Elevated High Sensitivity C Reactive Protein and Risk of Abdominal Aortic Aneurysm: A Prospective Population Based Study in The Norwegian HUNT Study.

Abstract

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.