Cardiometabolic Patient-Related Factors Influencing the Adherence to Lifestyle Changes and Overall Treatment: A Review of the Recent Literature

It is well acknowledged that most of the modifiable risk factors for Cardiovascular Diseases (CVDs) can be averted through lifestyle modifications beyond medication adherence. This review aims to critically evaluate the cardiometabolic (CM) patient-related factors that influence the adherence to lifestyle changes studied alone and/or in combination with medication. A comprehensive literature search of PubMed articles from 2000 to 2023 retrieved 379 articles. After removing the articles which were not relevant, a total of 28 cross-sectional studies was chosen (12 qualitative, and 16 quantitative). The findings confirmed that five groups of factors influence patients’ adherence to overall treatment: (1) health beliefs, knowledge, and perceptions regarding the risks and challenges of disease and medication intake along with adherence process perceptions; (2) self-concept; (3) emotions; (4) patient–healthcare providers relationship/communication and (5) social and cultural interactions. It is worth mentioning that cultural issues, such as culinary particularities, ethnic identity, social life as well as patients’ skills and abilities, play a profound role in the effectiveness of the recommended lifestyle modifications beyond the aforementioned common factors. The need for clear-cut culturally adapted guidelines along with personalized advice from physicians is imperative as it could improve patients’ self-efficacy. These socio-psychological factors should be seriously considered as a means to increase the effectiveness of future community prevention programs.


Introduction
Cardiometabolic diseases [CMDs, i.e., cardiovascular disease (CVD), type II diabetes mellitus, dyslipidemia, hypertension, and obesity] are one of the leading causes of mortality globally and continue to constitute a major public health problem [1].
Although the diagnosis of CMDs is not considered complicated, the effectiveness of the treatment is rather low due to patients' compliance/adherence. When talking about "compliance" or "adherence" it should be clarified that even though these terms are used interchangeably, "compliance" has a more negative connotation, as it implies a passive behavior from the patient's side, where the patient has to oblige to the rules. On the other hand, "adherence" is defined as the extent to which an individual's behavior aligns with the recommendations from the health care provider, indicating a patient's active involvement in which both doctor and patient work together [2][3][4][5].

Search Strategy
We focused on the most recent publications, only including manuscripts published after the year of 2000. For the present review, studies published in peer-reviewed journals in the English language were selected from the electronic database of PubMed via a systematic search. Studies published from 1 January 2000 up to 10 April 2023 were included. An advanced search string was developed for the selection of the articles: ("perception*" OR "belief*" OR "self-efficacy" OR "behavior*" OR "awareness" OR "emotion*" OR "feeling*" OR "knowledge" OR "experience*" OR "self-care" OR "barriers" OR "facilitators" OR "psychological" or "social" OR "financial" OR "psychosocial") AND ("adherence" OR "compliance" OR "persistence") AND ("cardio metabolic diseases" OR "CVD" OR "cardiovascular diseases" OR "cardiovascular risk factors") AND ("recommendations" OR "treatment" OR "advice*" OR "change*") AND ("lifestyle" OR "diet*" OR "physical activity" OR "habit*" OR "smoking" OR "health behavior*" OR "medication" OR "drug*") AND ("qualitative*" OR "questionnaire*" OR "survey*" OR "interview*"). Figure 1 depicts the flow chart of the selection process of the literature search. PubMed indicated a total of 379 studies. After an initial screening of the title and the abstract, non-relevant articles were removed and finally a total of 138 studies were selected for the review in our paper. Next, we conducted a thorough scrutiny by reading the full papers and according to the inclusion criteria, 15 studies were finally retained [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Additionally, non-relevant articles were removed and finally a total of 138 studies were selected for the review in our paper. Next, we conducted a thorough scrutiny by reading the full papers and according to the inclusion criteria, 15 studies were finally retained [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Additionally, 13 more eligible studies were identified through manual screening, and therefore the total number of studies were 28 [37][38][39][40][41][42][43][44][45][46][47][48][49]. Papers underwent three phases of screening (titles, abstracts and full papers). Two reviewers (V.K. and V.B.) independently selected the studies, and a third researcher (R.I.K.) was consulted in order to rectify any discrepancies. Whenever the inclusion of a study was not clear, the three researchers discussed it collectively to make the final decision, keeping in mind the inclusion and exclusion criteria. All studies included were read in full by the three researchers.

Inclusion and Exclusion Criteria
We were primarily interested in factors affecting adherence or non-adherence to lifestyle recommendations from the patients' perspective. Secondly, we aimed to identify patients' viewpoints on overall adherence (lifestyle and medication). Inclusion criteria involved: (i) adults (>18 years) with CMDs or being at risk of CMDs, either self-reported or diagnosed; and (ii) a clearly defined exposure including the knowledge, awareness, beliefs, perceptions, feelings, behaviors, emotions and self-efficacy to the recommended therapeutic regimen, with an outcome related to the adherence or compliance or persistence to lifestyle changes (diet, physical activity, alcohol consumption, and smoking), and/or in combination with medication intake. Ultimately, the studies were assessed for their relevance to the aims of our review. Papers underwent three phases of screening (titles, abstracts and full papers). Two reviewers (V.K. and V.B.) independently selected the studies, and a third researcher (R.I.K.) was consulted in order to rectify any discrepancies. Whenever the inclusion of a study was not clear, the three researchers discussed it collectively to make the final decision, keeping in mind the inclusion and exclusion criteria. All studies included were read in full by the three researchers.

Inclusion and Exclusion Criteria
We were primarily interested in factors affecting adherence or non-adherence to lifestyle recommendations from the patients' perspective. Secondly, we aimed to identify patients' viewpoints on overall adherence (lifestyle and medication). Inclusion criteria involved: (i) adults (>18 years) with CMDs or being at risk of CMDs, either self-reported or diagnosed; and (ii) a clearly defined exposure including the knowledge, awareness, beliefs, perceptions, feelings, behaviors, emotions and self-efficacy to the recommended therapeutic regimen, with an outcome related to the adherence or compliance or persistence to lifestyle changes (diet, physical activity, alcohol consumption, and smoking), and/or in combination with medication intake. Ultimately, the studies were assessed for their relevance to the aims of our review.
Studies were excluded if the exposure and/or outcome did not meet the criteria and if the outcome was only related to adherence to medical prescription. Studies including patients with mental illness were also excluded, along with institutionalized patients, patients in rehabilitation centers, patients that are currently being hospitalized, patients with an acute illness or patients who were pregnant or drug/alcohol users. Clinical trials/intervention studies, reviews, systematic reviews, and meta-analyses were also excluded from this review.

Data Extraction
The following relevant data were extracted from each of the selected studies: first author/year of publication, country, type of study, population characteristics (number, sex, age, and condition), objectives of the study, type of adherence to the treatment assessed, data collection tools and outcomes.
The sample size of the included studies ranged from 20 [43] to 2870 [27] participants. In all the studies, patients were over 18 years old and of both sexes, except one study which included only males [48].
All above data are clearly outlined on Table 1.

Adherence to Overall Treatment (Both Medication and Lifestyle Changes)
Several studies in the present review [23,25,27,29,30,41,42,44,45,[47][48][49] indicated that higher adherence to overall treatment was related with greater knowledge and positive health beliefs, perceptions and emotions regarding disease and medication risks.
In particular, authors [27][28][29]41,47] concluded that the higher the knowledge of the patients, the higher the adherence to the recommendations for the successful management of the disease. Patients' knowledge, education, motivation and psychological state were also highly associated with treatment attitudes and adherence [42]. More specifically, psychosocial factors, such as depression, anxiety, fear of addiction and intolerable/adverse drug effects, were associated with patients' negative attitudes to treatment [42]. Moreover, the higher the significance that patients attribute to medication, diet and exercise, the higher the adherence to treatment regimens [49]. Similarly, in the study of Walker et al. fatalistic beliefs were shown to act as barriers to the overall effective diabetes management, [44] demonstrating that perceptions of despair, hopelessness and powerlessness contribute to low adherence to physical activity. Furthermore, illness acceptance was another crucial factor related to adherence to non-pharmacological therapy [47].
Several studies [23][24][25][26][27][28]39,43,48,49] showed that a positive self-concept as related to several other "self" constructs including self-efficacy, self-esteem, and self-consistency improve overall adherence. "Self-concept is an overarching idea we have about who we are-physically, emotionally, socially, spiritually, and in terms of any other aspects that make up who we are" [50]. Self-efficacy was concluded by Chiou et al. to be the strongest predictor of improving adherence to overall treatment recommendations [23]. Moreover, Heydari et al. indicated that higher adherence depended on higher self-consistency to the daily healthy recommended routine and on patients' view on self-concept, including body image [24]. In other words, when self-concept is perceived as a challenge, patients tend to adhere to the therapeutic recommendations, while when it is perceived as a threat, patients do not tend to adhere. Similarly, Thomas found that health regimens that are perceived by participants as threatening to self-concept result in emotionally centered responses and non-adherent behaviors [39]. Herrera et al. also indicated that high self-esteem, autonomy, well-being and sense of freedom are correlated with higher adherence [49]. It is worth mentioning that the study of Hardcastle et al. found that patients' low adherence to lifestyle behavioral changes was attributed to low self-control [25]. In the study of Singh et al., almost all participants felt that adherence to dietary restrictions was very strenuous [43]. In other words, as the lack of perceived control of the study participants decreased, the feelings of weakness and engagement in unhealthy behaviors enhanced [48]. Similarly, Sarfo et al. postulated that the higher the control of the disease, the higher the adherence to medication and recommended salt cessation [27].
As regards to the social aspect of the patient-related factors, findings from the present review stressed that positive social interactions, both with physicians and with the close family environment, enhance healthy long-term behavioral changes. In particular, social support, positive healthcare experiences and the core role of family have been revealed as facilitators in the adherence process [26,[28][29][30]43,48]. Social and cultural pressures, such as community social etiquettes, result in families trying to conceal the disease and therefore leading to patients compromising their treatment and health as a means to avoid social stigma. Furthermore, the perceived positive impact of religion in terms of patients' perceptions of receiving support from prayers, along with a lack of support from the healthcare providers have been identified as barriers to medication adherence [43]. Similarly, in another study [28] authors concluded that low adherence was attributed to the lack of trust on physicians' knowledge, as well as the influence of culture and traditions on the family meals, making it difficult for some family members to follow a healthier diet [28].

Adherence to Recommended Lifestyle Changes (Exclusively Studied)
As regards to the patient-related factors influencing the adherence to recommended lifestyle changes, findings [22,[31][32][33][34][35]37,38,40,45,46] postulated that knowledge, positive beliefs, high self-efficacy, support from friends and family along with trust on the physicians' knowledge and ability to provide clear-cut culturally adapted guidelines and advice seem to play the most influential and beneficial role.
More specifically, the power of positive health beliefs and perceptions along with proper knowledge on what constitutes healthy lifestyle choices, the reasoning and rationalization of the necessity for the adoption of healthy lifestyle habits and their impact on the disease outcome have been revealed as the factors influencing adherence in several studies [31,[34][35][36][37][38]40,46]. On the other hand, lack of information related to healthier cooking of traditional dishes and time devoted to meal preparation constitute notable barriers to leading a healthier life [22,32,37].
Self-efficacy in the adherence process has been also found to play a substantial role [22,33,38]. Specifically, low self-efficacy was a great barrier to following physical activity recommendations [33] along with limited time management skills [38]. Participants declared that even though they were well aware of the benefits and the necessity of exercising, they did not have the personal ability to make the change, while most of them preferred to take medications [33]. Another study showed that patients' unwillingness along with their difficulty in adhering to a diet different from that of the rest of the family were found to be the barriers to the recommended lifestyle changes [22].
It is worth mentioning that socio-cultural factors [22,33,34] were revealed to be a significant determinant in the adherence process. More precisely, social gatherings and cultural issues, such as culinary particularities along with the high frequency of social events, were reported as the main barriers to diet adherence [22]. Lack of culturally appropriate advice regarding foods that hold a cultural and social importance aggravate patients' ability to follow their dietary treatment [34]. The perception of a fixed and unchangeable ethnic identity that is linked with unhealthy behaviors, such as unhealthy dishes, has also been denoted by patients as a barrier that they cannot overcome [33].
In the present review, the fundamental role of patient-healthcare provider relationship/communication [32,33] has also been highlighted. Findings indicated that low adherence was correlated with dissatisfaction emerged from feelings that the consultation was insufficient, non-satisfactory relationship and communication with the health professional along with feelings of embarrassment in the professional's presence [32], as well as lack of patients' trust on physicians [33]. In other words, when patients feel that their doctor lacks knowledge, communication skills and does not properly explain the plan that needs to be followed, they feel unsatisfied and therefore they believe that their health problem cannot be tackled [33].

Discussion
This review aims to critically evaluate, for the first time, the cardiometabolic (CM) patient-related factors that influence the adherence to lifestyle changes and overall treatment. In the present work, some major influential factors of adherence and non-adherence with regards to lifestyle changes, or the combination of both lifestyle changes and drug recommendations have been highlighted. There are commonalities found in many studies on this review, regardless of the country the study took place in or the risk factor/disease studied. In particular, the findings of this review confirmed that five groups of factors influence patients' adherence to treatment: (1) beliefs, such as knowledge, perceptions in terms of the adherence process, along with risks and challenges of disease/medication intake and health; (2) self-concept; (3) emotions; (4) patient-healthcare providers relationship/communication and (5) social and cultural interactions.
These socio-psychological factors should be seriously considered as a means to increase the effectiveness of future community prevention programs. The above mentioned factors have already been well-reported in a recently published review exclusively evaluating medication adherence from the patient's perspective in chronic diseases [51].
Knowledge has been shown to be a common denominator for adherence both in terms of lifestyle changes and medication. Findings postulated that patients' knowledge and accurate perception of the adherence process is of utmost importance. In order for the patient to acquire the proper knowledge, a good relationship with the healthcare provider needs to be established [52].
Communication is one of the pillars in the patient and healthcare provider relationship. Great communication creates an honest environment that is based on trust, where patients do not feel judged or embarrassed by the clinicians. It is of great importance that healthcare providers demonstrate empathy towards patients and provide health education by translating science into concise, sound lifestyle and nutrition-based guidance. Moreover, it can be relied upon the patient to make dietary choices, along with proper medicine intake whenever prescribed, which will ultimately lead to a healthy routine and a healthy life [53,54].
Patients' trust in the knowledge of the healthcare providers is also very important, as it makes patients feel safe. The suggested guidelines will assist with the management of their disease, which will further motivate and provide confidence to the patients [55]. The psychological support that patients receive can raise their self-efficacy and help with self-management and self-discipline. This also includes support from family and friends that makes individuals feel empowered and motivated to lead a healthy life. In fact, peer influence, social stigma, lack of support from family, friends and healthcare personnel can even become stress factors and further decrease the patient's ability or willingness to comply [56,57].
Lack of knowledge induces negative emotions with ambiguous effects, thus influencing the adherence process. This could be possibly due to fear of failure, fear of not achieving the desired outcome, or even due to concerns over medication side-effects [51,58,59]. Research has indicated that participants who postpone the thoughts of consequences, belittle the treatment and avoid unnecessary interference, have a higher likelihood to not adhere to the healthy lifestyle [60]. In particular, Urke et al. concluded that personal achievements resulting from engaging in self-management behaviors, specifically, exercise, dietary changes, medication adherence and smoking cessation, along with the close relationship with family were perceived as facilitators in the adherence process [60]. On the other hand, distrust in the medications and pharmaceutical companies as a result of the side-effects have been perceived as barriers to the medication adherence. However, despite this low medication adherence, patients expressed their willingness to increase their engagement in healthy lifestyle behaviors. Beliefs, such as the restriction of desired food groups, were perceived as a compromise in the quality of life and thus dietary restrictions were perceived as a barrier to lifestyle adherence. Wrong beliefs, such as weakness and vulnerability, are induced as a result of having a chronic disease and therefore deteriorate the adherence [60].
On the other hand, fear due to the perceived seriousness of the disease can lead to positive reinforcement towards better adherence [52].
Research has shown that diabetic patients perceive dietary restrictions as challenging to self-management, leading to negative emotions, such as frustration, depression, and anger, enhancing poor dietary self-care and thus creating a vicious cycle of poor dietary adherence and negative emotions [61]. Amankwah-Poku concluded that the apparent wavering nature of patients in regard to dietary adherence could be tackled through realization of the importance of dietary adherence, implying the crucial role of knowledge in the adherence process [61]. This finding has been consistently demonstrated in the present review. It is the patients' illness perception, beliefs and awareness of the positive and negative impact of their medication along with their knowledge of the impact on their lifestyle behavior that determines their copying behavior and therefore their adherence and disease outcome [62]. Indeed, research has demonstrated that health regimens that are perceived by participants as threatening to self-concept result in emotionally centered responses and non-adherent behaviors [39].
Regarding lifestyle changes and more specifically dietary changes, it is worth mentioning that these are inextricably linked with cultural, religion and ethnic identity factors. This can be challenging for the healthcare provider, as it automatically means that they need to conduct an accurate screening of the patients profile in order to identify secondary or hidden beliefs and avoid providing culturally inappropriate advice. This means that they should also be well-aware and knowledgeable regarding the cultural norms in order to help patients overcome the fear of stigma deriving from social and cultural pressures, and thus create a tailored therapeutic protocol that will be feasible for the individual to adapt in their daily routine [63,64].
Moreover, results showed that there may be a bidirectional association between lifestyle and medication adherence in regard to the perceived seriousness of the disease and/or the patient's beliefs. In particular, studies [25,60] showed that distrust of medication may increase lifestyle changes adherence, while on the other hand, the lower the perceived seriousness of the disease, the lower the adherence to lifestyle changes because patients feel that the disease could be effectively managed through medication. This observation is of utmost importance because it underlines the need for proper education delivered to both physicians and patients, highlighting that the synergistic effect of both medication and lifestyle modifications has been proven to be the most effective for disease management.
Nevertheless, it must be acknowledged that this review has several limitations. Firstly, no assessment of the included studies' quality has been performed, which have perhaps jeopardized the validity of the findings. Moreover, there is heterogeneity between studies as regards to the size of the sample, the outcome, the age range, the assessment tools used and the location and thus no direct comparisons could be performed. It is worth mentioning that even though the vast majority of the studies were conducted in different world parts, several commonalities in influential factors have been identified. Lastly, only the PubMed database was searched, a fact which could probably limit the extent of the identified patient-related factors influencing the adherence to lifestyle changes and overall treatment of CMDs. However, many common barriers and facilitators have been stated in various studies, meaning that the possibility of missing information is limited.

Conclusions
Patients' beliefs and perceptions, self-concept, emotions, as well as patient-healthcare provider relationship and patient social interactions appear as the catalytic components of the overall treatment adherence, acting as key factors for the successful management and tackling of CMDs. It is worth mentioning that cultural issues, such as culinary particularities, ethnic identity, and social life along with skills and abilities seem to play a profound role on lifestyle modifications beyond the other common factors. The need for clear-cut culturally adapted guidelines along with personalized advice from physicians is evident as it could improve patients' self-efficacy.
These socio-psychological factors could provide the foundation for the design and implementation of future community prevention studies regarding lifestyle modifications in order to alleviate the burden of CMDs.