Coronary artery disease, which is characterised by high morbidity, mortality and recurrence rates and multiple complications, is one of the most prevalent chronic diseases and the leading cause of death from chronic non-communicable diseases worldwide, with its incidence, recurrence, mortality and disability-adjusted life year rates only increasing every year [1]. Estimates by the American Heart Association have shown that around 19.1 million people die of cardiovascular disease annually, the most common of which is coronary artery disease, which has a global incidence of approximately 240 million, as well as a high recurrence rate [2]. The prevalence of coronary artery disease has continued to increase every year. Estimates show that the number of current patients with cardiovascular disease in China is around 330 million, 11.39 million of whom have coronary artery disease [3], and that mortality rates have been on the rise since 2012.

Patients with coronary artery disease commonly suffer from psychological problems, which may negatively affect their quality of life and treatment outcomes [4]. Mental health literacy (MHL), which refers to the knowledge and beliefs related to helping people recognise, address and prevent mental illnesses [5], is an important component in the construction of a healthy China [6]. Previous studies have shown that patients with coronary artery disease generally have low MHL [7]-[9]. Moreover, given that most of the current studies have been based on total scores, analysis of individual heterogeneity has been lacking. Latent category analysis explains the associations between exogenous indicators through latent classes, thereby maintaining local independence and better explaining the nature of the problem from an individual perspective [10]. Therefore, to provide a reference for the implementation of precise interventions for MHL in patients with coronary artery disease, the current study used Latent Class Analysis (LCA) to categorise patients with coronary artery disease according to their MHL characteristics, explored factors influencing MHL and examined the relationship between the various MHL categories and quality of life.

The current study categorised the MHL of patients with coronary artery disease into four latent categories, namely low literacy (13.5%), high knowledge-low resources (25.5%), low knowledge-high resources (30.2%) and high literacy (30.8%). Notably, our findings showed that patients in the “low literacy” category were more likely to develop negative emotions and experience psychological difficulties, have difficulty coping with the psychological stress of the disease and have a twofold higher risk of complications than did those in the high literacy category [15]. Patients with low literacy may lack the necessary health knowledge and skills to effectively manage their health conditions and make full use of available health-care resources, suggesting that health knowledge and skills training provided by healthcare professionals through health education activities can help them better understand their disease and treatment options, improve self-management skills and enhance their personal coping abilities. Moreover, 25.5% of our patients were in the “high knowledge-low resources type”, who had considerable knowledge regarding coronary artery disease but lacked practical resources (financial support, social support etc.), which made it difficult for them to prevent, manage and control the disease. Healthcare professionals can therefore suggest relevant policies that provide appropriate resource support, such as financial assistance or access to exercise facilities, to help patients overcome practical difficulties, better implement self-management and strengthen their perceived control over their disease, thereby creating an effective virtuous circle [16]. Besides, 30.2% were in the “low knowledge-high resource type”. Although these patients lacked in-depth knowledge of coronary artery disease, they may have possessed sufficient financial and social support, which facilitates disease prevention and management. However, they may be unaware of how to fully utilise these resources to improve their health. Studies have suggested that healthcare professionals targeting such patients can provide health education to help them understand coronary artery disease and its management and better utilise available resources.

Evidence has shown an association between the level of MHL and age, such that the low literacy, high literacy and high knowledge-low resource groups are more likely to comprise middle age and young patients, old age patients and very old age patients, respectively. According to the actual situation in China, patients in their middle age, old age and very old age have been described as those aged 18 - 59, 60 - 79, and 80 years and older, respectively [17]. Young and middle-aged patients have low levels of MHL given their need to assume multiple social roles, high social and work pressures, lack of effective psychological adjustment, inability to promptly resolve negative emotions and insufficient attention to their own mental health [18]. Conversely, elderly patients are socially experienced and have the time and energy to acquire health information through diverse channels and methods, and therefore have a fuller knowledge of mental health [19]. Very old age patients are older and have a weakened ability and willingness to accumulate new knowledge, as well as a decreased ability to obtain mental health information from outside sources [17], which hinders access to mental health resources, thereby lowering their level of MHL. Therefore, other health management organisations should expand the channels of mental health education and enrich the content of mental health education. Moreover, healthcare professionals should develop appropriate mental health education programs according to the age and mental health needs of the patients and guide them in acquiring more comprehensive mental health knowledge to improve their MHL level.

Monthly income has been directly associated with the level of MHL, such that low-income patients were more likely to be included in the low-literacy group, consistent with the findings of Song [20] and Laoise [21]. Patients with belonging to lower-income families are more concerned about meeting basic needs, pay less attention to mental health knowledge, have fewer available resources and are prone to neglecting mental health problems [22]. In contrast, patients from higher- income families are more likely to seek resources to enhance their spiritual and cultural needs [20] and pay more attention to their own mental health after meeting their material needs. Therefore, healthcare professionals should have a comprehensive understanding of the basic needs of each patient, improve patient communication and interaction, identify the psychological problems of each patient as early as possible and provide guidance and help patients expand their mental health knowledge to correctly understand the disease. Simultaneously, we recommend that the relevant departments provide medical assistance, such as medical subsidies, to low-income families and appropriately increase the reimbursement rate.

The results of the current study showed that after controlling for confounders, low literacy, high knowledge-low resources and low knowledge-high resources positively predicted quality of life (P < 0.05). This finding indicates that an individual’s quality of life is affected by not only their level of knowledge and resources but also their level of MHL. Increasing the level of MHL can help improve mental health, reduce burden and enhance quality of life [23]. Previous studies have shown that certain psychological interventions, such as positive thinking therapy [24], mental resilience training [25] and focused solution short-course psychological intervention [26], can effectively improve patients’ quality of life. Therefore, we recommended that healthcare professionals emphasise the positive impact of MHL on quality of life and that factors such as individual literacy, knowledge and resources be comprehensively considered in the pursuit of better quality of life.

The current study has some limitations worth noting. First, this study was conducted in only one tertiary hospital and did not cover other hospital levels. Future studies may consider launching a large-scale study involving hospitals from different regions to obtain more comprehensive data. Second, our sample size was quite small. As such, future studies should include a larger sample size to improve data representativeness.

Improving MHL is important for the prevention and treatment of coronary artery disease. According to the results of our latent category analysis, the MHL of patients with coronary artery disease can be categorised into four types: low literacy, high knowledge-low resources, low knowledge-high resources and high literacy, highlighting the need for healthcare professionals to adopt different intervention and support strategies according to patient type. For different types of patients, appropriate health knowledge and skills training, practical resource support, disease awareness and resource utilisation ability assistance should be provided. This categorisation and management will help patients meet their needs and improve their MHL and quality of life.

Relevance for Clinical Practice

Mental health literacy in patients with CAD is crucial for improving psychological adaptability and quality of life. First, by detecting differences in mental health literacy traits, healthcare providers can gain a better understanding of their patients’ particular knowledge, beliefs, and resources. Second, the study discovered a correlation between mental health literacy and quality of life, emphasizing the necessity of psychological interventions in improving the well-being of patients. Consequently, healthcare practitioners can devise more individualized mental health intervention techniques to effectively improve the quality of life and psychological adaptability of patients with CAD.

The authors sincerely thank all participants and students who contributed to this study. Also, the authors would like to thank the Second Clinical Medical School of Zhengzhou University where the data were collected for their support.

Qiuju Shan and Panpan Wang were responsible for the formulation of the article framework; Jing Zhao, Zhenzhen Wang, Miaoliu Lian and Yikai Liu were responsible for the data collection and process; Panpan Wang and Yongxia Mei were responsible for the content supplement; Zhiguang Ping was responsible for the data analysis and improvement of the article. All authors read and approved the final manuscript.

This study was supported by the funding from Science and Technology Department of Henan Province in China (242102310067), Medical Science and Technology Tackling Program of Henan Province (LHGJ20210414, LHGJ20220514), and Science and Technology Department of Henan Province in China (232102311023).

The data are not publicly available due to privacy or ethical restrictions.

This study protocol was approved by the Second Clinical Medical School of Zhengzhou University (Date: 14.04.2021 & No: 2021281). All the patients included in the study were informed in advance of the study content and that they had the right to withdraw from the research at any time.

The authors declare no conflicts of interest regarding the publication of this paper.