recommends that policy authorities set a policy goal of improving adherence and play a central role in adherence issues as they are related to the efficiency of the healthcare system as well as the health of the population. There are 5 issues concerned with adherence with respect to policy making: 1) lack of awareness and ignorance with regard to adherence; 2) lack of clinical tools to assist medical personnel to evaluate and intervene adherence issues; 3) shortage of behavioral tools needed to change negative behavior as well as promote positive ones; 4) a gap in rewards for the treatment of chronic diseases; and 5) lack of communication between patients and medical personnel. These issues can be solved by developing accurate evaluation tools for adherence and identifying factors influencing it. Healthcare providers play important roles in the improvement of adherence and in reasonable interventions at the healthcare system level which can, in turn, have impacts on their behaviors.

Even with the best coping measures at the healthcare system level, it is not sufficiently effective at the social level. The social ecological model raises the need for systematic changes that are broader and more diverse than just families and schools in order to maintain healthy behavior for a long period of time. Factors influencing patients’ behavior in the ecological aspect include personal, interpersonal, organizational, community, and public policy factors. There should be measures across all these areas. A recent emphasis on social context proposes an approach of intervening behavioral changes through the organized fusion of community situations, the government, and policies in addition to the healthcare system.

It is critical to take a systematic approach to assessing potential barriers to interventions for improved adherence while identifying factors causing inconvenience. In general, it is because of dependence on fragmentary approaches that adherence issues are not resolved. In many cases, only single dimension approaches limited to patient factors have been taken. It is common to use self-management programs that are known to be effective,21)22)23) intervention programs by nurses, pharmacists, and experts of other medical backgrounds,24)25)26) counseling,27)28) or behavioral interventions, follow-up, and reminders29) separately. However, considering the interactions among these factors, the effect is very likely to be limited if only used separately.

A multidimensional team intervention seems to be the most effective. This team approach, for instance, has been reported in Multiple Risk Factor Intervention Trial and The Hypertension Detection and Follow-up Program research. An innovative and advanced medical service team has been found to be more effective than conventional therapy by doctors alone and minimally structured methods.30)31)

Since the 1990s, the transtheoretical stage of change models has been applied in research and therapy with a focus on behavioral changes at the individual level. This approach can be applied to many different theoretical models simultaneously. A synthetic application to PCCC is helpful for the improvement of adherence. Here, application means “to have patients get involved and help them make a therapeutic plan and stick to it.”56)57)58) In PCCC, the following types of questions are asked: 1) open-ended questions to induce patients in a decision-making process; 2) questions about the patients’ thoughts about risks; and 3) questions that enable a comparison between the costs and benefits in behavioral changes and adherence. These questions cover the 5 areas for a time efficient application of PCCC: 1) whether patients have the desire or motivation to change their behavior; 2) whether they have had experiences of attempting behavioral changes in the past and what their experiences were; 3) what hindered their behavioral changes; 4) what they think about their surrounding conditions and abilities for behavioral change; and 5) plans for behavioral change and times of revisits. It has been emphasized that past experiences should be utilized to facilitate the motivation and efficacy patients. In PCCC based on the health belief model, records are made of 1) the patients’ cognitive states to the risk of their behavior and deteriorating diseases; and 2) the patients’ beliefs about their behavioral changes to lower the risk. In the relapse prevention model, education and tools to determine the characteristics and clues of high-risk situations should be provided. Patients should be equipped with coping methods for each situation in detail including communication, initiation of support, and stress management methods. Well organized PCCC should be sequentially progressed in the following steps.

Empowerment is allowing patients to control their own situations and exercise their rights in order to take care of themselves and maximize their individual quality of life. The WHO defines empowerment as “a process through which people gain greater control over decisions and actions affecting their health” and it should be seen as both an individual and a community process (page 16).60) In terms of the primary prevention setting, it means that patients should gain more control over the shared decision-making process as well as actions related to lifestyle changes. There are 5 dimensions of adherence factors, and the other factors of adherence are neglected in the actual field of treatment with the tendency to continue labeling patient factors as causes of non-adherence. According to research findings, however, patients get frustrated when they are not encouraged to voice their opinions and have them reflected in the decision-making process about their treatments. The more they feel they are not given any decisions of authority, the more negative their attitude will become towards therapy and their adherence is likely to be lower.61) Adherence has something to do with an individual patient’s way of judging the potential side effects and need for therapy.19)62) It is helpful to explore the patients’ major beliefs regarding their concerns and need for therapy, listen to their concerns, and help them become clear in understanding their ideas about decision-making and adherence. Empowerment helps to improve adherence in drug therapy to regulate the risk factors of cardiovascular diseases.4)

Clinical question 5: Does patient empowerment improve adherence?

Consensus: Patient empowerment improves adherence in the primary prevention of cardiovascular diseases.

The patients’ motivation for adherence is influenced by the unique values they give adherence and their views on its efficacy.63) Motivational interviews are effective in facilitating lifestyle changes to manage risk factors.64) The clear goal of behavioral therapy to improve overall adherence is to establish an internal motivational state by reinforcing the patients’ awareness of the importance of adherence and their efficacy about their self-management abilities.59) In motivational interviews, motivational strategies can help patients move to therapeutic behavior by examining their motivational state and giving them feedback based on PCCC. Motivational strategies are also valid in changes to the patients’ habits, lifestyles, or attitude towards medication.4) Structured training for motivational strategies has not been well implemented but seems to be important to assure the quality of PCCC.65)

Clinical question 6: Do motivational strategies improve adherence?

Consensus: Motivational interviews are effective in facilitating lifestyle changes to manage risk factors.

There is no doubt that the improvement of adherence is a continuous and dynamic process. There is a misconception that patients are naturally motivated and follow the best therapy. In real treatments, it is common for clinical specialists to prescribe one-sided intervention attempts or treatments off the target to patients who are not yet ready.2) There is the usual focus on education to increase knowledge to improve adherence, but knowledge alone is not enough to create and maintain good adherence. Thus, it is necessary to make a shift from the provider’s perspective that is oriented toward complex and detailed therapies to the patient’s own perspective, for instance, educating patients in how they should respond for their specific needs.

The transtheoretical model in stages of changes reflects the need for a specific intervention according to the stages of a certain behavior. The stages are as follows: 1) Pre-contemplation stage: patients have no intention to change a certain behavior; 2) Contemplation stage: they are considering behavioral change but are not prepared to start it; 3) Preparation stage: they are willing to start a behavioral change within a couple of months; 4) Action stage: they have actually started to change their behavior; and 5) Maintenance stage: they have implemented a change and strategy to prevent a relapse. These stages can be applied to various behavioral models. Clinical specialists should implement the proper method to establish the patients’ current stage of change and help them make sequential changes. Forced encouragement or advice can be effective for patients at the action stage, but it may cause resistance in patients at the pre-contemplation stage, in which an interview with a focus on the provision of information and a focus on motivation will be helpful in a PCCC environment.66)67) Transtheoretical model was effective for smoking cessation and its efficacy for weight reduction was proved by randomized trial.66)68)

Clinical question 7: Does an approaching strategy according to stages of change improve adherence?

Consensus: Interview strategies according to stages of change improve adherence.

It is known that the complexity of prescriptions involving the total number of drugs and frequency of medication usually lowers medication adherence in drug therapy for cardiovascular diseases.69)70) It has been reported that taking medication once a day increased adherence with regards to the frequency of the medicine.71)72) In hypertension therapy, single pill combinations increased medication adherence and decreased the risk of lower adherence more than the conventional combination therapy.73)74)75) Single pill combinations increased medication adherence partly because they were cheaper than combination therapy.76) It is expected that an increased number of drugs will drop adherence, but research has reported that patients who felt that their illness was serious tended to take their medication better to a certain extent even with increased drugs. A study reported that adherence was the highest when patients took 4 to 5 drugs.77)

Polypill refers to a single pill of heterogeneous medicine for 2 different diseases or more such as hypertension and dyslipidemia. It has been reported that polypills improve medication adherence and are effective for the primary and secondary prevention of cardiovascular diseases.78) Meta-analysis results show that polypill prescriptions improved medication adherence for blood pressure, cholesterol, and antiplatelet drugs.79) They have especially improved cholesterol treatment in low-income countries and socioeconomically alienated classes.80) Polypills have advantages of improving adherence, being advantageous for the management of risk factors, and increasing the quality of life. They also have a couple of disadvantages, including difficulties with the regulation of dosage and possibilities of increased dosage. However, the efficacy for long-term prognosis needs to be proved.81)

Clinical question 8-1: Does a reduced number of drugs based on single pill combinations improve medication adherence?

Consensus: A reduced number of drugs based on single pill combinations improves medication adherence.

Clinical question 8-2: Do polypills increase medication adherence?

Consensus: Polypills improve medication adherence.

In its preventive cardiology report in 2002, the American Heart Association put a major emphasis on the active role of patients as well as the practice of the healthcare system for improved adherence (Table 1). Doctors, nurses, pharmacists, and physician assistants should all practice the key concepts of 1) PCCC, 2) interview or counseling, and 3) behavioral science so that patients can perform their roles. As health education nurses, nutritionists, and psychology counselors are added to the group of healthcare providers, adherence can be promoted through education, motivation, monitoring, and feedback.82) In metabolic syndrome patients, collaboration between nutritionists and physical therapists improves adherence in lifestyle changes.83) Collaboration between nutritionists or pharmacists and nurses improves the adherence of cardiovascular and hypertension therapy.84)85)86)87) A total approach through diverse collaborations in the clinic improves the adherence of a program for lifestyle changes.88)

Under specific strategies to develop systematic team approaches to provide therapy to improve adherence, clinical specialists should receive specific education on adherence intervention. The healthcare system should also plan and deliver a corresponding medical service. If there are no established training sets of clinical skills applied broadly in actual therapy, a team approach will not be effective, even with a well-established program as long as it is not dedicated to adherence intervention. That is, one of the major issues in current education is that the efficacy of treatment proven in clinical research is not implemented in real world practice due to the lack of an educational strategy for healthcare personnel to contribute team approaches to improve adherence.

It is therefore urgent to develop a “PCCC training tools set for adherence improvement” that will assess adherence systematically, propose an intervention plan, and promote effective follow-up through the well-developed capabilities of healthcare staff. Such education for healthcare personnel should include 3 topics. The first topic is information about adherence: 1) factors and intervention methods affecting adherence; 2) dynamics and economics related to adherence; and 3) behavioral mechanisms to determine patient factors related to adherence. The second topic describes how to effectively make use of clinical information regarding adherence improvement and how to think about strategies for evaluating and facilitating changes. With such education, healthcare providers should be able to explain 1) interview methods to assess adherence, 2) learn from local factors and interventions, 3) choose the best intervention, and 4) assess the progress and follow-up. The third topic should cover behavioral tools that develop and maintain lifestyle changes. Medical experts should be trained for each element of these tools with role play and pedagogical strategies; consequently, they should be able to confidently apply behavioral tools to improve adherence to daily practice.

Clinical question 9: Does collaboration among nurses, pharmacists, and nutritionists improve adherence?

Consensus: A multi-disciplinary team unit approach involving nurses, pharmacists, nutritionists, physical therapists, and behavior therapists improves the adherence needed in the primary prevention of cardiovascular diseases.

Various behavioral lifestyle changes improve adherence for the primary prevention of cardiovascular diseases.3) Psychological/behavioral theoretical grounds related to adherence have been established. The basic foundations for approaches related to adherence include theoretical concepts and behavioral change models such as 1) transtheoretical theory and the stages of change model; 2) health belief model; 3) social cognitive theory; 4) relapse prevention model; and 5) social ecological model.89)90)91) The 5 stages of change are the 1) pre-contemplation stage, in which patients do not take changes into consideration; 2) the contemplation stage, in which they are considering changes but are not prepared to act; 3) the preparation stage, in which they are ready to act within a couple of months; 4) the action stage, in which they are showing behavioral changes; and 5) the maintenance stage, in which they implement measures and strategies to prevent a relapse. This model can be applied in combination with other models. Clinical specialists’ encouragement policies may be effective for patients at the action stage, but patients at the pre-contemplation stage may reject them. Clinical specialists need to encourage their patients’ step by step development by taking an approach that fits each of their stages of change. Neither clinical specialists nor patients should be discouraged or alienated at any of these stages.82)

The health belief model is useful for exploring the beliefs of individual patients regarding factors influencing the possibility of behavioral change. Within the larger framework where the possibility of behavioral change is determined by an individual patient’s perceptions of 1) their health conditions; and 2) gain and loss according to behavioral change, such sociodemographic features as race, personality, socioeconomic background, and health knowledge have impacts on their perceptions. Patient perceptions of severity and risk affect their perceptions of their health conditions. In chronic diseases, cues from symptoms play weak roles, whereas cues from education and media information play more important roles.

Social cognitive theory emphasizes interpersonal, cognitive, and environmental impacts on patient behavior and the ways they are applied to behavioral change. The basic elements of a self-management program applicable to cardiovascular diseases include self-observation and analysis of behavior, self-management including external stimuli, training for behavioral know-how, behavior substitution, and behavior reinforcement. In social cognitive theory, self-efficacy is related to motivation, which is the patients’ willingness to participate in their behavioral change. A wide variety of specific methods related to behavioral change are applied in practice. Examples of external cognitive assistive tools include written contracts, training for behavioral know-how, self-supervision, reinforcement of self-efficacy, spouse and social support, contact by phone call/mail, and notifications or messages.

In the relapse prevention model, a relapse is considered a stage of behavioral change. An early relapse state is a turning point between regression to old behavior and positive changes. A relapse goes through an emotional, conscious, and physical relapse stage and is influenced by various factors, including self-efficacy, predictions for outcomes, desire, motivation, coping abilities, emotional states, and interpersonal relationships. Therefore, patients need to master know-how to recognize the cues and characteristics of high-risk situations. It is critical to make a detailed plan to cope with a situation including communication, mobilization of support, and stress management.

In the social ecological model, the emphasis is on changes across the social system encompassing the individual, interpersonal, collective (school and workplace), community, and public policy levels since interventions at the healthcare system level will not guarantee consistent effects long-term. For the promotion of physical activities, for instance, several components of an urban environment should be taken into consideration, including safe pedestrian pavements, parks, spaces for leisure, and nighttime lighting.

The information–motivation–behavioral skills model shown in Figure 1 is a useful conceptual framework to guide thinking about complex health behaviors. In both prospective and correlational studies, the construct of information, motivation, and behavioral skills can explain 33% of the variance in behavioral change.92)93)

Clinical question 10: Do behavioral lifestyle changes improve adherence?

Consensus: Various behavioral lifestyle changes improve adherence for the primary prevention of cardiovascular diseases.

Various behavioral therapy strategies including skill training for cognitive behavioral therapy to improve adherence in the management of cardiovascular risk factors have been found to be effective.52) Cognitive behavioral therapy via telephone counseling improves the patients’ lifestyle changes and lowers their risk of cardiovascular disease.94) Cognitive behavioral therapy via telephone counseling, smartphone, internet, and education improves the adherence of medication and adherence of lifestyle changes in hypertension patients and increases their blood pressure control rates.95)96)97)98)99) A doctor’s strong and clear advice for smoking cessation increases the patients’ success rate to quit smoking more than his or her suggestions.100)

Clinical question 11: Does cognitive behavioral therapy improve adherence?

Consensus: Cognitive behavioral therapy improves adherence for the regulation of cardiovascular risk factors.

When hypertension patients are not correctly aware of the risks of cardiovascular events, their adherence drops.46) Education on the disease enhances medication adherence and leads to better blood pressure management.11)24)101) Home visit education for the elderly with diabetes can improve medication adherence.24)102) When patients believe that blood pressure drugs are not effective for lowering their blood pressure or have prior knowledge of their side effects, it can reduce their medication adherence.64) Education that emphasizes only the risk of the disease generates small effects on the improvement of adherence, even when the effects of education are recognized. Education on the awareness of risk alone is not sufficient to increase adherence. Therefore, multi-disciplinary and multidimensional approaches should be combined to improve adherence.46)103) It is more important to educate patients according to their immediate interests using acceptable approaches than to emphasize potential cardiovascular events in 5 or ten years to improve adherence.46)

Clinical question 12: Does education on the risk of complication improve adherence?

Consensus: Education on the risk of complications improves adherence.

As part of a national health program to prevent non-contagious diseases, leaflets containing behavioral information for health promotion were distributed and examined for their effects. The results show that such leaflets generated no significant effects. People had no interest in such leaflets, and although such leaflets could help with their decisions, they did not change their actual behavior.104)

Clinical question 13: Does the distribution of printed materials emphasizing adherence improve it?

Consensus: Printed materials about behavioral reinforcement for health promotion have limited effects on adherence.

In education on the reduction of cardiovascular risks for African Americans with a cardiovascular disease or risk, additional participation in a church music program (for example, gospel hymns) helped them to participate in health education longer and improved their health.105)

Clinical question 14: Does a workplace/community health management program improve adherence?

Consensus: A workplace/community health management program improves adherence.

A 1-hour session of telephone counseling once a week over 6 weeks can improve patient lifestyle changes and lower their cardiovascular risk.94) When nurses used phone calls for diabetes patient education, lifestyle changes, and drug regulation, patients improved in the adherence of dietary habits and self-measurement of blood glucose, and regulated their blood sugar level better.106)107) Regular phone calls to hypertension patients can improve their adherence to medication and lifestyle changes and lower their blood pressure95)108)109)110) and further save hospital and medical expenditures.110) When such phone calls stop, however, the effects dwindle or disappear.108)109) A home visit program at an interval of 2–4 months for elderly patients with hypertension improved their knowledge of hypertension, blood pressure monitoring, and adherence in meal regulation and medication.111) In elderly patients with diabetes, education via home visits and activities to increase their awareness of diabetes improved their adherence of taking drugs for diabetes.24)102)

Clinical question 15: Does counseling by telephone or home visits improve adherence?

Consensus: Counseling or monitoring by telephone or home visits improves adherence.

Incentives did not lead to a huge improvement of health outcomes in relation to chronic diseases or an increase in health-oriented behavior.112)113) There was no improvement in adherence in studies for prevention programs, medication adherence, or treatment for diabetes.113)114)115) However, a study reported significant efficacy of lottery-style incentives on weight reduction in a short-term period.116) Positive incentives did not show statistically significant differences in medication adherence. Further studies on more diverse groups and drugs are needed.117) Incentives offered both to doctors and their patients were more effective for reducing lipid level.118) Monetary incentive rewards could be effective for weight regulation and physical activities. Negative incentives were more effective than positive incentives, and group-based incentives were more effective than individual incentives.119)120)

Clinical question 16-1: Do positive incentives improve adherence?

Consensus: Incentives offered to patients did not improve adherence in the primary prevention of cardiovascular diseases.

Clinical question 16-2: Do negative incentives improve adherence?

Consensus: Negative incentives were effective for weight regulation and improved adherence in physical activities.

Meta-analysis results show that the self-measurement group showed an increased amount of physical activity compared to the control group.121) Self-measurement was effective for diet control when it was combined with other measures. It was more effective when patients were young, with higher level of education, and were positive.122) Self-measurement activities were helpful for interventions based on lifestyle changes and showed greater benefits when accompanied by other interventions such as counseling.123) However, in diet therapy, self-measurement for the sodium/potassium ratio in urine did not show a benefit.124) In hypertension patients, self-measurement of blood pressure improved medication adherence without improved adherence in lifestyle changes.125)

Home blood pressure measurement improves medication adherence126) and increases blood pressure control rate.109)127) In a high-risk cardiovascular group, the self-titration of dosage of antihypertensive drug according to measured home blood pressure level improved medication adherence and hypertension control rates.128)

Clinical question 17-1: Do self-measurement activities improve the adherence of lifestyle changes?

Consensus: Various self-measurement activities improve the adherence of lifestyle changes.

Clinical question 17-2: Does home blood pressure measurement improve medication adherence?

Consensus: Home blood pressure measurement improves medication adherence.

There are many patients who have low health literacy in real world practice. Low health literacy is common among elderly patients.129)130) Low health literacy weakens health conditions131) and increases hospitalization rates and management costs.132) Patients with low health literacy have a weak awareness of their diseases, suffer difficulties in communicating with medical personnel, are not good at following the doctors’ instructions, and have decreased adherence for medication and lifestyle changes.131)133)134)135) Poor health literacy resulted in poor regulation of blood pressure136) and blood sugar137)138) and greater possibilities of failure in smoking cessation139) and weight control.140) When patients with low health literacy were served by patient-centered drug labeling using prioritizing information, larger font size, and increased white space with standard medication intervals, adherence of taking medications for hypertension and diabetes increased 4 to 5 times.140) When flashcards or smartphone videos were used for patients with low health literacy, medication adherences of hypertension, diabetes, and heart failure were improved.141) Multifaceted approaches encompassing communication, education, reinforced social activities, and economic support can improve adherence with greater effects on patients with lower health literacy.134)142)143) The utilization of health information technologies, such as mobile apps, can improve the patients’ health literacy and adherence.144) When treating patients with low health literacy, medical personnel should give explanations loudly, clearly, and slowly, in bigger fonts, and make active use of pictures or videos.134)135) Patients should be assessed for their health literacy every 4 to 6 years to maximize the preventive effects for cardiovascular diseases.134)

Clinical question 18: Do activities of promoting health literacy improve adherence?

Consensus: Activities of promoting health literacy improve adherence.

Depression is known to decrease adherence to lifestyle changes165)166)167) and medication adherence including antihypertensive drugs.168)169)170) Antidepressant treatments for patients with depression in addition to cardiovascular diseases improves adherence for the primary prevention of cardiovascular diseases.45)171)

Clinical question 22: Does depression diagnosis and treatment improve adherence?

Consensus: The diagnosis and treatment of depression improves adherence.

The prevalence rate of self-reported cost related non-adherence in medication was reported as 16% in US elderly patients.172) Medication adherence drops according to the growing burden of medication costs on patients themselves. Vulnerable patients, including the elderly, may take less medicine due to the burden of medication costs.173)174)175)176)177)178)179)180)181) In all studies, medication adherence improved when patients did not have the burden of medication costs.53) Medication adherence was higher in generic drugs than branded drugs.179)182)183) Therefore, there is a need for research on medication adherence based on price differences between branded and generic drugs in domestic conditions.

Clinical question 23: Do cheaper drugs improve medication adherence?

Consensus: Reduction of medication cost improves medication adherence.