Ankle brachial pressure index but not brachial-ankle pulse wave velocity is a strong predictor of systemic atherosclerotic morbidity and mortality in patients on maintenance hemodialysis

Abstract

Background

Ankle brachial pressure index (ABPI) and pulse wave velocity (PWV) have been widely recognized as a marker of systemic atherosclerosis. We examined whether ABPI and brachial-ankle PWV (baPWV) predict individual cardiovascular events in patients on maintenance hemodialysis (HD).

Methods

We prospectively followed-up 445 HD patients undergoing both ABPI and baPWV measurements for up to 5 years. They were divided into 2 groups [group with ABPI >0.9 to ≤1.3 (n = 328) and group with ABPI ≤0.9 or >1.3 (n = 117)] and were also divided into tertiles according to the baPWV level (T1: <1850 cm/s; T2: 1850–2310 cm/s and T3: ≥2310 cm/s).

Results

During the follow-up period (mean 43 ± 17 months), 206 cardiovascular events [cardiac event: 125 (28.1%), cerebrovascular events: 39 (8.8%), and peripheral arterial events: 42 (9.4%)] occurred, and 36 (8.1%) and 42 (9.4%) patients experienced cardiovascular and non-cardiovascular deaths, respectively. Cox multivariable analysis showed that presence of ABPI ≤0.9 or >1.3 was a significant predictor of cardiac events [hazard ratio (HR) 1.78, 95% confidential interval (CI) 1.27–2.49, p = 0.0008], cerebrovascular event (HR 1.95, 95%CI 1.13–3.36, p = 0.017), peripheral arterial event (HR 3.64, 95%CI 2.10–6.29, p < 0.0001), composite endpoint of cardiovascular events (HR 2.22, 95%CI 1.64–2.99, p < 0.0001), cardiovascular mortality (HR 2.42, 95%CI 1.44–4.06, p = 0.0008) and all-cause mortality (HR 1.52, 95%CI 1.03–2.25, p = 0.037). However, baPWV did not predict cardiovascular events on multivariate analysis.

Conclusion

ABPI but not baPWV is useful for risk stratification of systemic atherosclerotic morbidity and mortality in HD patients. Furthermore, ABPI could predict not only individual peripheral arterial events but also cardiac and cerebrovascular events.

Introduction

The number of patients with end-stage renal failure who need hemodialysis (HD) keep increasing worldwide, and it is said to have reached two million people now [1]. The risk of cardiovascular disease in patients on HD is reportedly 20–30 higher times than the general person [2]. It is thus clear that patients on HD are at an extremely high risk of cardiovascular disease [3]. Moreover the increase in their medical treatment costs becomes a large problem [4], so it is important to predict the risk of cardiovascular disease in the treatment of such population. The number of HD patients also keeps increasing in Japan. Additionally, the high rate of diabetic nephropathy and high age at starting HD therapy are characteristics resulting in an increase in cardiovascular disease in Japan [5].

Ankle brachial pressure index (ABPI) is a useful inspection to diagnose peripheral artery disease (PAD) as recommended in guidelines of Trans Atlantic Inter-Society Consensus II and American College of Cardiology/American Heart Association [6], [7]. PAD is an important manifestation of systemic atherosclerosis, and it is known that patients with ABPI < 0.9 have 3–4 times higher risk of cardiovascular mortality [8]. The utility of ABPI as a predictor of cardiovascular disease is reported not only in general population [9] but also in patients on HD [10], [11], [12], [13]. Studies have shown that aortic pulse wave velocity (PWV) as the index of aortic stiffness is also a strong predictor of cardiovascular disease not only in general population [13] but also in patients with renal insufficiency including HD patients [14], [15], [16], [17]. Recently, it is reported that the measurement of handy brachial-ankle PWV (baPWV) is equally useful with that of aortic PWV [18], [19]. Though ABPI and PWV are strong predictors of cardiovascular disease, studies which compare both modalities are still few. The purpose of the present prospective study was to examine which had stronger predictive power in patients on HD who are at high risk group of cardiovascular disease.