AHA Scientific Sessions 2026 Abstract · Nov 2, 2026
Long-Term Trends in C-reactive Protein and Interleukin-6 Levels in the Danish Population: A Population-Based Study of Cardiovascular Inflammation
By Hansen S, Flege MM, Husemoen LL et al.
Introduction: Cardiovascular (CV) inflammation is a key contributor to CV disease, yet its distribution and temporal trends in the general population remain insufficiently characterized. C-reactive protein (CRP) and interleukin-6 (IL-6) are established biomarkers of CV inflammation. We aimed to describe levels of CRP and IL-6 across several decades in the general Danish population. Methods: We conducted a population-based observational study using data from three independent Danish health examination surveys conducted in 1988, 2000, and 2014, based on cohorts of randomly invited inhabitants of western Copenhagen. Blood samples were collected from all participants and stored at –80°C. IL-6 was measured in 2025, and CRP was measured close to sample collection for the surveys in 1988 and 2000, and in 2025 for the 2014 survey. Analyses were restricted to individuals aged 35-61 years, corresponding to the widest age range represented across all three surveys. Log ₂ -transformed CRP and IL-6 values were modeled using restricted cubic splines with age treated as a continuous variable. Predicted values were back-transformed to obtain age-specific geometric mean biomarker level. These estimates were then standardized to the age distribution of the Danish population in the corresponding survey years (1988, 2000, and 2014) and stratified by sex. In addition, the age-standardized proportion of individuals with CRP ≥ 2 mg/L was estimated. Finally, biomarker levels from the 2014 survey were standardized to the age distribution of the Danish population in 2024. Results: We included a total of 12,140 participants from the three surveys. Baseline characteristics are shown in Figure 1. CV inflammation increased over time, with geometric mean CRP levels (mg/L) rising from 1.1 (95% CI 1.0-1.2) in both sexes in 1988 to 1.5 (1.4-1.6) in men and 1.7 (1.6-1.8) in women in 2014 (Figure 2). Corresponding IL-6 levels (pg/mL) increased from 1.0 (0.9-1.1) in men and 0.9 (0.8-0.9) in women in 1988 to 1.8 (1.8-1.9) in both men and women in 2014 (Figure 2). Standardization to the 2024 Danish population age distribution yielded estimated contemporary CRP levels of 1.5 mg/L (1.4-1.6) in men and 1.7 mg/L (1.6-1.8) in women, while corresponding IL-6 levels were 1.8 pg/mL (1.8-1.9) in both sexes (‘Denmark 2024’ in Figure 2). The proportion of individuals with CRP ≥ 2 mg/L rose from 29% (26-33%) in 1988 to 32% (30-34%) in 2014 in men and from 30% (26-34%) in 1988 to 39% (37-41%) in 2014 in women, with estimated contemporary proportions of 33% (31-35%) in men and 39% (37-41%) in women (Figure 3). Conclusion: Our results indicate that CV inflammation in the Danish general population has increased over the past decades. The factors underlying this increase warrant further investigation. These findings may provide important insight into long-term population trends in inflammation and may help inform future strategies for CV disease prevention.