Tracking total cholesterol across time: an age-period-cohort analysis of austrian blood donors from 1995-2024

Background Cardiovascular diseases (CVDs) cause the greatest disease burden worldwide, with high concentrations of total serum cholesterol (TC) being a major risk factor. To prevent CVDs effectively, understanding the sex-specific trajectories of TC progression in healthy individuals across different age groups and birth cohorts is essential. Since 1995, Tyrolean blood donors receive routinely measured TC levels after every blood donation. However, a differentiated long-term analysis is still lacking. Purpose The aim of this study was to analyse temporal trends in TC levels of blood donors (18-70 years of age) to provide a foundation for developing and/or refining prevention policies exemplified for the Austrian federal state Tyrol. Methods The study followed a retrospective observational design, including all blood donations registered between January 1995 and December 2024. An Age-Period-Cohort analysis was implemented to detect temporal trends in TC via generalised additive mixed models for both female (TCF) and male donors (TCM). Results We analysed data on 1,278,768 whole blood donations from 210,335 donors. TC levels fluctuated over time, showing an overall decline between 1995 (mean TCF: 228.0 mg/dL; mean TCM: 230.9 mg/dL) and 2024 (mean TCF: 208.8 mg/dL; mean TCM: 207.8 mg/dL) with the lowest mean TC levels in 2000 (mean TCF: 202.6 mg/dL; mean TCM: 205.2 mg/dL) and in 2010 (mean TCF: 202.7 mg/dL; mean TCM: 198.4 mg/dL). TC trajectories according to age showed distinct patterns between sexes. Female donors presented a delayed increase, reaching mean TC values above 200 mg/dL at the age of 35, yet starting at higher mean TC levels at the age of 18 (184.6 mg/dL) compared to male donors (153.2 mg/dL), who reach mean TC levels above 200 mg/dL at the age of 31. Generational trends showed an improvement of TC levels in higher age groups (birth years ~1955-1960), especially in male donors. Conclusion Despite detecting an overall improvement, TC levels rose above recommended thresholds already in the third decade of life. This highlights the need for early and low-level public health measures starting preferably in early adulthood in order to prevent future CVD.