White blood cell count predicts all-cause mortality in patients with suspected peripheral arterial disease

Abstract

Objective: We investigated whether markers of inflammation-white blood cell (WBC) count, C-reactive protein (CRP), and lipoprotein-associated phospholipase A2-are associated with mortality in patients referred for noninvasive lower-extremity arterial evaluation.

Methods: Participants (n = 242, mean age 68 years, 54% men) were followed for a median of 71 months. Ankle-brachial index (ABI), WBC count, plasma CRP, and lipoprotein-associated phospholipase A2 were measured at the start of the study. Factors associated with all-cause mortality were identified using Cox proportional hazards.

Results: During the follow-up period, 56 patients (25%) died. Factors associated with higher mortality were greater age, history of coronary artery disease/cerebrovascular disease, lower ABI, higher serum creatinine, and higher WBC count/plasma CRP. In stepwise multivariable regression analysis, ABI, serum creatinine, WBC count, and CRP were associated significantly with mortality. Patients in the top tertile of WBC count and CRP level had a relative risk of mortality of 3.37 (confidence interval [CI], 1.56-7.27) and 2.12 (CI, 0.97-4.62), respectively. However, only the WBC count contributed incrementally to prediction of mortality. Inferences were similar when analyses were limited to patients with peripheral arterial disease (ABI<0.9, n = 114).

Conclusion: WBC count, but not plasma CRP level, provides incremental information about the risk of death in patients referred for lower-extremity arterial evaluation and in the subset of these patients with peripheral arterial disease.

Figure 1

Kaplan-Meier survival curves based on tertiles of WBC count and plasma levels of CRP and Lp-PLA2