Synergistic Impact of Shift Work and Atherogenic Index of Plasma on Subclinical Atherosclerosis: A Cross-Sectional Study

Abstract Introduction To investigate the independent and combined effects of shift work and the Atherogenic Index of Plasma (AIP) on carotid intima-media thickness (cIMT), with the aim of determining whether a synergistic effect exists between these factors during the early stages of subclinical atherosclerosis. Methods A cross-sectional design was employed, involving 751 employed participants. Data were obtained via questionnaires and physical examinations. Participants were stratified into four groups according to shift work status and AIP level (using the 75th percentile(value: 0.25) as the cutoff): non-shift with low AIP (Group 1, reference group), shift with low AIP (Group 2), non-shift with high AIP (Group 3), and shift with high AIP (Group 4). One-way analysis of variance (ANOVA) was conducted to compare differences in cIMT across the groups, and multiple linear regression models—progressively adjusted for demographic, lifestyle, and clinical covariates—were utilized to evaluate the independent association between group membership and cIMT. An interaction term was introduced to assess the potential interaction between shift work and AIP. Results Significant differences in mean cIMT were observed among the four groups ( P< 0.001), demonstrating a clear gradation: Group 1 (0.58 ± 0.15 mm), Group 2 (0.68 ± 0.16 mm), Group 3 (0.71 ± 0.13 mm), and Group 4 (0.89 ± 0.17 mm). In the fully adjusted regression model, compared with the reference group, cIMT increased significantly by 0.11 mm (95% CI : 0.07–0.14) in Group 2, 0.13 mm (95% CI : 0.08–0.18) in Group 3, and 0.32 mm (95% CI : 0.28–0.36) in Group 4 (all P < 0.001). Moreover, the interaction analysis revealed a significant positive interaction between shift work and AIP on cIMT ( β = 0.106, 95% CI : 0.022–0.191, P = 0.014). Conclusion Both shift work and elevated AIP are independently associated with increased cIMT, and their coexistence is associated with a synergistic increase in the burden of subclinical atherosclerosis.These findings suggest that occupational health management should integrate assessments of work schedules and lipid metabolism indicators (AIP) to implement targeted interventions for individuals at dual high risk due to shift work and high AIP.