Socioeconomic inequalities in paediatric metabolic syndrome: mediation by parental health literacy

**Background:** Socioeconomic inequalities exist in paediatric metabolic syndrome (MetS), a cluster of cardiometabolic risk factors that predicts long-term cardiovascular risk. Parental health literacy—the capacity to obtain, process, and understand health information—may be a modifiable mechanism linking parental socioeconomic status (SES) to children's MetS, but this pathway is understudied. This study aimed to assess the extent to which parental health literacy mediates the relationships between different measures of parental SES and paediatric MetS.

**Methods:** Data were drawn from the prospective, multigenerational Lifelines Cohort Study in the Netherlands. The analytic sample included 6,683 children aged 8–17 years at the fourth assessment wave (T4) who had linked parental data and a mean follow-up of 36.2 months (SD 9.3). Children under 8 or over 17 at T4 were excluded because MetS components were not assessed or because the study focused on paediatric MetS. SES was measured using three separate indicators at baseline (T1): parental education (recoded into years of education), equivalized household income, and occupational prestige (Treiman's Standard International Occupational Prestige Scale). Parental health literacy was measured at T3 using three validated questions from Chew et al., dichotomized into low (score 3–12) and adequate (13–15). The primary health literacy variable used maternal data, with paternal data used if maternal data were missing. MetS was operationalized as a continuous MetS (cMetS) score at T4, calculated by summing age- and sex-standardized residuals of waist circumference, mean arterial pressure, fasting glucose, triglycerides, and reversed HDL. Causal mediation analysis using natural effects models (medflex package in R) was conducted, with multiple imputation (predictive mean matching, 20 imputations) for missing data. Sensitivity analyses used average parental health literacy (both parents' scores).

**Key Results:** One-fifth (20.0%) of children lived in households with low parental health literacy. Higher parental SES was associated with lower cMetS scores. An additional 4 years of parental education (e.g., university vs. secondary school) was associated with cMetS scores 0.499 units lower (95% CI: 0.364–0.635; Cohen's d = 0.18, a small effect). A 1 SD increase in parental income was associated with 0.136 units lower cMetS (95% CI: 0.052–0.219; d = 0.05), and a 1 SD increase in occupational level with 0.196 units lower cMetS (95% CI: 0.108–0.284; d = 0.07). Parental health literacy partially mediated these pathways: the proportion mediated was 6.7% for education (indirect effect: −0.033, 95% CI: −0.065 to −0.001), 11.8% for income (indirect effect: −0.016, 95% CI: −0.028 to −0.004), and 8.3% for occupation (indirect effect: −0.016, 95% CI: −0.029 to −0.004). In sensitivity analyses using average parental health literacy, the proportion mediated increased to 10.5% (education), 17.5% (income), and 12.5% (occupation), though the pattern of findings remained consistent.

**Clinical Implications:** Socioeconomic inequalities in paediatric MetS are relatively small, with the largest effect observed for parental education. Parental health literacy explains a modest portion of these inequalities, suggesting that interventions targeting parental health literacy may have a limited but meaningful impact on reducing socioeconomic disparities in children's cardiometabolic health. The finding that the proportion mediated was largest for income (11.8%) suggests health literacy may be particularly relevant for lower-income families, potentially by enabling better lifestyle choices given constrained resources. The increased mediation when using average parental health literacy implies that one parent's adequate literacy may compensate for the other's low literacy. The authors note that children lost to follow-up had slightly worse biomarkers and lower SES, which may have introduced minor bias. The health literacy measure focused on functional health literacy, and more comprehensive measures (including critical and communicative health literacy) might show stronger mediating effects. Further research is needed on the role of paternal health literacy and on health literacy interventions targeting both parents and children.