Comparison of interleukin-6 and high-sensitivity C-reactive protein for cardiovascular risk assessment: Findings from the MESA study

Background and aims Inflammation is a risk factor for major adverse cardiovascular events (MACE). Elevated levels of both high-sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL6) have been associated with MACE. However, few studies have compared IL6 to hsCRP for cardiovascular risk assessment. Using the MESA (Multi-Ethnic Study of Atherosclerosis) study cohort, we aim to compare IL6 to hsCRP. Methods We divided IL6 and hsCRP by their median values and created 4 groups i.e., low-low, high-low, low-high and high-high. The median follow-up was 14 years. Results 6614 (97 %) participants had complete baseline IL6 and hsCRP data. The correlation between hsCRP and IL6 was modest (Rho = 0.53). An IL6 ≥1.2 pg/mL (median) was present in 3309 participants, and a hsCRP ≥1.9 mg/L (median) was present in 3339 participants. Compared to participants with low IL6 and low hsCRP, those with high IL6 and high hsCRP were older (64 vs. 60 years), more frequently women (63 % vs. 45 %), and with more cardiovascular co-morbidities. hsCRP outcome associations lost statistical significance when adjusting for IL6: MACE HR (95%CI) 1.06 (0.93–1.20), p =0.39, whereas IL6 associations remained significant after adjusting for hsCRP: HR (95%CI) 1.44 (1.25–1.64), p <0.001. The C-index of Framingham score for was not improved by hsCRP but improved with IL6. Compared to participants with low IL6 and low hsCRP, those with high IL6, regardless of hsCRP, experienced an increased risk of MACE, heart failure and mortality. Conclusions In a diverse and asymptomatic population, IL6 showed a stronger association with atherosclerotic, heart failure and fatal outcomes than hsCRP.