Seasonal changes in lipid profiles and homocysteine in patients with and without coronary heart disease: a real-world paired retrospective study in a cold-climate region.

Background: Seasonal variation in cardiovascular events is well recognized in cold-climate regions. However, whether lipid profiles and homocysteine exhibit consistent seasonal patterns, and whether these patterns differ between individuals with and without coronary heart disease (CHD), remains incompletely characterized in real-world clinical settings. Methods: We conducted a retrospective, paired study including patients who underwent first-time measurements of lipid profiles and homocysteine in both summer (June-August) and winter (December-February) at a single center over a three-year period. Participants were stratified by CHD status. Within-individual seasonal differences were assessed using paired statistical tests. Seasonal changes were quantified as Δ (Winter - Summer), and between-group differences in Δ were compared. Effect sizes and complementary visualizations were used to characterize the magnitude and heterogeneity of seasonal responses. Results: Seasonal differences in lipid parameters and homocysteine were detectable but modest. Individuals without CHD showed greater seasonal responsiveness, with winter increases in LDL-C and reductions in total cholesterol, triglycerides, and homocysteine. In contrast, CHD patients exhibited attenuated seasonal variation, with a mild winter increase in LDL-C and a tendency toward lower HDL-C. Between-group comparisons of Δ revealed significant heterogeneity for triglycerides ( Conclusions: Seasonal variation in lipid profiles and homocysteine is modest but heterogeneous. Non-CHD individuals show greater seasonal sensitivity, whereas CHD patients exhibit blunted or directionally altered responses. These findings highlight the importance of incorporating seasonal context into lipid interpretation and individualized cardiovascular risk management in cold-climate regions.