Health behaviours as a mediator between health locus of control and cardiovascular risk in young adults with congenital heart defects

Young adults with adult congenital heart disease (ACHD) often present modifiable cardiovascular risk factors. We examined whether health behaviours mediate the associations between health locus of control (HLoC) and cardiovascular risk. In 201 young adults with ACHD (18-31 years), we assessed HLoC using the Multidimensional Health Locus of Control (MHLC) scale, health behaviours using the Health Behaviour Inventory (HBI), and cardiovascular risk using the exploratory ASCRF index. We estimated standardised indirect effects (β_indirect) with 95% confidence intervals using Monte Carlo simulations. The mean ASCRF score was 2.78 ± 1.32, and unhealthy dietary habits (76.62%) and overweight/obesity (50.25%) were common. Internal HLoC was associated with a lower ASCRF, whereas chance HLoC was associated with a higher ASCRF; powerful others HLoC showed no total association. HBI fully mediated the I-HLoC-ASCRF association (β_indirect = - 0.09; 95% CI - 0.12 to - 0.06) and partially mediated the C-HLoC-ASCRF association (β_indirect = 0.06; 95% CI 0.04 to 0.08). For P-HLoC, HBI showed inconsistent mediation (suppression; β_indirect = - 0.07; 95% CI - 0.09 to - 0.05). Subscale analyses indicated domain-specific mediating pathways involving dietary habits, preventive behaviours, and health practices, but not positive mental attitude. Health behaviours-particularly diet and routine preventive practices-may represent key pathways linking HLoC with cardiovascular risk in young adults with ACHD.