Hyperlipidemia is a disease characterized by the decrease of serum cholesterol, triglyceride and low-density lipoprotein and the increase of high-density lipoprotein, which is one of the factors inducing atherosclerotic cardiovascular and cerebrovascular diseases [1] . With recent lifestyle changes, the incidence of hyperlipidemia—usually a geriatric disease—in the younger population is increasing, endangering public health [2] . At present, the treatment of hyperlipidemia is mainly based on statins and fibrates, combined with diet and exercise intervention [3] . However, existing treatments had limited effects on improving hyperlipidemia symptoms and controlling its complications [4] .

Traditional Chinese Medicine (TCM) syndrome is the understanding of the etiology and pathological mechanism of a disease at some stage, reflecting the innate character of the disease and acting as the basis of its clinical treatment [5] . In recent years, TCM, characterized by syndrome differentiation and treatment, plays an increasingly important role in the treatment of hyperlipidemia and its complications [6] . Identifying the different syndrome types of the disease could help doctors identify the main causes and progression of the disease at the current stage, so as to better guide clinical treatment. Therefore, exploring the distribution of the main clinical TCM syndromes and the main cause of hyperlipidemia has a positive effect on the understanding and treatment of the disease. Unfortunately, the present research is deficient in the exploration of diagnosis, differentiation, and classification of the clinical symptoms of hyperlipidemia, which poses limitations on the clinical diagnosis and treatment of the disease. Consequently, investigating the distribution of major clinical TCM syndromes and the primary etiology of hyperlipidemia has become a focal point of current research.

In this study, we analyzed clinical data obtained in an epidemiological survey of 1012 hyperlipidemia patients, explored the distribution pattern of TCM syndromes of hyperlipidemia, and analyzed relevant factors. Therefore, we provide a valuable reference for the standardization of hyperlipidemia syndrome differentiation to effectively direct clinical practice.

Hyperlipidemia, a prevalent metabolic disorder, stands as a pivotal contributor to the development of atherosclerotic cardiovascular and cerebrovascular diseases [9] . It has emerged as a significant public health concern, posing a substantial threat to societal well-being and incurring a heavy economic burden globally [10] . In recent years, Traditional Chinese Medicine (TCM) has demonstrated considerable potential as a therapeutic modality for hyperlipidemia, thereby emerging as a vital clinical intervention strategy in managing this metabolic disorder [11] . For instance, rigorous clinical trials have evidenced that the traditional Chinese medicine compound known as Shanhuang Jiangzhi Tablet effectively diminishes the serum levels of triglycerides, TC, and LDL-C among patients, offering a low-risk therapeutic approach for blood lipid reduction [12] . However, the underlying principle of Traditional Chinese Medicine (TCM) in treating hyperlipidemia is rooted in TCM theory, particularly the establishment of syndrome classification specific to the disease. Consequently, elucidating the distinct characteristics of TCM syndrome classification pertaining to hyperlipidemia holds a pivotal role in directing and optimizing TCM therapeutic interventions for this metabolic disorder.

In the present investigation, we initially conducted an analysis of the age-specific distribution patterns observed within a cohort of 1012 hyperlipidemia cases. Our findings revealed that individuals aged 50 years and above constituted a substantial proportion (73.52%) of the hyperlipidemia patient population, whereas those under 40 years of age comprised merely 11.36% of the total. This distribution underscores the prevalence of hyperlipidemia among middle-aged and elderly individuals, corroborating previous literature [13] . Nevertheless, it is noteworthy that amidst shifts in lifestyle habits and escalating societal pressures, there is a discernible trend towards an escalating incidence of hyperlipidemia among young and middle-aged adults. Consequently, this underscores the paramount importance of early intervention strategies for hyperlipidemia, warranting heightened attention and proactive measures. Furthermore, we conducted an analysis to investigate the gender-specific characteristics of hyperlipidemia. Our findings indicate that the incidence of hyperlipidemia does not exhibit significant gender disparities, underscoring its status as a prevalent metabolic disorder that affects both males and females alike. Contrary to a prior study that proposed a gender-specific prevalence in familial hypercholesterolemia, reporting a higher proportion among women, our current investigation did not uncover significant sex-related characteristics [14] . This discrepancy may potentially stem from the presence of methodological biases or differing demographic and clinical characteristics between the study populations. Furthermore, we concentrated our efforts on elucidating the fundamental syndrome patterns of hyperlipidemia, aiming to provide clinical guidance and insights for therapeutic interventions. Our analysis, encompassing 1012 patients, revealed that the most prevalent Traditional Chinese Medicine (TCM) syndrome was qi-deficiency and blood stasis (23.52%), followed by liver depression and spleen deficiency (9.88%), qi stagnation and blood stasis (9.29%), phlegm stasis syndrome (7.41%), and syndrome of yang deficiency of spleen and kidney (6.92%). Notably, the syndromes of qi-deficiency and blood stasis and liver depression and spleen deficiency, both representing subtypes of qi-deficiency, collectively accounted for 33.4% (338 cases) of the total patient population. These findings underscore the pivotal role of qi-deficiency as a crucial pathological foundation in hyperlipidemia, suggesting that reinforcing and regulating qi may serve as a fundamental therapeutic principle in the management of this metabolic disorder. Crataegus pinnatifida (CP), a time-honored constituent of traditional Chinese medicine, is renowned for its capacity to harmonize qi flow and facilitate digestion [15] . Additionally, it serves as a functional food that embodies properties conducive to enhancing metabolic well-being. A prior investigation has elucidated the efficacy of CP in ameliorating metabolic disruptions elicited by high-fat diets, specifically addressing impairments such as glucose intolerance, insulin resistance, hyperlipidemia, and hepatic steatosis. This underscores the promising therapeutic potential of qi-regulating herbal remedies in the management of hyperlipidemia [16] . Furthermore, we conducted a thorough analysis of the gender-specific characteristics pertaining to Traditional Chinese Medicine (TCM) syndrome classifications of hyperlipidemia. Our findings revealed a notable preponderance of female patients (133 cases) over male patients (105 cases) among the 238 individuals diagnosed with qi-deficiency and blood stasis syndrome. Similarly, in the cohort of 100 patients suffering from liver depression and spleen deficiency, there was a distinct gender disparity, with 62 females and 38 males. These observations imply that women may be more susceptible to the manifestation of hyperlipidemia-related pathological alterations, potentially mediated by their heightened response to social pressures or lifestyle disruptions, which in turn could disrupt the harmonious flow of qi, a fundamental concept in TCM. This underscores the need for gender-sensitive approaches to understanding and managing hyperlipidemia.

In addition, our study also analyzed the common symptoms of hyperlipidemia. Our results suggest that the ten most common symptoms were dry eyes, dry mouth and throat (60.47%), tiredness and weakness (53.56%), forgetful (49.41%), excessive abdominal fat (45.35%), feeling painful (42.79%), fear of cold (40.81%), bitter taste (40.52%), sweating easily (37.65%), facial flushing (35.97%), dry skin (35.87%). Intriguingly, this observation deviates from the canonical clinical presentations of hyperlipidemia [17] , suggesting that in the clinical application of Traditional Chinese Medicine for managing hyperlipidemia, the categorization of syndrome types is grounded primarily in symptomatic manifestations, rather than the pathological biomarkers specific to hyperlipidemia. Besides, the limitation of this study is its reliance primarily on retrospective data, without delving into the biological diagnostic markers of syndromes. Future research could involve collecting clinical serum and plasma samples for molecular biological analysis to screen and identify relevant biomarkers for the diagnosis of disease syndromes.

In the TCM syndrome distribution in patients with hyperlipidemia, qi-deficiency and blood stasis syndrome and liver depression and spleen deficiency are the most common TCM syndromes in patients with hyperlipidemia. Furthermore, there exist gender disparities in the distribution of hyperlipidemia syndromes, with a preponderance observed among female patients. In the clinical management of hyperlipidemia, the utilization of TCM that embodies the therapeutic principles of “supplementing qi” and “regulating qi to alleviate depression” has gained increasing prominence, indicating that the latter principle could potentially emerge as a cornerstone in the clinical treatment of hyperlipidemia.

This work was supported by the National Natural Science Foundation of China (No. 82074331).