Elevated High Sensitivity C Reactive Protein and Risk of Abdominal Aortic Aneurysm: A Prospective Population Based...

Inflammation seems to be crucial in the pathogenesis of abdominal aortic aneurysm (AAA). Previous research links inflammatory biomarkers, such as high sensitivity C reactive protein (hs-CRP), to AAA. Few studies, however, have used a prospective design. The aim of this study was to examine whether individuals with elevated hs-CRP have increased risk of AAA, using a prospective and population based design.

This prospective, population based, cohort study included 46 322 participants in the Trøndelag Health Study (HUNT) in Norway (53.7% female). During a median follow up of 12.6 years (range 0 - 26 years), 407 individuals were diagnosed with AAA (22.4% female). Cox proportional hazards regression was applied to examine associations between hs-CRP and risk of AAA. hs-CRP was treated either as a continuous or a categorical variable (dichotomised at 2 mg/L, 1 mg/L, or median [1.2 mg/L], or as quartiles).

The hazard ratio (HR) of developing AAA per 1 mg/L increase in hs-CRP (continuous hs-CRP) was 1.02 (95% confidence interval [CI] 1.01 - 1.03) in the analysis adjusted for smoking, coronary heart disease, hypertension, diabetes, body mass index, and total cholesterol. Individuals with hs-CRP ≥ 2 mg/L had almost twice the risk of AAA compared with individuals with hs-CRP < 2 mg/L (adjusted HR 1.84, 95% CI 1.51 - 2.25). Dichotomising hs-CRP at a clinical cutoff point of 1 mg/L (adjusted HR 2.13, 95% CI 1.64 -2.76) or at the median of 1.2 mg/L (adjusted HR 2.12, 95% CI 1.62 - 2.76) slightly strengthened the HR. The adjusted HR gradually increased through the ordered hs-CRP quartiles, and was almost four times higher (HR 3.87, 95% CI 2.54 - 5.92) in the highest hs-CRP quartile (hs-CRP > 2.7 mg/L) compared with the lowest quartile (hs-CRP ≤ 0.6 mg/L).

Individuals with elevated hs-CRP had significantly increased risk of developing AAA.