Prognostic value of Wound, Ischemia and foot Infection (WIfI) score after lower extremities bypass surgery for peripheral artery disease in chronic hemodialysis patients

Abstract

Abstract Background Although lower extremities bypass surgery has been commonly performed to treat peripheral artery disease (PAD) even in patients on hemodialysis (HD) as well as general population, poorer prognosis in such subjects still remains major problems compared to non-HD population. Recently, Wound, Ischemia and foot Infection (WIfI) scoring system has been developed for classification of lower extremity threatened limb to impact amputation risk. However, the utility of predictability still remain unclear in HD patients. The aim of this study is to clarify the characteristics of the WIfI score and its prognostic value after bypass surgery in such patients with PAD. Methods Pre-procedural threatened limb grade in consecutive 361 patients (224 HD patients and 137 non-HD patients) undergoing successfully bypass surgery were assessed using the WIfI scoring system. Primary outcome was amputation-free survival (AFS) defined as freedom from major amputation and/or all-cause mortality. They were followed-up for 5 years. Results Although ischemia grade ≥ 2 was comparable between HD and non-HD patients (97.8% vs. 99.2%, p=0.74), wound grade and infection grade ≥ 2 were significantly higher prevalent in HD patients than in non-HD patients (56.7% vs. 32.8%, p<0.0001 and 53.1% vs. 30.7%, p<0.0001, respectively). The AFS rate for 5-year was 72.6%, 46.5%, 44.4% and 32.7% in wound grade 0, 1, 2 and 3 [adjusted hazard ratio (aHR) 3.67, 95% confidence interval (CI) 1.67-8.31, p=0.0009 for grade 3 vs. grade 0], and was 57.0%, 57.8%, 45.7% and 19.4% in infection grade 0, 1, 2 and 3 (aHR 2.71, 95% CI 1.35-5.32, p=0.0052 for grade 3 vs. grade 0) in HD patients, respectively. However, even in subgroup without any wound, HD patients had markedly poorer AFS (vs. 100% in non-HD, p<0.0001) compared to non-HD patients. Also in patients without any infection, similar results were obtained (vs. 95.3% in non-HD, aHR 13.7, 95% CI 3.12-60.5, p=0.0005). HD was also consistently identified as a strong risk factor for poor AFS (aHR 2.83, 95% CI 1.67-5.09, p<0.0001). Conclusion Wound and foot infection grade as components of the WIfI score could stratify the risk of amputation and/or mortality after bypass surgery even in HD patients. Severity of wound or infection status was higher in HD patients compared to non-HD patients, however, high risk of poor AFS even without any wound or infection should be paid attention in this high-risk population.