Ankle-arm blood pressure index as a predictor of mortality in hemodialysis patients

Associated risk factors for abnormal ankle-brachial index in hemodialysis patients in a hospital

Ankle-brachial index (ABI) is a marker for peripheral artery disease and can predict mortality in hemodialysis patients. However, it is seldom studied in southern Taiwan, an area with high prevalence of end-stage renal disease (ESRD). The aim of this study was to investigate the prevalence and associated risk factors for peripheral artery disease in the ESRD population in a hospital. All routine hemodialysis patients in one regional hospital were included except for six patients who refused ABI examinations and four patients with atrial fibrillation. Finally, 225 patients formed our study group. ABI was measured using an ABI-form device (Colin VP1000). The prevalence of ABI < 0.9 and > or = 1.3 was 15.6% and 5.8%, respectively. ABI < 0.9 was independently associated with advanced age (p = 0.027), increased pulse pressure (p = 0.005), increased hematocrit (p = 0.008) and decreased serum albumin level (p = 0.009). In addition, ABI > or = 1.3 was significantly associated with diabetes mellitus (p = 0.019). This study demonstrated the associated risk factors of peripheral artery disease in patients with hemodialysis in a hospital. ESRD patients of advanced age and with increased pulse pressure, increased hematocrit and decreased serum albumin level had a relatively high risk for ABI < 0.9 and patients with diabetes had a relatively high risk for ABI > or = 1.3.

Combined effect of chronic kidney disease and peripheral arterial disease on all-cause mortality in a high-risk population

BACKGROUND AND OBJECTIVES

Chronic kidney disease (estimated glomerular filtration rate <60 ml/min per 1.73 m(2)) and peripheral arterial disease (ankle-brachial index <0.9) independently predict mortality. It was hypothesized that the risk for death is higher in patients with both chronic kidney disease and peripheral arterial disease compared with those with chronic kidney disease or peripheral arterial disease alone.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 1079 patients who had an ankle-brachial index and serum creatinine recorded within 90 d of each other in 1999 were studied retrospectively. Glomerular filtration rate was estimated using the Modification of Diet in Renal Disease equation. Patients were categorized into four groups: Chronic kidney disease and peripheral arterial disease, chronic kidney disease alone, peripheral arterial disease alone, or no chronic kidney disease or peripheral arterial disease.

RESULTS

The overall 6-yr mortality rate was 28% (n = 284). Patients with both chronic kidney disease and peripheral arterial disease had the highest mortality rate (45%) compared with patients with chronic kidney disease alone (28%), peripheral arterial disease alone (26%), and neither condition (18%). After adjustment for clinical and demographic variables, the chronic kidney disease and peripheral arterial disease group had an increased odds for death when compared with the no chronic kidney disease or peripheral arterial disease group or the single disease groups.

CONCLUSIONS

These findings indicate that patients with both chronic kidney disease and peripheral arterial disease have a significantly higher risk for death than patients with either disease alone.

Novel and traditional cardiovascular risk factors for peripheral arterial disease in incident-dialysis patients

Peripheral arterial disease (PAD), which threatens limb viability and patient survival, is increasing in frequency in the dialysis population, but associated risk factors remain poorly defined. We conducted a cross-sectional analysis of the association of novel and traditional cardiovascular risk factors with PAD in incident-dialysis patients enrolled in the CHOICE study by application of multivariate logistic-regression models with adjustment for confounders. Risk factors were determined by interview, record review, and laboratory analysis of frozen specimens. Among 922 patients, 25% had a diagnosis of PAD. After adjustment, higher prevalence of PAD was associated with increasing age (odds ratio [OR], 95% CI = 1.28 [range: 1.12 to 1.48] per 10-year increase in age); presence of diabetes mellitus (OR, 95% CI = 2.76 [range: 1.72 to 4.42]); higher Index of Co-Existent Disease (ICED), ICED 2 and ICED 3 versus ICED 0-1, (OR, 95% CI = 2.04; [range: 1.24 to 3.35] and OR, 95% CI = 2.81 [range: 1.83 to 4.30], respectively). After adjustment, we found no statistically significant association between CRP and prevalence of PAD. The prevalence of PAD diagnosis was 34% higher per quartile increase in Lp(a) (OR, 95% CI = 1.34 [range: 1.13 to 1.59]). Similarly, the prevalence of PAD diagnosis was 19% higher per quartile increase in total homocysteine (OR, 95% CI = 1.19 [range: 1.05 to 1.35]). The prevalence of PAD is high in incident-dialysis patients and is associated with several novel and traditional cardiovascular risk factors. This study identifies several novel risk factors (eg, Lp(a) and total homocysteine) and underscores the need for further research to reduce the burden of PAD in this high-risk group of patients.

Peripheral Arterial Disease: A Guide for Nephrologists

Cardiovascular disease is a major source of morbidity and mortality for patients with chronic kidney disease (CKD). Peripheral arterial disease (PAD) is a strong predictor of coronary artery disease and a risk factor for mortality in the general population. This is of particular interest to nephrologists because the risk for PAD is increased in CKD. Often, PAD is overlooked as a source of morbidity and as a cardiovascular risk factor in this population. This review serves as an overview of the epidemiology, screening, diagnosis, and treatment of PAD with an emphasis on CKD.

Determinants of Arterial Wall Stiffness and Peripheral Artery Occlusive Disease in Nondiabetic Hemodialysis Patients

Aortic pulse wave velocity (Ao-PWV) and ankle-brachial blood pressure index (ABPI) are significant prognostic factors in patients with end-stage renal disease (ESRD). Diabetes mellitus (DM) promotes changes in arterial walls, including marked increases in Ao-PWV and decreases in ABPI. To determine the prevalence of peripheral arterial occlusive disease (PAOD) as well as the clinical variables useful in predicting these changes in nondiabetic patients with ESRD undergoing hemodialysis (HD), we performed a cross-sectional study in a cohort of 143 patients. Ao-PWV and ABPI were measured simultaneously and compared with several annual biochemical measurements and other clinical variables. The prevalence of PAOD in our cohort was 30.5%. In univariate regression analysis, Ao-PWV correlated positively with age, heart rate (HR), blood pressure (BP), pulse pressure (PP) and HbA1c, and negatively with serum albumin and ABPI. ABPI correlated negatively with age, HD duration, systolic BP, PP, low-density lipoprotein (LDL) cholesterol and hypersensitive C-reactive protein (hs-CRP), and positively with serum albumin and bone mineral density. In a step-down multiple regression analysis, HbA1c was identified as an independent determinant of Ao-PWV along with age, HD duration, HR and mean BP, while hs-CRP was an independent contributor to ABPI along with age, HD duration, PP and LDL cholesterol. Our results suggest that HD promotes aortic wall stiffness and PAOD progression. We recommend the monitoring of HbA1c to allow the prediction of aortic wall stiffness in nondiabetic ESRD patients. Our results did not confirm the influence of insulin resistance on the development of arterial sclerosis lesions.

Mortality and cardiovascular risk across the ankle-arm index spectrum: results from the Cardiovascular Health Study

BACKGROUND

A low ankle-arm index (AAI) is a strong predictor of mortality and cardiovascular events. A high AAI also appears to be associated with higher mortality risk in select populations. However, mortality and cardiovascular risk across the AAI spectrum have not been described in a more broadly defined population.

METHODS AND RESULTS

We examined total and cardiovascular mortality and cardiovascular events across the AAI spectrum among 5748 participants in the Cardiovascular Health Study (CHS). The mean age of the sample population was 73+/-6 years, and the sample included 3289 women (57%) and 883 blacks (15%). The median duration of follow-up was 11.1 (0.1 to 12) years for mortality and 9.6 (0.1 to 12.1) years for cardiovascular events. There were 2311 deaths (953 of which were cardiovascular) and 1491 cardiovascular events during follow-up. After adjustment for potential confounders, AAI measurements < or =0.60 (hazard ratio [HR] 1.82, 95% CI 1.42 to 2.32), 0.61 to 0.7 (HR 2.08, 95% CI 1.61 to 2.69), 0.71 to 0.8 (HR 1.80, 95% CI 1.44 to 2.26), 0.81 to 0.9 (HR 1.73 95% CI 1.43 to 2.11), 0.91 to 1.0 (HR 1.40, 95% CI 1.20 to 1.63), and >1.40 (HR 1.57, 95% CI 1.07 to 2.31) were associated with higher mortality risk from all causes compared with the referent group (AAI 1.11 to 1.20). The pattern was similar for cardiovascular mortality. For cardiovascular events, risk was higher at all AAI levels <1 but not for AAI levels >1.4 (HR 1.00, 95% CI 0.57 to 1.74). The association of a high AAI with mortality was stronger in men than in women and in younger than in older cohort members.

CONCLUSIONS

In a cohort of community-dwelling elders, mortality risk was higher than the referent category of 1.11 to 1.2 among participants with AAI values above the traditional cutpoint of 0.9 (ie, 0.91 to 1.0 and >1.4), and the specific association of AAI with mortality varied by age and gender.

Management of peripheral arterial disease in chronic kidney disease

PAD has been overlooked in many epidemiologic studies evaluating cardiovascular risk associated with renal disease. Conversely, CKD has not been evaluated as a potential risk factor in epidemiologic studies of PAD. PAD, however,seems to be more prevalent among patients with even moderate CKD than in the general population and is most common among chronic dialysis patients, one third or more of whom have a low ABI. Patients with CKD also seem to be at increased risk for developing claudication and for requiring surgical intervention for lower extremity PAD. Furthermore, even moderate CKD seems to be a risk factor for postoperative death and complications after both lower extremity amputation and revascularization procedures. Conversely, even asymptomatic PAD seems to be a risk factor for death among dialysis patients. In the general population, statins, antiplatelet agents (particularly clopidogrel), antihypertensive agents, and ACE inhibitors all have a proven benefit in reducing cardiovascular events in patients with PAD and in some instances may also reduce PAD events. Available evidence suggests that patients with CKD also experience cardio-vascular risk reduction with statin and ACE-inhibitor therapy, but these therapies have not been shown to reduce PAD events specifically in patients with CKD. Further studies are needed to identify interventions that can specifically reduce the incidence of PAD complications in patientswith CKD. Although it is clear that mortality and complication rates after both lower extremity amputation and revascularization are increased in patients with even moderate CKD, currently available observational studies do not provide clear guidance for surgical decision making in CKD patients with limb-threatening ischemia. Further studies are needed to evaluate the risksand benefits of amputation over revascularizationamong patients with CKD and to investigatereasons for the high mortality associated with these procedures in this patient group. Further studies are also needed to measure the impact of CKD on care processes for PAD with the goal of identifying target areas for improvement.

Cardiovascular calcification in Hispanic Americans (HA) with chronic kidney disease (CKD) due to type 2 diabetes

BACKGROUND

Cardiovascular calcification (CVC) is common and severe in patients with end-stage renal disease on dialysis. However, the prevalence and severity of CVC is less well documented in patients with chronic kidney disease (CKD) not yet on dialysis.

METHODS

Fifty-eight nondialyzed HA with type 2 diabetes and CKD were enrolled. They comprise 29 patients with stages 1 and 2 CKD (early CKD group) and 26 patients with stages 4 and 5 CKD (advanced CKD group). Coronary artery calcification (CAC) was measured by ultrafast spiral computed tomography, while peripheral artery calcification (PAC) was evaluated by plain x-ray of the chest, pelvis, thighs, and lower extremities.

RESULTS

The prevalence of CAC and PAC were significantly higher in the advanced CKD group compared to the early CKD group (73% vs. 38%; P < 0.01 and 85% vs. 35%; P < 0.0001, respectively). The median CAC scores were 18-fold greater in the advanced CKD group (138.9 vs. 7.8, respectively). By linear regression analysis, a strong association was found between the level of renal function and ln total volume of CAC.

CONCLUSION

Our data indicate that CAC and PAC are common and severe in HA diabetic patients with CKD not previously treated with dialysis, calcium-based phosphate binders, or vitamin D analogues. Lower level of renal function is associated with increased burden of vascular calcification in predialysis patients with CKD.

The Validity, Reliability, Reproducibility and Extended Utility of Ankle to Brachial Pressure Index in Current Vascular Surgical Practice

BACKGROUND

Despite the increasing sophistication of vascular surgical practice, more than three decades after its introduction to clinical practice, the ankle to brachial pressure index (ABPI) remains the cornerstone of non-invasive assessment of the patient with symptomatic peripheral arterial disease (PAD).

AIM

To summarise what is known about ABPI and critically appraise its validity, reliability, reproducibility and extended utility.

METHODS

A MEDLINE (1966-2004) and Cochrane library search for articles relating to measurement of ABPI was undertaken; see text for further details.

RESULTS

There is considerable disagreement as to how ABPI should be measured. Furthermore, various factors, including the type of equipment used, and the experience of the operator, can result in significant inter- and intra-observer error. As such, care must be taken when interpreting data in the literature. ABPI is valuable in the assessment of patients with atypical symptoms, venous leg ulcers and after vascular and endovascular interventions. However, absolute pressures are probably more valuable in patients with critical limb ischaemia. ABPI is also useful in subjects with asymptomatic PAD where it correlates well with, and may be used in screening studies to quantify, cardiovascular risk.

CONCLUSIONS

While its apparent simplicity can beguile the unwary, ABPI will continue to have a key role in the assessment of symptomatic PAD. ABPI is also likely to have extended utility in health screening and institution of best medical therapy in asymptomatic subjects.

Atherosclerotic and hemostatic abnormalities in patients undergoing hemodialysis

Vascular events caused by atherosclerosis are the major cause of death in patients undergoing hemodialysis (HD). The relationship between the tests of atherosclerosis and hemostasis in 84 patients with HD was examined. Abnormal test results indicting the occurrence of atherosclerosis were found in 66% by the Fontaine score, in 33% by ankle blood pressures, and in 79% by aortic calcification index (ACI). When HD was prolonged, the mean Fontaine score and ACI were further increased. Particularly, the ACI tended to correlate with HD duration. The ankle-brachial index (ABI) was decreased in patients with HD duration of more than 10 years. Before HD, the plasma levels of fibrinogen, plasmin-plasmin inhibitor complex (PIC), thrombomodulin (TM), and D-dimer were increased, while the plasma levels of protein C (PC), antithrombin (AT), thrombin-antithrombin complex (TAT), and tissue plasminogen activator (tPA)-plasminogen activator inhibitor-I (PAI-I) complex (tPA-PAI-1 complex) were decreased. With prolonged HD, the plasma levels of AT and PC were decreased, while those of D-dimer were increased. The plasma levels of TAT and TPA-PAI-1 complex were significantly increased and those of PIC, soluble fibrin (SF) and D-dimer tended to be high in patients with less than 0.7 of ABI. The plasma levels of D-dimer, TPA-PAI-1 complex, TAT, PIC, and SF tended to be high in patients with more than 0.5 in ABI. These findings suggest that patients undergoing HD have progressive atherosclerosis and that this is associated with some hemostatic abnormalities.

Peripheral vascular disease risk factors among patients undergoing hemodialysis

Peripheral vascular disease (PVD) is common among patients undergoing hemodialysis, but little is known regarding the risk factors for PVD in this population. Data from waves 1, 3, and 4 of the United States Renal Data System Dialysis Morbidity and Mortality Study were used to examine cross-sectional associations of a range of conventional cardiovascular risk factors and uremia- or dialysis-related variables with PVD. Univariate and multivariate logistic regression models were developed using wave 3 and 4 data. Odds ratios for the multivariate model derived using wave 3 and 4 data were then compared with those obtained with the wave 1 data set. For both data sets, PVD was positively associated with the duration of dialysis (vintage) and malnourished status and was negatively associated with serum albumin and parathyroid hormone levels and predialysis diastolic BP. Kt/V was negatively associated with PVD in waves 3 and 4 but not in wave 1. PVD was associated with increasing age, white (versus non-white) race, male gender, diabetes mellitus, coronary artery disease, cerebrovascular disease, smoking, and left ventricular hypertrophy, as for the general population, but not with hypertension or hyperlipidemia. In conclusion, PVD among hemodialysis patients is associated with both dialysis-specific variables and most conventional cardiovascular risk factors other than hypertension and hyperlipidemia. Future studies should prospectively examine the association of these variables identified in cross-sectional analyses with the de novo development of PVD in this population.

Lower-extremity peripheral arterial disease among patients with end-stage renal disease

Peripheral arterial occlusive disease (PAOD) accounts for significant morbidity and mortality among end-stage renal disease (ESRD) patients but has not been as extensively studied as other kinds of atherosclerotic disease in this population. The current epidemiology and management of PAOD in ESRD patients is here reviewed and target areas for future research are identified. The prevalence of PAOD appears to be much higher among ESRD patients than in the general population. Risk factors for disease among ESRD patients are not well understood but probably include both conventional and dialysis or uremia-associated risk factors. Standard diagnostic techniques used to identify PAOD in the general population may not be as helpful in ESRD patients because many of these tests are inaccurate in the settings of vascular calcification and small-vessel disease. Despite the fact that this is a common disease in ESRD patients, most of these patients are not screened for PAOD. Interventions that have proven effective in the prevention and treatment of PAOD in the general population, such as smoking cessation, preventive foot care, and exercise, have not been systematically applied to ESRD patients. Furthermore, the optimal management of ischemic ulceration and gangrene in ESRD patients is quite controversial, and better algorithms for the prevention and management of PAOD in ESRD patients are needed. In conclusion, PAOD is common in ESRD patients. Future research should identify risk factors for disease in this population, and efforts should be made to develop strategies for the effective prevention and management of limb ischemia in this population.