Epilepsy, a chronic brain disorder characterized by abnormal neuronal discharges, poses a common neurological challenge in children. Though its onset is often subtle, neonatal seizures related to epilepsy can be detrimental to the developing brain (Pack, 2019). According to epidemiological data, the incidence of epilepsy in children ranges from 33.3 to 82 cases per 100000 individuals annually (Fine and Wirrell, 2020), which is higher than that in adults. This condition can inflict significant neurological harm in children, leading to obstacles in independent learning, delayed brain development, intellectual impairment, and substantial impacts on growth, development, and psychological wellbeing (Beghi, 2020; Choi et al., 2022). Currently, epilepsy has been recognized as a priority for prevention and treatment among neurological and mental diseases by the World Health Organization.

Valproic acid (VPA) serves as a primary antiepileptic medication utilized in pediatric clinical use, exhibiting therapeutic efficacy across various types of seizures (Pong et al., 2023). Nevertheless, therapeutic index of VPA is narrow, and it can provoke a range of adverse reactions. It is recommended that the effective and safe treatment concentration range is 50–100 mg/L by the guidelines (Hiemke et al., 2018). VPA has high binding affinity to plasma protein, and the free fraction responsible for its pharmacological and toxic effects accounts for 5%–10% of the total drug. In order to reduce the risk of adverse effects and drug interactions, patients need therapeutic drug monitoring (TDM) to assess VPA levels especially for the children who usually has relatively lower plasma protein levels than adults (Charlier et al., 2021). Existing studies have established that VPA undergoes primary metabolism by hepatic enzymes in the liver and is subsequently eliminated through renal excretion after conjugation with glucuronic acid (Chatzistefanidis et al., 2012). However, due to the incomplete maturation of the hepatic enzyme system in children compared to adults, long-term use of VPA can negatively impact liver function. Additionally, dyslipidemia and significant weight gain are adverse effects associated with VPA that warrant attention. Lipids play diverse roles in cellular function, and abnormal plasma lipoprotein levels have been linked to the progression of certain diseases, such as atherosclerotic vascular disease (Abd Alamir et al., 2018) and nonalcoholic fatty liver disease (NAFLD) (Katsiki et al., 2016).

VPA, acting as a branched-chain short-chain fatty acid analogue, has been implicated in promoting fat storage, consequently contributing to weight gain. This effect occurs through mechanisms such as the reduction of leptin levels, decreased insulin sensitivity, and impairment of fatty acid β-oxidation. Indeed, VPA has been shown to elevate the level of leptin and exert dual actions. These actions involve modulation of the central nervous system to regulate appetite and energy expenditure, while simultaneously influencing the peripheral regulatory system to enhance insulin sensitivity and promote fatty acid oxidation, thereby reducing levels of circulating peripheral fatty acids. These effects contributed to the development of dyslipidemia and significant weight gain (Belcastro et al., 2013; Li et al., 2019). Dyslipidemia significantly heightens the risk of cardiovascular disease, and studies have suggested dyslipidemia in childhood is associated with an increased likelihood of cardiovascular events in adulthood. During childhood, atherosclerotic cardiovascular diseases are viewed as preclinical conditions, where dyslipidemia plays a crucial role. Fortunately, due to its impact on cardiovascular structure, dyslipidemia may be reversible during childhood. However, without proactive management, the condition may progress, ultimately leading to coronary heart disease, a primary cause of adult mortality (Arts et al., 2014; Pires et al., 2016; Yeung et al., 2021). According to data from the Chinese National Cardiovascular Center in 2010, cardiovascular diseases accounted for 40.4% of all deaths in China, making them the leading cause of mortality (Pan et al., 2016). Therefore, it is imperative to identify and manage dyslipidemia in children.

Currently, available studies on VPA-induced dyslipidemia (VID) in pediatric patients with epilepsy primarily concentrate on alterations in the lipid metabolism profile (Guo et al., 2022), potential mechanisms (Belcastro et al., 2013), and individual influencing factors (Attilakos et al., 2006). Long-term observational clinical studies reveal that VID is influenced not only by the drug properties but also by various physiological factors and individual differences. Identifying high-risk factors for VID in pediatric patients with epilepsy is beneficial for effective prevention strategies. Risk prediction models serve as valuable tools for this purpose (Wallisch et al., 2021; Canney et al., 2022). However, it is worth noting that there have been no reports of risk prediction models for dyslipidemia in patients on long-term VPA use, especially in pediatric patients, where both risk factors and models have not been documented.

Although VPA may induce dyslipidemia, the underlying factors contributing to this abnormality in children remain inadequately explored. This highlights the potential value of investigating VID within this specific pediatric cohort. Therefore, our retrospective cohort study was conducted to investigate the relationship between VID in pediatric patients and various physiological factors, medication history, and baseline biochemical indicators. Binary logistic regression was used to establish a dyslipidemia prediction model and identify independent risk factors. The primary objective of this study is to anticipate the likelihood of future dyslipidemia events in pediatric patients by monitoring their risk factors for emerging metabolic disorders. Furthermore, it aims to provide a more scientifically tailored approach to the clinical use of VPA, offering individualized medication recommendations and improving the precision of VPA treatment in children.

Currently, there exists a notable research gap regarding the identification of risk factors for dyslipidemia in pediatric epilepsy patients undergoing VPA treatment. In this study, we conducted a retrospective analysis of the lipid profiles of 157 pediatric epilepsy patients undergoing VPA treatment to discern independent risk factors for dyslipidemia in this specific group of children. We confirmed that: (1) DBIL, Duration of medication, and ALB emerged as independent protective predictors against dyslipidemia induced by VPA in pediatric epilepsy patients, while BMI and AST were risk factors; (2) among the individual risk factors, DBIL had a stronger predictive ability compared to other factors when predicting individually; and (3) the combination of these five risk factors exhibited the strongest predictive capability compared to individual risk factors.

Our study underscores the significance of DBIL levels prior to VPA treatment as a prominent predictor of VID in pediatric patients with epilepsy. Compared with other single predictors, DBIL demonstrated the strongest predictive power, with an area under the ROC curve of 0.690 (95%CI: 0.607–0.772, p < 0.0001). Therefore, within the normal range, high DBIL was a protective factor for blood lipids in children with epilepsy treated with VPA. This was confirmed by the correlation between DBIL and blood lipid indexes. Bilirubin, a product of heme metabolism, arises from the breakdown of iron porphyrin compounds within aging red blood cells. This process yields two main forms of bilirubin: conjugated bilirubin (DBIL) and unconjugated bilirubin (indirect bilirubin). It serves a clinical diagnosis of hemolysis, neovascularization and hepatobiliary diseases (Fevery, 2008). VPA undergoes intricate metabolic transformations primarily in the liver. Notably, its reactive metabolites have been reported to be associated with hepatotoxicity (Guo et al., 2019). Abnormal elevation of bilirubin is one manifestation of impaired liver function. In an individualized treatment model for patients with bipolar disorder receiving VPA, researchers observed that indirect bilirubin was positively correlated with VPA daily dose (Zheng et al., 2022). Interestingly, it is indicated that bilirubin possesses potent antioxidant properties, which include anti-inflammatory, antioxidant, and free radical scavenging properties (Stocker et al., 1987). The elevation of bilirubin facilitates the breakdown and metabolism of low-density lipoprotein cholesterol, leading to a reduction in its concentration in the body and consequently exerting an anti-atherosclerotic effect (Vogel et al., 2017). Therefore, a decrease in serum bilirubin concentration weakens its antioxidant efficacy, potentially resulting in abnormal lipid metabolism. Furthermore, animal experiments have demonstrated that bilirubin can regulate genes involved in lipid metabolism by activating peroxisome proliferator-activated receptor alpha (PPAR-α), thus contributing to lipid regulation (Stec et al., 2016). A cross-sectional and longitudinal study conducted by Eiji Oda, involving a health screening population, aimed to explore the relationship between serum bilirubin levels and dyslipidemia. The study revealed a significant correlation, indicating a decrease in total bilirubin levels was notably associated with hypertriglyceridemia, low HDL and hypercholesterolemia (Oda, 2015). This was consistent with the findings of our study. Dyslipidemia serves as a crucial indicator of metabolic syndrome (MS). The relationship between different bilirubin parameters and MS was evaluated in a Korean study, which found that direct bilirubin, indirect bilirubin, and total bilirubin levels were negatively correlated with MS, but DBIL was more closely related to MS (Jo et al., 2011). Therefore, within the normal range, DBIL was a protective factor for VID in children with epilepsy.

Interestingly, our study also revealed that pediatric epilepsy patients undergoing VPA treatment for more than 3 months exhibited a protective effect against VID compared to those with a medication duration of less than 3 months. A study by Kusumastuti K, employing logistic regression, made a similar discovery. Specifically, it was found that the risk of developing high total cholesterol levels in adult patients with VPA use for more than 12 months was 3.68 times lower than that with VPA use for less than 12 months (Kusumastuti and Jaeri, 2020). In a meta-analysis conducted in 2022, researchers observed that long-term VPA treatment had the potential to reduce total cholesterol and low-density lipoprotein cholesterol levels. This effect may be achieved by enhancing certain organs/cell organelles that contribute to improving cholesterol metabolism (Guo et al., 2022). Huang et al. demonstrated that VPA exhibits the capability to mitigate oxidative stress in the endoplasmic reticulum via the pathway of glycogen synthase kinase 3/β which contributes to cholesterol metabolism and the pathogenesis of atherosclerosis (Huang et al., 2017). On the other hand, the main pathway of VPA bioconversion involves glucuronidation, and glucuronidase may be inhibited by VPA or its metabolites, resulting in decreased synthesis of TC, LDL-C and HDL-C. On the contrary, children with VPA have been reported to develop hyperinsulinemia, which can stimulate lipogenesis, resulting in the accumulation of triglycerides and hypercholesterolemia (Kanemura et al., 2012; Belcastro et al., 2013). This suggests that the mechanism of action and metabolic effects of VPA in vivo are very complex. VPA may exert bidirectional effects on lipid metabolism through different mechanisms. In the early stage of VPA treatment, the insulin level responds rapidly, leading to an abnormal trend of blood lipid elevation. However, with the long-term use of VPA, VPA acts on other pathways to reduce blood lipid levels. Similar trends were observed in both adults and children. However, due to the immature development of liver and other metabolic tissues in children, there were differences in the time points of the bidirectional regulation of blood lipids by VPA. Weight gain is recognized as one of the most overt features of dyslipidemia, and according to the literature, weight gain during VPA treatment can be observed within the first 3 months of treatment (Verrotti et al., 2011; Sidhu et al., 2017). Furthermore, another study indicated that VPA administration reduced blood glucose levels and increased motivation to eat, potentially leading to increased energy intake, particularly in the early stages of treatment (Martin et al., 2009). At the same time, due to the immature but fast development of liver and other organs in children, they may respond more rapidly and severely to drug effects. Therefore, we categorized treatment duration as more or less than 3 months, and found that close attention should be paid to blood lipid indexes in children with epilepsy treated with VPA in the early stage.

Baseline ALB was also identified as a protective predictor of VID in children with epilepsy. ALB is the predominant protein in human plasma and represents the most abundant circulating protein in the extracellular compartment, which plays a critical role in the distribution of body fluids (Caraceni et al., 2013). Its strong binding and transport functions enable it to serve as a ligand for various drugs, thereby influencing the pharmacokinetics of numerous medications. Additionally, ALB engages in binding with bilirubin, free fatty acids, minerals, and hormones, participating in multiple metabolic reactions (Levitt and Levitt, 2016; Chen et al., 2021). Studies have been shown that a deficiency in ALB disrupts intravascular lipolysis, resulting in a shortage of free fatty acids and a diminished clearance of triglyceride, consequently leading to hypertriglyceridemia (Figueira et al., 2010). Interestingly, research has demonstrated that ALB infusion helps alleviate dyslipidemia in models of anaplastic anemia, providing compelling evidence for the positive role of serum albumin in regulating lipoprotein metabolism (Rosipal et al., 2006; Del Ben et al., 2013; Crook, 2016). All of these observations align with the findings of our study, indicating that ALB serves as a protective predictor of dyslipidemia in children with epilepsy. Elevated levels of ALB before the administration of VPA are beneficial for the protection of lipids and reduction of dyslipidemic events in children with epilepsy.

BMI and AST before VPA treatment were considered independent risk predictors of VID in pediatric patients with epilepsy after accounting for the effects of other factors. BMI is a reliable indicator of obesity, which is an important symptom of dyslipidemia, as supported by numerous studies (Zaid et al., 2017; Yu et al., 2022). Notably, one of the adverse effects of VPA is the potential increase in BMI and the risk of obesity in patients. Consequently, baseline BMI before VPA treatment serves as a crucial risk predictor for dyslipidemia in pediatric patients with epilepsy. Given the pivotal role of the liver in regulating lipid metabolism, it is evident that liver injury can significantly impact lipid metabolism. ALT and AST represent the two most common aminotransferase markers used clinically to assess liver injury or the severity of liver disease. The effect of VPA administration on the elevation of liver enzymes is evident, especially in young children with immature liver function. Oxidative stress in the mitochondria due to VPA usage can further exacerbate liver damage. Hence, it is imperative to regularly monitor liver function in patients with VPA, especially in pediatric patients, both prior to treatment and during its course, to prevent the risk of liver injury as well as lipid metabolism disorders.

We also explored VPA C_trough in vivo as an independent risk factor for VID in children with epilepsy. Notably, previous studies examining the risk factors for hyperammonemia induced by VPA revealed that the VPA C_trough and the standard daily dose of VPA could significantly predict the blood ammonia levels (Duman et al., 2019). Unfortunately, in this study, the VPA C_trough and the standard daily dose of VPA did not emerge as predictors of dyslipidemia in binary logistic regression. Further analysis was conducted to examine the relationships between standard daily dose of VPA, VPA C_trough and the four lipid parameters (TC, TG, HDL-C and LDL-C) in the whole patient cohort. However, no significant correlations were found (Supplementary Table S2). Specifically, in the dyslipidemia group, the associations between lipid parameters (TC, TG, HDL-C and LDL-C) and the standard daily dose of VPA, VPA C_trough were also investigated, and no results approached significance either (Supplementary Table S3). These findings suggested that VID in epileptic children in this study was no related to VPA C_trough or standard daily dose.

There were several limitations in this study. First, this study was carried out in a single center, and the study population primarily comprised children, resulting in a relatively small sample size. Therefore, the prediction model could not yet be extrapolated to other centers. To enhance the generalizability of findings, it is essential to conduct multi-center collaborative research to further expand the sample size. Second, it was a retrospective study, although various significant factors have been analyzed, there remains the possibility of uncontrollable interfering factors. Moreover, there could exist unknown or unmeasured risk factors that were not accounted for in this analysis. Subsequent prospective studies can be designed to incorporate more possible risk factors. Additionally, such studies could implement controls for changes during follow-up and undertake further systematic evaluations. Finally, due to the limited prevalence of genetic testing in clinical practice, we were unable to collect information about the patients themselves regarding the genotypic polymorphisms that were specific influences on VPA metabolism. It is found that the genotype polymorphisms of patients, such as CYP2C9 and CYP2A6, were important factors for dyslipidemia (Yoon et al., 2020). At the same time, pharmacogenetics is helpful to understand the treatment efficacy and adverse effects. It has been reported that the polymorphism of the SCN1A gene may play a role in the response to anti-epileptic drugs in patients with drug-resistant epilepsy, which is of great significance for clinical practice (Margari et al., 2018). Therefore, it is necessary to conduct prospective studies by combining multiple centers, expanding the sample size, and expanding important potential risk factors.

This study has identified DBIL, Duration of medication, ALB, BMI, and AST as independent risk factors for VID in pediatric epilepsy patients. By combining these five risk factors into a composite predictive factor, we can predict 77.7% of blood lipid abnormal events, demonstrating a strong predictive capability. This finding is highly significant for pediatric epilepsy patients undergoing VPA treatment. Also, these factors can guide precise VPA dosing, maximizing the therapeutic effects of VPA while minimizing the risk of blood lipid abnormalities. This approach also aims to reduce the risk of future cardiovascular events in children. Ultimately, it provides a more scientifically tailored approach to the clinical use of VPA, enhancing its precision in pediatric patients.