Serum bilirubin level is negatively correlated with disease progression of peripheral arterial disease: an observational cohort study.

We determined whether low bilirubin level is a risk factor for peripheral arterial disease (PAD). We recruited 318 patients with PAD and 100 healthy volunteers. Patients were divided into 4 groups by the Fontaine classification for PAD, namely, group 1 (grade 1, n = 4); group 2 (grade 2, n = 114), group 3 (grade 3, n = 164), and group 4 (grade 4, n = 36). Total bilirubin (T-BIL), direct bilirubin (D-BIL), and indirect bilirubin (I-BIL) levels were compared using stepwise multiple regressions adjusted for selected factors. After adjusting for gender, age, smoking, and diastolic blood pressure, serum levels of T-BIL, D-BIL, and I-BIL were significantly lower in the PAD group (P < .05). Patients with grade 4 PAD showed significantly (P < .05) lower levels of T-BIL when compared with grade 2 patients. We concluded that serum bilirubin levels are negatively correlated with the severity and progression of PAD.