Introduction

Adherence can be defined as following medical recommendations. It is based on cooperation between the patient and the doctor and involves the patient’s active participation in following treatment plans and other recommended health behaviours [1]. Higher adherence is associated with better treatment outcomes, improved quality of life, and a reduction in complications associated with chronic diseases. It is estimated that lack of adherence in the healthcare system generates costs of approximately 6 billion PLN annually in Poland, and as much as 125 billion euros across Europe [2]. The data also indicate that as many as 50% of patients with chronic conditions do not fully comply with medical recommendations, and the health consequences of non-adherence result in approximately 200,000 deaths annually across Europe [3]. Many studies identify the doctor as the patient’s primary partner in the therapeutic process, and hold the doctor solely responsible for the treatment, not only for its success, but primarily for its failure. However, adherence is also an area of professional activity for other healthcare professionals involved in the therapeutic process, such as nurses, midwives, and physiotherapists. For example, in nursing practice, adherence refers to the extent to which a patient’s behaviour (including taking medications, following a diet, or making lifestyle changes) aligns with the treatment plan established in consultation with the medical staff [4].

In Poland, the legal framework for adherence is based on regulations that oblige all medical staff to provide patients with information and health education, which is the basis of their collaboration in the treatment process. Doctors, nurses, physiotherapists, midwives, paramedics, and pharmacists are required to promote adherence through patient education; however, the final decision rests with the patient (right to autonomy). The patient has the right to refuse to follow recommendations; however, medical staff should ensure that this decision is “informed”, which means that it was made after understanding the consequences of discontinuing therapy [5].

Doctors are obliged to promote adherence according to the Act on the Professions of Medical Doctor and Dentist (consolidated text: Journal of Laws 2024, item 1287 as amended): Information Obligation (Art. 31): A doctor has the duty to provide the patient with accessible information about their health condition, proposed and possible diagnostic and therapeutic methods and the foreseeable consequences of their application or abandonment [6]. The patient’s full understanding of these issues is a prerequisite for adherence. Informed consent means compliance with medical recommendations, but it is only possible if the patient consciously agrees to treatment after receiving comprehensive information. The doctor must include in the medical records the fact that such consent was given, as well as any refusal by the patient to follow the recommendations, which is crucial in the event of malpractice claims.

As far as nurses are concerned, their role in promoting adherence is strictly defined in the Act on the Professions of Nurse and Midwife (consolidated text: Journal of Laws 2024, item 814). The practice of nursing involves, among other things, teaching patients about health-promoting behaviours and preparing them for self-care during illness [7]. In this regard, emphasis is placed on educational competencies within the framework of, for example, coordinated care in primary health care. Nurses with appropriate qualifications may independently prescribe medications and issue prescriptions (continuation of therapy), which helps patients maintain continuity of treatment and improves adherence [8].

Adherence as a process

Contemporary healthcare standards emphasize patient empowerment, which makes adherence, that is the patient’s active participation in following agreed treatment recommendations, a key element of modern care. In contrast, the term compliance is associated with a more traditional, paternalistic model of healthcare, in which the patient’s role is viewed as passive acceptance of professional instructions. This latter type of relationship reflects the traditional role of the doctor/nurse in the therapeutic process. Another related concept is concordance, which describes a process of shared decision-making and agreement between the patient and healthcare professional regarding treatment choices. In this type of relationship, there is full agreement on the procedure, yet the patient is the key decision-maker in the therapeutic process. All in all, the key aspects of adherence relevant to members of the therapeutic team are partnership and shared responsibility. Adherence also involves building a relationship based on trust and shared decisions regarding the course of treatment. Practical aspects of adherence include, among others, attending follow-up appointments regularly, undergoing prescribed tests, and modifying habits (e.g., quitting smoking or increasing physical activity) [9]. Ensuring adherence requires identifying and addressing barriers that may prevent patients from adhering to recommendations or taking joint responsibility for their health. These are significant and critical limitations, such as lack of knowledge, fear of side effects of the treatment, or financial difficulties [10]. Table 1 summarizes the characteristics of compliance, adherence, and concordance with respect to their goals, the roles of participants, and the relationships within the healthcare decision-making team.

In order to improve treatment adherence, the entire healthcare team must work together, including pharmacists, whose role in the care of patients with chronic conditions has now been expanded to include medication reviews and patient education. The issue of improving adherence is particularly relevant in primary care, where a key role is attributed primarily to the activities of the general practitioner in the primary care setting [3, 11]. The level of patient education provided is also significant; in the primary care it is carried out not only by family physicians but also by community nurses. By regularly visiting patients in their homes, they can carry out the educational process, ranging from providing information to assessing acquired skills. The basis of this type of health education is a holistic approach, including peer education. Margaret Whitehead, a world-renowned authority in this field, identifies two key characteristics of the nurse’s role as a health educator. The first involves suggesting changes to the patient’s behaviours that negatively impact their health. The second involves ensuring patients’ access to and engagement in educational activities designed to lead to behavioural change. The effectiveness of education depends primarily on the patient’s awareness and willingness to take responsibility for their own health, rather than solely on the educator’s expectations [12].

Numerous studies have attempted to determine the causes of non-adherence. These have been identified as economic factors, such as high medication costs or difficulties accessing healthcare facilities, and psychological factors, such as denial of the illness, fear of side effects, or forgetting to take medication. A significant factor is the complexity of therapy, specifically its long duration, which necessitates giving up previous activities (often unhealthy ones) or involves complicated medication dosing, particularly in patients with multiple comorbidities and the elderly [13-16].

Difficulties in maintaining adherence fall into two main categories: unintentional and intentional barriers. The former include cognitive problems, for example missing doses of medication, which is often observed in older adults, or errors in understanding the dosing regimen, as well as mistakes resulting from low health literacy. This group also includes physical barriers (difficulty in swallowing medication, its unpleasant taste, problems with opening packaging, difficulty in operating equipment), and treatment complexity, such as complex dosing schedules, multiple daily administrations, and polypharmacy. On the other hand, intentional barriers include concerns about the side effects of the treatment (a conscious decision to skip a dose out of fear of the drug’s negative effects on the body), the absence of symptoms (e.g., patients with “silent” diseases, such as hypertension, often discontinue therapy when they do not experience immediate symptoms and conclude that the treatment is unnecessary). An important element related to intentional barriers is beliefs (lack of confidence in the effectiveness of treatment) or cultural worldviews that frequently clash with evidence-based medicine. A lack of trust in the doctor or a feeling of being judged causes patients to withhold facts related to their treatment [17-19].

Systemic and economic factors are major causes of non-compliance with treatment recommendations and a lack of cooperation within the therapeutic team. Notably, high treatment costs, particularly the prices of medications, are a frequent reason for discontinuing therapy. Despite reimbursement programmes, the cost of medication remains a significant barrier, especially for low-income patients. According to experts, communication gaps in the patient-doctor relationship are a key factor in ensuring adequate patient education in the primary care doctor’s office. Patients often leave the doctor’s office without knowing exactly how to take their medication or why it is necessary [20]. Moreover, lack of health literacy makes medical jargon a significant barrier for them. Staff shortages in healthcare facilities limit the time available for patient education during primary care visits, which results in poorer understanding of the treatment plan. The limited duration of primary care visits means that patients do not have the opportunity to ask questions about their concerns. If the treatment plan is imposed rather than negotiated (so-called shared decision-making), the patient feels less responsible for the therapy. Furthermore, information barriers between doctors of different specialties hinder the monitoring of the patient’s actual behaviour. These findings were published in a multicentre analysis, in which 1,499 patients who had experienced myocardial infarction and completed the 12-month coordinated specialized care programme (KOS-Zawał) were examined. Patients did not achieve the expected results in terms of lowering LDL cholesterol levels, reducing BMI, and quitting smoking [21].

Despite ongoing digitalisation (e-prescriptions, IKP – Internet Patient Account), data fragmentation persists. There is also a noticeable impact of medical misinformation on social media, which leads patients to replace medication with unconventional methods or adjust dosages based on unverified sources. The growing influence of social media means that patients are more likely to compare their primary care physician’s recommendations with unverified opinions found online, which makes them replace recommended medication with dietary supplements of unproven efficacy [20, 22].

Improving adherence in primary care may involve adopting strategies that enhance collaboration between the healthcare team and the patient. These include effective communication, patient education, including simplifying the treatment regimen (where possible), the use of new technologies, and addressing systemic challenges [23, 24].

Effective communication requires building trust and engaging in shared decision-making, rather than issuing one-sided instructions, which patients often find difficult to understand or impossible to follow due to specialized medical or scientific terminology. In patient education, it is essential to explain the purpose of treatment, the mechanism behind the medication, and potential side effects, as this increases awareness and motivation to take an active role. It is also important that this information is repeated several times (in different contexts), while the feedback from the patient regarding the information provided (so-called clarification) is an indispensable element of effective education.

Another significant factor is the patient’s understanding of the actions they should take as part of their treatment. It is important to remember that simply understanding the meaning of the recommendations will not, in itself, lead to a change in the patient’s behaviour. This is a long-term process based on mutual trust [25]. For example, guidelines on heart failure, obesity treatment, or management of acute coronary syndromes emphasize the importance of patient education, particularly in the areas of treatment, lifestyle changes, symptom monitoring, and appropriate responses to observed changes. Developing practical recommendations for self-care in patients with heart failure, which distinguish between maintaining self-care, monitoring, and managing self-care as well as self-monitoring, is not sufficient to change the patient’s health behaviours [26]. An interesting study on the effectiveness of an innovative self-management programme led by nurses was conducted in Singapore from 2018 to 2019, recruiting 114 patients with heart failure. The programme consisted of a three-month intervention comprising a single face-to-face session, distribution of a brochure and three follow-up telephone calls at weeks 3, 6 and 9. The study was conducted using standardized assessment tools such as self-care, behavioural automatism, and future-oriented thinking. The results of this study clearly demonstrated the effectiveness of the educational intervention in every aspect examined, as it was multifaceted and focused on various areas of the patient’s activity [27].

Another strategy that may improve the likelihood of adherence is the use of a simplified treatment regimen, such as prescribing combination medication (e.g., polypills) and minimizing the number of daily doses. This may increase the patient’s engagement in the process of taking and adhering to medication guidelines, in line with the principle that “medication does not work in patients who do not take it,” as treatment is only as effective as it is actually implemented. Another important strategy may be the use of technology in the treatment process, such as monitoring the fulfilment of e-prescriptions and using digital health tools to facilitate therapy oversight. This aspect may be difficult to implement among older adults who do not use new technologies for various reasons (so-called “technologically excluded” individuals) or those who do not accept digital tools due to a lack of trust in these methods [28-30]. One study conducted a literature review to assess the status of digital educational resources for cardiac patients and the impact of digital patient education on changes in knowledge levels. The assessment included parameters such as the patient’s level of knowledge regarding a healthy lifestyle in the context of cardiovascular disease, as well as levels of anxiety, satisfaction, and depression. This review demonstrated that digital patient education significantly increases knowledge about the disease and healthy behaviours, improves quality of life, and reduces anxiety and depression. Applications for smartphones and tablets, online content, and video content in the form of short videos were found to be the most popular among digital methods [31].

Systemic solutions that facilitate this process (e.g., through the development of digital medicine and centralized e-registration, as well as changes such as the implementation of Advanced Practice Nursing) play a significant role in improving adherence [32]. Public awareness campaigns aimed at promoting the concept of adherence cannot be overstated. Prof. Izabella Uchmanowicz of the Medical University of Wrocław, through campaigns such as #TrzymajSięZaleceń, emphasizes the importance of education, simplifying treatment, and building trust (e.g., in nurses) as tools for improvement in the context of cardiovascular diseases. In this campaign adherence is understood as the patient’s shared responsibility for the treatment process, rather than merely passively taking medication, and consistently following medical, dietary, and physical activity recommendations. It is a process requiring support, education, trust, and collaboration between the patient and the medical team [33].

Adherence assessment tools

There are various standardized research tools validated in Poland that are used to assess adherence levels, providing its objective evaluation. The tools most commonly used by researchers in Poland include:

• Morisky Medication Adherence Scale (MMAS-8),

• Adherence in Chronic Diseases Scale (ACDS),

• Beliefs about Medicines Questionnaire (BMQ),

• Medication Adherence Report Scale – MARS-5,

• Hill-Bone Compliance Scale [34-38].

The Morisky Medication Adherence Scale (MMAS-8) is used to assess adherence to medical recommendations, particularly medication regimens. This scale is also known as the Medication Adherence and Compliance Questionnaire. It was developed to identify barriers to medication use and allows for the measurement of adherence, which is crucial in the treatment of chronic conditions such as hypertension, diabetes, and asthma. The MMAS-8 is a self-report questionnaire designed to facilitate the identification of MMAS barriers and behaviours. It is based on questions regarding daily medication-taking habits, which allows for the assessment of both intentional and unintentional treatment non-adherence. This tool allows healthcare professionals to adjust treatment strategies and educational interventions to improve treatment outcomes and reduce the risk of complications. The MMAS score typically ranges from 0 to 8 points, where a score of 8 indicates full adherence, and a score below 6 indicates low adherence. Interpretation is often based on a division into three groups: high (8 points), moderate (6-7 points), and low (0-5 points) adherence. It is important for doctors to note that lower scores correlate with poorer treatment outcomes and an increased risk of complications, which requires educational interventions or modifications to the treatment plan. The calculation formula for the score is the sum of points from eight yes/no questions, where a positive answer earns 1 point. In daily medical practice, the MMAS serves as a valuable tool for identifying patients at risk of non-adherence, enabling the personalization of treatment strategies and the optimization of chronic disease control [35]. One of the main advantages of this tool is that it is a simple and quick-to-administer questionnaire, allowing for easy interpretation of the results and straightforward comparison of data across international settings. However, its limitations include restrictive copyright protection requiring the purchase of a commercial license, as well as the potential for patients’ responses to be influenced by social desirability bias, whereby respondents may provide answers they believe are more acceptable to healthcare professionals.

Another scale used by Polish researchers to assess adherence in chronic diseases is the Adherence in Chronic Diseases Scale (ACDS). The questionnaire helps to identify individuals at high risk of non-adherence to recommended treatment and identifies the most common causes of non-adherence. This scale consists of 7 questions that address patient behaviours as well as situations and beliefs that may indirectly influence their adherence. To date, the ACDS scale has been used to assess adherence in patients who have had a heart attack, suffer from cardiac arrhythmias, or are at high cardiovascular risk. The tool (assessing the efficacy and safety of de-escalation regimens of new antiplatelet therapy) is applicable in health promotion for patients with other chronic diseases, including those with specific conditions such as multiple sclerosis and type 2 diabetes [36]. For researchers, one of the main strengths of this scale is that it was developed and psychometrically validated in Poland, ensuring that it adequately reflects the specific characteristics of adherence behaviours among Polish patients with chronic conditions. Nevertheless, the instrument is limited by its reliance solely on patients’ self-assessment of their behaviour, which introduces the risk of overestimating the true level of adherence because of self-reporting bias.

Another tool is the Beliefs about Medicines Questionnaire (BMQ), developed by Prof. Robert Horne and adapted into Polish by Karbownik et al. This scale assesses patients’ beliefs about medicines, which are important determinants of adherence behaviour. The questionnaire is divided into two parts: BMQ-Specific and BMQ-General, where the “Specific” section assesses the patient’s opinion of the medications they are currently taking (the need to use them vs. fears of side effects), while the “General” part assesses the overall attitude towards pharmacotherapy (whether medications are perceived as “poison” or as a blessing of science) [37]. One of the principal advantages of this scale is that it enables a comprehensive assessment of the psychological factors underlying non-adherence by evaluating patients’ concerns and beliefs regarding the necessity of their prescribed treatment. However, the instrument is relatively lengthy and requires more complex interpretation. In addition, it measures patients’ cognitive and emotional perceptions of treatment rather than their actual medication-taking behaviour in everyday clinical practice.

The Medication Adherence Report Scale (MARS-5) is a brief and highly practical tool frequently used in primary care. It consists of only 5 questions, which are phrased in a “non-judgmental” manner, thereby reducing the patient’s tendency to provide socially desirable answers (i.e., hiding the fact that they are missing doses). The statements assessed are: “I forget to take my medication,” “I change the dose of my medication on my own,” “I stop taking my medication for a while,” “I skip a dose when I feel better,” and “I skip a dose when I feel worse.” Each question is scored on a scale of 1 to 5 points, with a total score ranging from 5 to 25 points; the higher the score, the higher the level of adherence (compliance with recommendations). A score of 25 points indicates full adherence (the patient reports perfect compliance with recommendations), while a score below 20-21 points is considered low adherence (non-adherence) [38]. One of the principal strengths of this scale is its effective reduction of social desirability bias by employing a non-judgmental question format, thereby facilitating more honest reporting of occasional medication omissions. Nevertheless, its brevity (consisting of only five items) may limit its ability to capture the complex, non-pharmacological determinants of therapeutic barriers, making it less suitable for comprehensive assessment of the underlying causes of non-adherence.

The Hill-Bone Compliance Scale, a tool originally developed to assess patients with hypertension, is used in Poland (validation for Polish conditions was carried out by Uchmanowicz et al.) and in a broader cardiological context as well. The questionnaire measures three areas: medication adherence (8 questions focusing on regularity, forgetfulness, and self-discontinuation of medication), salt restriction (4 questions examining dietary habits critical to the treatment of hypertension), and adherence to follow-up appointments (2 questions assessing the patient’s organization and their interaction with the healthcare system). The patient rates the frequency of a given situation on a 4-point Likert scale: Not at all/Never, Rarely, Sometimes, Always/Often. On the Polish scale, a score of 56 indicates perfect adherence to recommendations in all areas; the lower the score, the more likely it is to indicate a specific problem. A patient may score 8/8 on the follow-up visits subscale but only 10/32 on the medication adherence subscale, which indicates to the doctor where the problem lies, as the patient attends appointments but does not take their medication [39]. A key strength of this instrument is its unique and comprehensive approach, as it assesses not only adherence to pharmacological treatment but also compliance with behavioural recommendations, such as dietary sodium restriction and attendance at scheduled follow-up visits. However, a notable limitation is that the tool was primarily developed for patients with hypertension, which restricts its generalizability and applicability to other chronic disease populations.

It should be emphasized that the selection of an adherence questionnaire in Polish research practice should be tailored to the clinical profile of the target patient population. While the MMAS-8 and MARS-5 scales primarily assess the behavioural aspects of medication-taking, instruments such as the ACDS and Hill-Bone questionnaire encompass the broader context of chronic disease management, including adherence to non-pharmacological recommendations. In contrast, the BMQ serves as a valuable complementary instrument by identifying patients’ psychosocial barriers and treatment-related beliefs. From a holistic perspective, its use contributes to a more comprehensive understanding of adherence within the studied population.

The use of tools in assessing adherence

Research conducted using standardized and culturally validated assessment tools confirms that patients vary in their adherence to medical recommendations, compliance or non-compliance with treatment plans, and their use of healthcare services. The use of standardized research tools to assess adherence also demonstrates that collaboration between the therapeutic team and the patient, including effective communication, improves adherence and can effectively protect against disease progression and complications. To ensure the transparency and methodological rigor of this review, the literature selection process was guided by predefined eligibility criteria, including publication recency, peer-reviewed source status, and direct relevance to the assessment of medication adherence and validated adherence measurement tools.

In one study aimed at assessing adherence to medical recommendations among patients who had undergone heart transplantation (HTX), the total of 66 patients aged 23-76 years who had undergone HTX between one and 18 years earlier were examined, and the Morisky questionnaire was used to assess adherence. It was found that 35% of patients had forgotten to take their immunosuppressive medications, and 41% had forgotten other medications; significantly, 3-6% vs. 21.21-30.3% of patients discontinued their prescribed treatment. It is worth noting that the study participants were post-transplant patients, and the success of the procedure depends on the pharmacological treatment administered following the surgery [40]. Therefore, one of the most important components of a strategy aimed at improving adherence is patient education. A study conducted in five countries (the United Kingdom, Germany, Spain, Italy, and France) by the Working Group on Lifestyle – Cardiovascular Pharmacotherapy and Adherence of the European Society of Hypertension, which included patients diagnosed with hypertension with the average age of 69.6 years, showed that 59.8% of participants reported excellent adherence, and reporting episodes of non-adherence to physicians was low (13% always/often). Female gender and age > 65 years were associated with a lower odds ratio for non-adherence, while depression, stress, family difficulties, negative information about medications, and poor information were associated with a higher likelihood of non-adherence. In the group of people with a high likelihood of non-adherence, the most important factors motivating proper adherence to treatment recommendations were detailed information about the treatment and the consequences of not taking medication, additional information about the condition provided by healthcare professionals and more information included in the consultation record regarding treatment [41].

In a cross-sectional study involving 150 patients (average age over 72 years), adherence to treatment recommendations for hypertension was assessed using the Hill-Bone Hypertension Treatment Adherence Scale (Hill-Bone CHBPTS). The linear regression model used in the analysis showed that the variables such as age, educational level, and living with family were statistically significant in explaining adherence rates. Therefore, there is a need for personalized education for older patients with hypertension who have low educational status and experience a lack of social support, so that they can better understand and adhere to pharmacological treatment for hypertension [42].

In another study aimed at identifying factors influencing adherence and acceptance of the disease in patients diagnosed with diabetic foot, 54 patients undergoing treatment at a surgical clinic or staying in a surgical ward were examined. The study used the AIS (Acceptance of Illness Scale) and ARMS (Adherence to Refills and Medication Scale) questionnaires, demonstrating that the duration of the disease had a significant impact on its acceptance, which, in turn, was strongly associated with adherence to treatment recommendations. As disease acceptance increased, adherence levels decreased. Therefore, it can be concluded that adherence should be monitored regardless of the level of disease acceptance [43].

Adherence to treatment recommendations among older adults with diabetes and coexisting frailty syndrome is crucial for treatment outcomes and prognosis, as it can prevent complications and significantly influence the prevention and reversibility of frailty syndrome. A study assessing the impact of frailty syndrome (FS) on medication adherence was conducted among 175 patients with type 2 diabetes, with a mean age of 70 years. The Tilburg Frailty Index (TFI) and the ACDS questionnaire were used to measure adherence to medical recommendations. It was demonstrated that frailty in older patients with type 2 diabetes influenced adherence to medical recommendations in this group [44].

A scientific study designed to assess the impact of communication between doctors and nurses and their patients (the study included 1,118 patients aged 18 to 85) on the assessment of the quality of healthcare services was conducted in three primary care clinics in the province of Łódź. The study confirmed the dominant influence of doctors’ and nurses’ communication with patients on patients’ trust and satisfaction. A key factor was the medical staff’s display of empathy toward patients and health education, whereas long waiting time for medical appointments significantly reduced patients’ satisfaction with provided healthcare [45].

Summary

Adherence is a process that requires partnership and active participation on the part of the patient, rather than merely passive compliance with recommendations. Healthcare personnel have a legal obligation to educate patients and provide the information necessary for making informed treatment decisions. Non-adherence is influenced by both unintentional barriers, such as cognitive difficulties or the complexity of treatment, and intentional barriers, such as fear of side effects or lack of confidence in the treatment’s effectiveness. Systemic factors also play a significant role: the cost of medications, short visit times in primary care, insufficient health education, and health misinformation on social media. An important element in improving adherence is effective communication based on trust, empathy, and shared decision-making. Digital tools, such as e-prescription monitoring, can support the treatment process, although they are not available to all patients. Public awareness campaigns emphasize the importance of the patient’s active participation in therapy. Adherence assessment tools, such as the MMAS-8, ACDS, BMQ, MARS-5, and Hill-Bone questionnaires, provide valuable support for doctors and nurses and play a key role in the education of medical students. In medical practice, they enable an objective assessment of whether a patient is following recommendations, which is crucial in the treatment of chronic diseases such as hypertension, diabetes, and cardiovascular diseases. By using the results of the scale, doctors can more quickly identify barriers, both intentional (e.g., fears of side effects) and unintentional (e.g., cognitive difficulties) and adjust the treatment plan, simplify the medication regimen, or enhance patient education. Adherence is the foundation of modern medical care and requires the commitment of both the patient and the entire treatment team.

Disclosures

This research received no external funding.

Institutional review board statement: Not applicable.

The authors declare no conflict of interest.