Cardiac self efficacy and Mediterranean diet adherence in patients with coronary heart disease

Abstract

A Mediterranean diet (MD) is an ideal dietary pattern that has favourable effects on the prevention and treatment of coronary heart disease (CHD). Cardiac self-efficacy (CSE), which reflects patients’ confidence in managing their cardiac condition, may be associated with adherence to recommended lifestyle behaviors in CHD patients. Therefore, the purpose of this study was to assess the relationship between CSE and adherence to an MD in patients with CHD. A cross-sectional study was conducted between August 2023 and May 2024 among 296 adults with diagnosed CHD attending An-Najah National University Hospital, Al-Watani Governmental Hospital, and primary healthcare facilities in Nablus, Palestine. Sociodemographic and clinical data were collected. Adherence to the MD was assessed via a 14-item questionnaire, the Mediterranean Diet Adherence Screener. CSE was assessed via Sullivan’s cardiac self-efficacy scale (SCSES), which contains 13 items. This study included 296 individuals with CHD, of whom 55.7% were men and 44.3% were women. The majority of the participants were married (76%), lived with family (84%), and had been diagnosed for five years or fewer (69.6%). The median patient age was 65.0 (58.0–74.0) years. The median overall MD adherence score was 7.00 (interquartile range: 5.00–8.00). The median overall SCSES score was 24.00 (interquartile range: 17.00–33.00). There was a statistically detectable but modest positive correlation between the overall SCSES score and the MD adherence score (r = 0.153, p = 0.008), indicating a small effect size. Higher overall MD scores were obtained for males (p = 0.009). The findings of the multiple linear regression model revealed that being male (p = 0.009) and having high SCSES scores (p = 0.019) were significant factors that contributed to increased adherence to the MD. Most participants moderately adhered to the MD. Adherence to the MD was affected by sex and was positively correlated with increased CSE among patients with CHD. Interventional and sex-specific studies are still needed to establish robust relationships.

Supplementary Information

The online version contains supplementary material available at 10.1038/s41598-026-49941-x.

Introduction

Coronary heart disease (CHD) is a chronic condition and the leading cause of death globally¹, ranking as the second leading cause of death in Palestine according to the Palestinian Ministry of Health in 2021^2–4. As the most prevalent type of cardiovascular disease, CHD is also the primary cause of heart attack¹. It results from an imbalance between oxygen demand and supply to the heart because of inadequate blood flow, which is caused primarily by coronary atherosclerosis. This condition occurs when the coronary arteries, which supply blood to the heart, become narrowed or blocked as a result of a gradual accumulation of fatty substances³. Smoking, hypertension, diabetes, dyslipidemia, obesity, and age are significant risk factors for heart disease^5–9. Implementing dietary management and lifestyle modifications can help control the symptoms and progression of these conditions while improving an individual’s confidence in managing their cardiac health^10,11.

The Mediterranean diet (MD) has emerged as an optimal dietary pattern, offering significant benefits in the prevention and management of CHD^12–14. First described by Ancel Keys in the 1960 s, the MD is characterized by a low intake of saturated fats and animal proteins but is rich in fruits, vegetables, olive oil, whole grains, legumes, nuts, fish, and lean white meats, with moderate consumption of fermented dairy products¹⁵. Key bioactive compounds such as antioxidants, dietary fibre, monounsaturated fatty acids, omega-3 fatty acids, phytosterols, and probiotics have been identified as the primary contributors to the health-promoting effects of the MD¹². Evidence from clinical and observational studies suggests that adherence to the MD reduces inflammation, decreases high-sensitivity C-reactive protein levels, and may decrease the risk of cardiovascular events, including atrial fibrillation^16,17. Furthermore, the MD may provide protective benefits in populations with comorbid conditions such as chronic kidney disease, where cardiovascular risk is elevated¹⁸.

Cardiac self-efficacy (CSE), on the other hand, plays a crucial role in patients with CHD, influencing their understanding of disease progression and management. It can also impact the development of chronic conditions through both patient behaviors and psychological distress^2,19. CSE, which is defined as a patient’s confidence in their ability to perform activities, can be influenced by the symptoms and complications associated with their cardiovascular condition¹⁹.

A review of the literature highlights that CSE and dietary patterns play crucial roles in the progression of CHD, a very common disease with a high mortality rate worldwide and in Palestine^3,20,21. The rationale for this study is based on (1) the cardioprotective effects of the MD, given its nutritional benefits that support cardiovascular health and reduce risk factors for CHD, such as hypertension and dyslipidemia^2,3,22–24, and (2) the growing recognition of CSE and its role in the management of CHD, as it helps to understand how CHD develops, progresses, and is treated.

Specifically, this study aimed to examine patients with CHD for four reasons. First, CHD is the second most common cause of mortality in Palestine. Second, managing this chronic illness requires a multidisciplinary approach that should incorporate lifestyle modifications. Third, in the context of many chronic conditions, increased self-efficacy is associated with improved management. Fourth, CSE may affect adherence to an MD, which has a cardioprotective effect on the management of CHD. Furthermore, the concept of self-efficacy has evolved from a psychological issue to a significant factor that influences how patients manage chronic illnesses and adhere to medications, physical activity, and healthy dietary patterns, including the MD. Research has indicated that higher levels of self-efficacy are associated with better adherence to treatment regimens and healthier lifestyle choices, leading to better overall cardiovascular outcomes. Despite these favourable conditions, there is a notable absence of research examining the connection between CSE and adherence to the MD among individuals with CHD, particularly in Palestine, which is known for its fertile land; abundant fruits, vegetables, and olive trees; and production of high-quality virgin olive oil²³. Therefore, enhancing CSE may play a vital role in increasing adherence to the MD among individuals with CHD in both developed and developing countries. This study aimed to describe MD adherence and CSE levels and to explore their associations with sociodemographic and clinical characteristics among patients with coronary heart disease. Given the cross-sectional nature of the data, the present study primarily adopts a descriptive epidemiological framework, aiming to characterize adherence patterns and explore associations rather than establish causality^25,26.

Methods

Study design

A cross-sectional descriptive correlational study was conducted among patients with CHD between August 2023 and May 2024. The reporting of this cross-sectional study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines²⁷. A STROBE checklist is provided in supplementary materials (Additional file 1).

Settings of the study

The study was conducted at An-Najah National University Hospital (NNUH), Al-Watani Governmental Hospital, and primary health care facilities located in Nablus city in the occupied Palestinian territories.

Sampling method and sample size calculation

Because published data on the association between CSE and MD adherence in patients with CHD are limited, an a priori effect size could not be precisely specified. Therefore, the study sample size was primarily determined pragmatically on the basis of feasibility and recruitment capacity during the study period. Nevertheless, to ensure that the study was adequately sized for correlation analysis, we considered that detecting a small correlation (e.g., r ≈ 0.20), which is commonly reported in behavioral association studies, would require approximately 194 participants at 80% power and a two-sided α of 0.05. We therefore targeted a larger sample and included 296 participants.

Inclusion and exclusion criteria

The sample size was 296 patients. Patients who were 18 years of age or older, lived in Nablus city permanently, had a history of CHD, had undergone coronary revascularization, and had not experienced a myocardial infarction during the preceding six months were included in the study after consenting to participate. Patients with acute and severe conditions that affect their self-efficacy or for whom it was impossible for them to participate in or complete interviews, such as those concerning stroke, uncompensated heart failure, psychological problems, amputated limbs, or chemotherapy, were excluded.

Variables and data collection tools

The data collection form was structured into four sections. The first section collected sociodemographic information from the participants, including variables such as age, sex, place of residence (city, village, or refugee camp), marital status (married, single, widowed, or divorced), educational level (no formal education/illiterate, primary or secondary school, or university), employment status (employed or unemployed), income level (moderate to high or low), and height and weight measurements. Using the Excel tool, we determined each participant’s BMI, which was defined as “weight in kilograms divided by height in meters squared,” and classified them as underweight (< 18.5), normal (18.50–24.9), overweight (≥ 25.0), or obese (≥ 30.0). The second section focused on clinical data related to CHD, including the time since CHD diagnosis in years (< 5, 5–10, > 10) and the total number of medications (< 5, ≥ 5), as the use of many medications, usually five or more, is the most common definition of polypharmacy used to treat different health issues, which might increase the risk of side effects, drug interactions, and poor treatment adherence²⁸. The number of comorbidities (< 3, ≥ 3) is a common cut-off point for defining comorbidities in the medical literature. This threshold is frequently used in studies to assess the impact of multiple health conditions on patient outcomes, healthcare costs, and quality of life^29,30. Smoking status (nonsmokers, current smokers, or ex-smokers) was also added to the questionnaire.

The third section assessed adherence to the MD via a 14-item questionnaire, the Mediterranean Diet Adherence Screener (MEDAS)^22,31–33, in face-to-face interviews with patients. The tool was developed through a Spanish case‒control study on myocardial infarction to analyse the intake of 12 main components consumed and two MD-related eating habits. Each of the 14 items is given a score of 1 point or 0 points, depending on whether the participants are adherent to each component of the MD (1 point) or not (0 points)²². The composite score derived from this tool was used to calculate the relative risk of myocardial infarction, with a score of ≥ 8 indicating greater adherence to the MD^22,34.

Cardiac self-efficacy was evaluated via Sullivan’s Cardiac Self-Efficacy Scale (SCSES), which comprises 13 items^2,35,36. The original version of this scale was in English and underwent a standard translation process into Arabic, followed by back-translation into English by independent bilingual translators to ensure its translational accuracy³⁶. The participants rated each item on a scale from 0 to 4, where 0 represents “not at all confident” and 4 indicates “completely confident”. The scale measures three key dimensions: control symptoms (4 items), control illness (5 items) and maintaining daily functioning (4 items). Formal permission to use the MEDAS was obtained from Professor Miguel A. Martínez-González via email correspondence. SCSES was used in accordance with the original publication for academic research purposes with appropriate citations^35–37. Formal permission to use the scale was obtained from Professor Mark D. Sullivan via email. The MEDAS has demonstrated acceptable internal consistency (Cronbach’s α ≈ 0.75) and construct validity in Mediterranean populations. The SCSES has demonstrated good reliability (Cronbach’s α range 0.70–0.90). In the present study, the Cronbach’s α was 0.91 for the SCSES, demonstrating excellent internal consistency.

A pilot study was conducted with 15 patients to evaluate the feasibility and clarity of the survey questions. These patients were not included in the final analysis. Participants were recruited consecutively during outpatient cardiology clinic visits and inpatient follow-up appointments at the participating hospitals. No recruitment through social media or electronic platforms was conducted. Data collection was carried out by trained medical students, who conducted face-to-face interviews with CHD patients under the ongoing supervision of the research team. The instrument’s face and content validity were confirmed by three experts in biostatistics and research related to the MD.

Ethical considerations and confidentiality

The study protocol was approved on 21 August 2023 by the Institutional Review Board (IRB) of An-Najah National University (Reference No: Med. August. 2023/26) prior to participant recruitment. Additionally, authorization was granted by the relevant Palestinian health authorities. The ethics committee approved the use of verbal informed consent. Since there was no therapeutic intervention in the research and the study participants were considered to be at minimal risk, all patients provided informed verbal consent instead of written consent. Prior to data collection, the patients gave their verbal consent. The interviewer read the consent form in Arabic to each participant, and a copy of the consent form was marked and attached to each data collection form when the participants verbally agreed to participate.

Statistical analysis

The Statistical Package for the Social Sciences (IBM-SPSS) version 23 was used for all analyses in this study. Continuous data are presented as the means with standard deviations and medians with the first (Q1) and third (Q3) quartiles, frequencies (n), and percentages (%). Odds ratios were calculated via a multivariate logistic model that retained the significantly associated variables in the univariate analyses. Pearson’s correlation was applied to test the correlation between the SCSES score and the MEDAS score. To analyse continuous variables, we employed the nonparametric Mann‒Whitney U test for comparisons between two groups and the Kruskal‒Wallis test for comparisons among three or more groups. The Kolmogorov‒Smirnov test was used to assess the normality of the variable distributions. A multiple linear regression model was constructed to determine the factors associated with adherence to the MD, with the SCSES score as the primary independent variable. A multivariable model was used to explore adjusted associations rather than to establish causal relationships. The term ‘multivariable’ regression is used to indicate a model with multiple independent variables predicting a single outcome, which is consistent with the recommended statistical terminology³⁸. Automated stepwise variable selection was avoided because of its potential to introduce bias, inflate type I error, and increase the risk of overfitting, particularly in observational studies with moderate sample sizes. Instead, variables were selected a priori on the basis of clinical relevance and prior literature (including age, sex, income, educational level, number of comorbidities, and CESES scores) to improve model robustness and interpretability^39,40. Variables with p < 0.05 in univariate analyses, along with potential confounding factors, were included in the final model to identify factors associated with MD adherence. Statistical significance was set at p < 0.05. Consistent with recommendations from the American Statistical Association, p-values were interpreted cautiously and reported alongside effect estimates and 95% confidence intervals rather than being used as a strict dichotomous threshold for ‘statistical significance’^41,42. Missing data were minimal (< 2% across all variables), so complete-case analysis was performed (Additional file 1).

Results

Sociodemographic and clinical characteristics of the participants

A total of 296 patients with CHD were included in this study. The median age was 65.0 [58.0, 74.0] years, and the median weight was 80.0 [68.3, 90.0] kg. More than half of the patients were male, and most were married and living with their families. More than two-thirds were overweight or obese, and more than half had diabetes and hypertension. The majority had been diagnosed for five years or less, and most were taking four or more medications.

The detailed characteristics of the patients included in this study are shown in Table 1.

Table 1.

Sociodemographic and clinical characteristics of patients with coronary heart disease.

Variable	Subgroup	Number (%)
		N = 296
Age category (years)	< 45	18 (6.1)
	45–64	122 (41.2)
	65–75	92 (31.1)
	> 75	64 (21.6)
Gender	Male	165 (55.7)
	Female	131 (44.3)
Marital status	Single, divorced, widowed	71 (24)
	Married	225 (76)
Educational attainment	Illiterate	36 (12.2)
	Primary school	68 (23)
	Middle school	49 (16.6)
	High school and above	143 (48.3)
Residency	Refugee camps	33 (11.1)
	Rural	129 (43.6)
	Urban	134 (45.3)
Occupation	Working	189 (63.9)
	Not working	107 (36.1)
Monthly average income (ILS)a	< 2000	198 (66.9)
	2000–5000	88 (29.7)
	˃5000	10 (3.3)
Smoking	Yes	98 (33.1)
	Quit smoking	84 (28.4)
	Never	114 (38.5)
Living status	Alone	44 (14.9)
	With family	251 (84.8)
BMI	Normal	62 (20.9)
	Overweight	105 (35.5)
	Obesity	129 (43.6
Time since diagnosis (years)	0–5	206 (69.6)
	5–10	55 (18.6)
	> 10	35 (11.8)
Number of comorbidities	< 3	203 (68.6)
	≥ 3	93 (31.4)
Number of medications	< 5	93 (31.4)
	≥ 5	203 (68.6)

ILS Israeli Shekel, BMI body mass index.

Descriptive analysis of CSE and adherence to the MD

The median SCSES score was 24.00 [IQR: 17.00–33.00], while the median MD adherence score was 7.00 [IQR: 5.00–8.00]. Our findings revealed that only 9.5% of the patients reported high adherence to the MD, with a total MD score > 10, whereas 63.5% of the participants reported moderate adherence to the MD; the MD score ranged from 6 to 9, and 27% of the participants reported low adherence to the MD, with an MD score < 5. MD adherence as a binary variable was 39.5%, with a total MD score ≥ 8, and 60.5% of the participants had lower adherence, with a total MD score < 8.

Associations between demographic and clinical factors and MD adherence

The results indicated that the only significant association was between MD adherence and sex (p value = 0.002). Age, marital status, educational level, working status, average monthly income, living status, residency status, smoking status, BMI, time since diagnosis, number of comorbidities and number of medications were not significantly associated (p value > 0.05) (Table 2).

Table 2.

Associations between sociodemographic and clinical variables and adherence to the Mediterranean diet among patients with coronary heart disease (N = 296).

Variable	Subgroup	Number (%)	Median (Q1-Q3)	Mean rank	P value1
Age category (years)	< 45	18 (6.1)	8.00 (5.75–8.25)	169.56	0.2792
	45–64	122 (41.2)	7.00 (5.00–9.00)	156.23
	65–75	92 (31.1)	7.00 (5.00–8.00)	142.21
	> 75	64 (21.6)	6.00 (5.00–8.00)	136.88
Gender	Male	165 (55.7)	7.00 (6.00–9.00)	161.95	0.002 3
	Female	131 (44.3)	6.00 (5.00–8.00)	131.56
Marital status	Single, divorced, widowed	71 (24)	6.00 (5.00–8.00)	137.68	0.2172
	Married	225 (76)	7.00 (6.00–8.00)	151.91
Educational attainment	Illiterate	36 (12.2)	6.00 (5.00–8.00)	135.15	0.4882
	Primary school	68 (23)	7.00 (5.00–8.00)	140.05
	Middle school	49 (16.6)	7.00 (5.00–8.00)	156.39
	High school and above	143 (48.3)	7.00 (5.00–8.00)	153.17
Residency	Refugee camps	33 (11.1)	6.00 (5.00–7.00)	121.77	0.1352
	Rural	129 (43.6)	7.00 (5.00–8.00)	148.95
	Urban	134 (45.3)	7.00 (5.00–8.25.00.25)	154.65
Occupation	Working	189 (63.9)	7.00 (5.00–8.00)	144.89	0.3303
	Not working	107 (36.1)	7.00 (6.00–8.00)	154.87
Monthly average income (ILS) a	< 2000	198 (66.9)	7.00 (5.00–8.00)	145.63	0.7882
	2000–5000	88 (29.7)	7.00 (6.00–8.00)	152.92
	˃5000	10 (3.3)	6.00 (5.00–9.00)	152
Smoking	Yes	98 (33.1)	7.00 (6.00–9.00)	157.83	0.3632
	Quit smoking	84 (28.4)	7.00 (5.00–8.00)	147.38
	Never	114 (38.5)	7.00 (5.00–8.00)	141.31
Living status	Alone	44 (14.9)	6.00 (5.00–8.00)	129.73	0.1193
	With family	251 (84.8)	7.00 (5.00–8.00)	151.2
BMI	Normal	62 (20.9)	7.50 (5.00–9.00)	159.45	0.2282
	Over weight	105 (35.5)	6.00 (5.00–8.00)	137.73
	Obesity	129 (43.6	7.00 (5.00–9.00)	152
Time since diagnosis (years)	0–5	206 (69.6)	7.00 (5.00–8.00)	150.68	0.7772
	5–10	55 (18.6)	7.00 (5.00–8.00)	145.18
	> 10	35 (11.8)	6.00 (5.00–8.00)	140.87
Number of comorbidities	< 3	203 (68.6)	7.00 (5.00–8.00)	152.61	0.2173
	≥ 3	93 (31.4)	6.00 (5.00–8.00)	139.53
Number of medications	< 5	93 (31.4)	7.00 (5.00–8.00)	152.84	0.5513
	≥ 5	203 (68.6)	7.00 (5.00–8.00)	146.51

ILS Israeli Shekel, BMI body mass index.

^a1 US dollars = 3.69 ILS.

¹Bold values denote statistical significance at the level of p < 0.05.

²Kruskal‒Wallis test.

³Mann‒Whitney test.

Correlation between overall SCSES score and MD adherence score

There was a statistically significant, modest positive correlation between the SCSES score and MD adherence score (r = 0.153; p = 0.008).

Multiple linear regression analysis

A multiple linear regression model was constructed to examine factors associated with MD adherence scores. After adjustment for age, income, educational level, and number of comorbidities, male sex and cardiac self-efficacy remained significant predictors of adherence. Female sex (relative to male sex) was associated with lower adherence scores (B = − 0.628, p = 0.009), indicating that male participants had significantly higher MD adherence scores. In addition, higher cardiac self-efficacy scores were independently associated with higher adherence scores (B = 0.025, p = 0.019) (Table 3).

Table 3.

Factors associated with adherence to the Mediterranean diet among patients with CHD.

Variables	Unstandardized Coefficients		Standardized Coefficients	t	P value1	95% Confidence interval for B
	B	Std. Error	Beta			Lower bound	Upper bound
Constant	7.044	0.473		14.877	< 0.001	6.112	7.975
Gender	−0.628	0.239	−0.151	−2.623	0.009	−1.098	−0.157
Cardiac self-efficacy	0.025	0.011	0.136	2.366	0.019	0.004	0.047

¹Bold values denote statistical significance at the level of p < 0.05.

Cardiac self-efficacy was modelled as a continuous variable. The regression coefficient (B) represents the change in the Mediterranean diet adherence score per-point increase in the SCSES score. The model was adjusted for age, sex, income, educational level, and number of comorbidities.

Discussion

This study investigated the sociodemographic and clinical characteristics of patients with CHD, examined adherence to the MD, and explored the association between CSE and MD adherence. The high prevalence of overweight and obesity, as well as comorbid conditions such as diabetes and hypertension, reflects the substantial cardiovascular risk burden in this population. Despite the well-established cardioprotective effect of the MD^18,43,44, adherence was generally suboptimal, with a small proportion of patients demonstrating good adherence. Consistent with reports from several Mediterranean and non-Mediterranean populations, moderate to low adherence to the MD remains common even in regions where elements of this dietary pattern are culturally familiar^23,45–47. These findings suggest that cultural familiarity alone does not guarantee adherence. Structural and economic factors, food accessibility, and local food ecosystems may influence dietary behaviors⁴⁸. Studies have shown that shorter supply chains, often featuring fresh local products, are associated with better management of metabolic syndrome and healthier diets^48,49. In the Palestinian context, components of the MD are culturally familiar. However, economic constraints and food insecurity may limit access to specific items, suggesting that lower adherence may reflect structural limitations rather than behavioural preference alone.

Although many people assume that heart conditions are diseases of men, CHD and stroke remain the leading causes of morbidity and mortality among women worldwide for many reasons that may be related to low adherence to the MD^50,51. While previous studies have reported mixed results regarding sex differences in dietary adherence, a notable finding was the significant association between male sex and greater MD adherence in the present study. Our findings suggest that gender-related social roles and cultural expectations may partly influence dietary behaviors^23,52. While the observed sex difference may reflect unmeasured social and domestic factors, such as household food preparation roles or caregiving responsibilities, which were not directly measured in this study, future research is needed to clarify whether sex differences in dietary adherence and self-efficacy contribute to differences in clinical outcomes among CHD patients. Women with CHD may experience lower perceived health status or reduced CSE, potentially influencing their ability to adopt and maintain dietary modifications^{18,23,52–54}. For example, women often assume caregiving roles, which may limit the time or resources available for managing their own health, including adherence to the MD⁵⁵. Differences in emotional well-being, symptom perception, and access to healthcare resources may also contribute to disparities in adherence behaviors between men and women. Although this study did not assess clinical outcomes such as mortality, the observed lower adherence among women may have potential implications for long-term cardiovascular risk. These findings underscore the importance of considering sex-sensitivity approaches when dietary interventions are designed. These results may be related to the low level of CSE, psychological pressure, and lack of social support that women experience around the world, including in the Palestinian Territories^2,56–58.

Additionally, social norms and conventional gender roles may affect dietary practices in certain cultures⁵⁹. For example, compared with women, men may have distinct social dynamics in regard to food purchases, making them more exposed to Mediterranean-style meals (such as fish and olive oils), which may make adherence easier, causing males to adopt a Mediterranean-style diet and becoming even more open to drastic nutritional changes; thus, compared with women, these individuals can experience pressure to follow different dietary guidelines. In addition, men tend to be more exposed to short-chain food and eat more fruits, vegetables, and healthy fats, which improves adherence levels overall. Men may also be more inclined to take risks, which may spread to their eating habits, leading them to adopt new eating habits as a management strategy against heart disease. This study supports evidence from a previous study indicating that men may demonstrate greater adherence to the MD under certain clinical conditions⁵². Thus, it is essential to consider the variability in findings across different populations and cultural backgrounds.

Another notable finding of our study is that higher SCSES scores were independently associated with improved MD adherence⁶⁰. These findings support the theoretical framework suggesting that individuals with greater self-efficacy are more likely to adopt health-promoting behaviors, including dietary modifications. These results underscore the importance of addressing both psychological and sociodemographic factors when interventions are designed to improve MD adherence among patients with CHD. Although the association between cardiac self-efficacy and MD adherence was statistically detectable, the magnitude of the correlation was small (r = 0.153), suggesting that self-efficacy explains only a limited proportion of the variability in dietary adherence; therefore, emphasis should be placed on effect size and precision rather than solely on p values⁴¹. Therefore, additional behavioral, social, and structural determinants likely contribute to adherence patterns. “Self-efficacy”, which is a psychological term coined by Albert Bandura, describes a person’s belief in his or her capacity to carry out tasks and accomplish objectives⁶¹. CSE, on the other hand, refers to an individual’s confidence in controlling their condition, following treatment regimens, and continuing cardiovascular health-promoting habits such as exercising, eating healthy and quitting smoking^62–64.

However, given the cross-sectional design, temporality cannot be established. Therefore, the observed association between CSE and MD adherence should be interpreted as correlational rather than causal. It is also plausible that adherence to healthy dietary practices enhances perceived self-efficacy, indicating a potentially bidirectional relationship. These findings should be interpreted cautiously given the cross-sectional design and the use of a brief dietary screening tool rather than comprehensive dietary assessment methods. Future longitudinal studies using repeated dietary measurements and objective biomarkers may help clarify the temporal and causal nature of the relationship between self-efficacy and dietary adherence.

Strengths of the study

This study has several strengths. First, it focused on patients with CHD, the second leading cause of death in Palestine, which ensures the clinical relevance of the study. Second, data collection was cost-effective, as patients referred from primary healthcare facilities, including Al-Watani Hospital and An-Najah National University Hospital, as well as cities, refugee camps, and villages, were included. Third, this is the first study to evaluate how CSE affects CHD patients’ adherence to the MD. Finally, the sample size is adequate to allow for the identification of the various factors influencing adherence to the MD, and the findings may provide insight into CHD patients in similar clinical settings.

Limitations of the study

This study has several limitations. First, its cross-sectional design prevents causal inferences between CSE, MD adherence, and associated factors. Second, the data were self-reported, making them susceptible to recall and social desirability bias. Dietary assessment tools are particularly prone to systematic measurement error, which may attenuate associations or bias estimates in unpredictable directions. Validation studies using recovery biomarkers have demonstrated that dietary self-report instruments may substantially misestimate true intake levels^65,66. Third, the use of convenience sampling (a nonrandom method) and recruitment from a single governorate limits the representativeness of the sample and generalizability of the findings. Fourth, the absence of a control group precluded direct comparisons with non-CHD individuals. Finally, although the current sample size was adequate for this analysis, larger, more diverse samples in future studies would improve generalizability, reduce bias, and enhance the accuracy of the findings. Future research, particularly case‒control or cohort studies, is needed to better understand the factors influencing MD adherence among patients with CHD.

Conclusions

Adherence to the Mediterranean diet among patients with CHD was modestly associated with sex and CSE. However, owing to the cross-sectional design, causal inferences cannot be drawn. The modest magnitude of the correlation suggests that multiple behavioral, social, and economic factors likely contribute to dietary adherence. Understanding the interplay between these factors is essential for designing effective interventions that can alleviate the burden of heart disease. Healthcare providers, particularly cardiologists and clinical dietitians, should consider these associations when developing more targeted, sex-specific interventions to promote adherence to the MD among CHD patients as well as those at risk of the condition.

Recommendations

1. Healthcare providers should consider patients’ adherence to the MD when evaluating cardiovascular risk, as it can be a superior dietary intervention for preventing CHD-related events.

2. Interventions aimed at improving CSE can enhance adherence to healthy dietary patterns. Programs that develop patients’ confidence and skills in meal planning, preparation, and lifestyle modifications should be incorporated into routine care.

3. Tailored strategies, including dietary counselling, behavioral therapy, workshops and skill-building programs in meal planning and preparation, should address the distinct needs of men and women and maximize MD adherence and improve patient outcomes.

4. Future studies should employ longitudinal studies or interventional studies to clarify the causal relationships between CSE, sex, and adherence to an MD in CHD patients. Research should involve participants from different cultural, social, and demographic backgrounds to examine how these factors influence dietary adherence and self-efficacy, allowing interventions to be adapted for wider populations.

Supplementary Information

Below is the link to the electronic supplementary material.

Abbreviations

MD

Mediterranean diet

CHD

Coronary heart disease

SCSES

Sullivan’s Cardiac Self-Efficacy Scale

CSE

Cardiac self-efficacy

SPSS

Statistical Package for the Social Sciences

IRB

Institutional Review Board

BMI

Body mass index

MEDAS

Mediterranean Diet Adherence Scale

NNUH

An-Najah National University Hospital

IQR

Interquartile range

Author contributions

Shakhshir MH designed and supervised the study, analysed and coordinated the data, participated in the interpretation of the results, made significant contributions to the search and interpretation of the literature, critically revised the manuscript for important intellectual content, responded to the reviewers’ comments, and wrote the final version. Khalel KK, Fakhoury HT, and Hamuda LK reviewed the literature, collected the data, performed the analysis, and wrote the first draft of the manuscript. Zyoud SH supervised the field study, provided methodological guidance, ensured the integrity and rigor of the analysis, critically reviewed the manuscript for clarity and scientific accuracy, responded to the reviewers’ comments, and edited the final draft. Abu Taha A and Ismail Y offered logistical support, assisted in data interpretation, and produced the final version of the manuscript. All the authors reviewed and accepted the final manuscript.

Funding

There is no funding source for this research.

Data availability

The data, materials and details of the statistical analysis procedures used in this study are available from the corresponding authors upon reasonable request.

Declarations

Competing interests

The authors declare no competing interests.

Ethics approval and consent to participate

The study protocol was approved on 21 August 2023 by the IRB of An-Najah National University (Reference No: Med. August. 2023/26) prior to participant recruitment. The NNUH Research Center and local health authorities approved the study plan, which included access to and use of patient clinical data. An-Najah National University’s IRB permitted verbal informed consent because participants were only required to participate in the interviews, and no harm was anticipated as long as their privacy was protected. Informed consent was obtained from all participants and/or their legal guardian(s). The authors confirm that all procedures comply with applicable regulations and guidelines to ensure the safety and protection of participants. The study adhered to the principles of the Helsinki Declaration and the European standards for good clinical practice.