C-reactive protein and endovascular treatment of lower limb peripheral artery disease: an independent prognostic factor.

Purpose: To determine if C-reactive protein (CRP) can predict the outcomes of lower extremity endovascular therapy (EVT) in patients with peripheral artery disease and to calculate a cutoff value that may be useful in identifying patients with a higher risk of EVT failure at 1 year.

Methods: In this prospective single-center study, 121 patients (94 men; mean age 67.7±9.8 years) undergoing EVT of lower limb lesions in an 18-month period were enrolled as a derivation set. In the subsequent 6 months, 53 patients (39 men; mean age 70.1±10.0 years) were enrolled as the validation set. Blood samples were collected before EVT and at 1 month postintervention from both sets of patients to measure CRP levels. The cohorts were followed for 1 year, and data on reinterventions were recorded. A cutoff CRP value was calculated with the highest sensitivity and specificity for EVT failure based on receiver operator characteristic (ROC) curve analysis. The cutoff value was confirmed in the validation set. Cox proportional hazards analysis was performed to evaluate the independent contribution of CRP levels and other variables to the risk of reintervention; results are given as the hazard ratio (HR) and 95% confidence interval (CI).

Results: The area under the ROC curve relating preprocedure CRP levels to 1-year reintervention was 0.77±0.05. The highest likelihood ratio corresponded to a pre-EVT CRP value of 9.8 mg/L (likelihood ratio test=133, df=1, p<0.001). Reintervention before the first year after EVT was related to preprocedure CRP levels (HR 1.1, 95% CI 1.05 to 1.2; p<0.001). These results were confirmed in the validation set (HR 1.1, 95% CI 1.02 to 1.18; p=0.008).

Conclusion: CRP values can be used as an independent marker of EVT outcome. Baseline CRP levels >9.8 mg/L indicate increased risk of secondary interventions, which are often open surgical procedures.