Platelet dysfunction and end-stage renal disease

Cutaneous manifestations of ESRD

A broad range of skin diseases occurs in patients with ESRD: from the benign and asymptomatic to the physically disabling and life-threatening. Many of them negatively impact on quality of life. Their early recognition and treatment are essential in reducing morbidity and mortality. The cutaneous manifestations can be divided into two main categories: nonspecific and specific. The nonspecific manifestations are commonly seen and include skin color changes, xerosis, half-and-half nails, and pruritus. The specific disorders include acquired perforating dermatosis, bullous dermatoses, metastatic calcification, and nephrogenic systemic fibrosis. This review article describes these conditions and considers the underlying pathophysiology, clinical presentations, diagnosis, and treatment options.

Safety of Percutaneous Tunneled Hemodialysis Catheter Procedures in Patients Receiving Concurrent Clopidogrel Therapy

Purpose

Patients on clopidogrel are at increased risk of bleeding. This study was commenced to assess the incidence of bleeding in dialysis patients who underwent tunneled hemodialysis catheter procedures while on clopidogrel therapy.

Methods

This is a single center retrospective study of 25 (10 men, 15 women; median age 70) dialysis patients in whom clopidogrel could not be discontinued and underwent tunneled hemodialysis catheter insertion, removal or exchange between the period March 2010 to November 2011. The medical records of patients were reviewed and complications were classified according to the Society of Interventional Radiology system. Fifty-three procedures (22 insertions, 11 exchanges and 20 removals) were performed in these patients. The pre-procedural median platelet count, International Normalized Ratio and partial thromboplastin time were 195×103/dL (range 50-666), 1.1 (range 0.9-3.3) and 26.3 seconds (range 22.5-69.8) respectively.

Results and Conclusions

Forty-six procedures were performed in patients on clopidogrel and aspirin treatment. Five procedures were performed in patients while on clopidogrel in combination with aspirin and warfarin, and two procedures were performed with patients on clopidogrel alone. There were no documented bleeding complications from tunneled hemodialysis catheter procedures performed in patients on concurrent clopidogrel therapy in our study. Further prospective assessment with a larger cohort is necessary in order to validate these findings.

Characteristics of the small bowel lesions detected by capsule endoscopy in patients with chronic kidney disease

Obscure gastrointestinal bleeding (OGIB) is one of the common complications in patients with chronic kidney disease (CKD), especially those who are on maintenance hemodialysis (HD). However, little is known about the characteristics of the small-bowel lesions in these patients, or of the factors that could predict the presence of such lesions. Therefore we enrolled a total of 42 CKD patients (including 19 HD patients and 23 non-HD patients), and compared the incidence of the small-bowel lesions among two groups. Furthermore, to identify predictive factors for the presence of small-bowel lesions, we performed multivariate logistic-regression-analyses. The incidence of small-bowel vascular lesions was significantly higher in CKD patients than in age-and-sex matched non-CKD patients (P < 0.001). On the other hand, there was any significant difference of the incidence of small-bowel lesions between HD and non-HD patients. In CKD patients, past history of blood transfusion (OR 5.66; 95% CI 1.10–29.1, P = 0.04) was identified as an independent predictor of the presence of vascular lesions, and history of low-dose aspirin use (OR 6.00; 95% CI 1.13–31.9, P = 0.04) was identified as that of erosive/ulcerated lesions. This indicated that proactive CE examination would be clinically meaningful for these patients.

Elevated levels of procoagulant plasma microvesicles in dialysis patients

Cardiovascular (CV) death remains the largest cause of mortality in dialysis patients, unexplained by traditional risk factors. Endothelial microvesicles (EMVs) are elevated in patients with traditional CV risk factors and acute coronary syndromes while platelet MVs (PMVs) are associated with atherosclerotic disease states. This study compared relative concentrations of circulating MVs from endothelial cells and platelets in two groups of dialysis patients and matched controls and investigated their relative thromboembolic risk. MVs were isolated from the blood of 20 haemodialysis (HD), 17 peritoneal dialysis (PD) patients and 20 matched controls. Relative concentrations of EMVs (CD144(+ ve)) and PMVs (CD42b(+ ve)) were measured by Western blotting and total MV concentrations were measured using nanoparticle-tracking analysis. The ability to support thrombin generation was measured by reconstituting the MVs in normal plasma, using the Continuous Automated Thrombogram assay triggered with 1µM tissue factor. The total concentration of MVs as well as the measured sub-types was higher in both patient groups compared to controls (p<0.05). MVs from HD and PD patients were able to generate more thrombin than the controls, with higher peak thrombin, and endogenous thrombin potential levels (p<0.02). However there were no differences in either the relative quantity or activity of MVs between the two patient groups (p>0.3). Dialysis patients have higher levels of circulating procoagulant MVs than healthy controls. This may represent a novel and potentially modifiable mediator or predictor of occlusive cardiovascular events in these patients.

Hemostasis in acute liver and kidney failure: nothing is as it seems

Very little is known about the behavior of the hemostatic system in patients with acute kidney injury (AKI) associated with acute liver failure (ALF). Agarwal and colleagues show that patients who suffer from both ALF and AKI exhibit a higher degree of hemostasis impairment than those with normal renal function. Both anticoagulant and procoagulant factors were impaired. The development of AKI appears to displace the hemostatic equilibrium toward a more prothrombotic pattern.

Whole blood platelet aggregation and release reaction testing in uremic patients

Background. Platelet function analysis utilizing platelet-rich plasma and optical density based aggregometry fails to identify patients at risk for uremia associated complications. Methods. We employed whole blood platelet aggregation analysis based on impedance as well as determination of ATP release from platelet granules detected by a chemiluminescence method. Ten chronic kidney disease (CKD) stage 4 or 5 predialysis patients underwent platelet evaluation. Our study aims to evaluate this platform in this patient population to determine if abnormalities could be detected. Results. Analysis revealed normal aggregation and ATP release to collagen, ADP, and high-dose ristocetin. ATP release had a low response to arachidonic acid (0.37 ± 0.26 nmoles, reference range: 0.6–1.4 nmoles). Platelet aggregation to low-dose ristocetin revealed an exaggerated response (20.9 ± 18.7 ohms, reference range: 0–5 ohms). Conclusions. Whole blood platelet analysis detected platelet dysfunction which may be associated with bleeding and thrombotic risks in uremia. Diminished ATP release to arachidonic acid (an aspirin-like defect) in uremic patients may result in platelet associated bleeding. An increased aggregation response to low-dose ristocetin (a type IIb von Willebrand disease-like defect) is associated with thrombus formation. This platelet hyperreactivity may be associated with a thrombotic diathesis as seen in some uremic patients.

Major bleeding events and risk stratification of antithrombotic agents in hemodialysis: results from the DOPPS

Benefits and risks of antithrombotic agents remain unclear in the hemodialysis population. To help clarify this we determined variation in antithrombotic agent use, rates of major bleeding events, and factors predictive of stroke and bleeding in 48,144 patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases I-IV. Antithrombotic agents including oral anticoagulants (OACs), aspirin (ASA), and anti-platelet agents (APAs) were recorded along with comorbidities at study entry, and clinical events including hospitalization due to bleeding were then collected every 4 months. There was wide variation in OAC (0.3-18%), APA (3-25%), and ASA use (8-36%), and major bleeding rates (0.05-0.22 events/year) among countries. All-cause mortality, cardiovascular mortality, and bleeding events requiring hospitalization were elevated in patients prescribed OACs across adjusted models. The CHADS2 score predicted the risk of stroke in atrial fibrillation patients. Gastrointestinal bleeding in the past 12 months was highly predictive of major bleeding events; for patients with previous gastrointestinal bleeding, the rate of bleeding exceeded the rate of stroke by at least twofold across all categories of CHADS2 score, including patients at high stroke risk. Appropriate risk stratification and a cautious approach should be considered before OAC use in the dialysis population.

Aspects of platelet disturbances in haemodialysis patients

Patients with mild-to-chronic kidney disease (CKD) exhibit a variety of haemostatic disorders, ranging from an increased clotting tendency and reductions in the levels of natural inhibitors of coagulation to defective fibrinolysis. In addition, platelet (PLT) abnormalities are common. In this minireview, we report on aspects of haemodialysis (HD)-induced PLT activation. It is demonstrated that PLTs from HD patients are exhausted due to repeated stimulation of HD treatment and recurrent release of PLT degranulation products. During HD, additional aberrations of the haemostatic process occur. Besides deviations of coagulation and fibrinolysis, PLT activation and a reduction in their granule content have been observed during HD treatment. As HD treatment is carried out three times per week, month after month, chronic HD patients may suffer persistently from coagulation defects and PLT disorders on top of the alterations induced by the uraemic state itself. PLT activation occurs together with thrombin and fibrin generation. However, macro fibrin depositions in clot devices are not demonstrated, microaggregates occur not only in the extracorporeal circuit (ECC) but are also present in the blood circulation. As vascular access thrombosis is a frequent complication in patients with HD treatment, it is believed that hypercoagulability could result from vascular changes combined with PLTs and activation of coagulation factors.

Nonpeptic ulcer, nonvariceal gastrointestinal bleeding in hemodialysis patients

OBJECTIVES

Hemodialysis patients carry a higher risk of peptic ulcer bleeding. Whether hemodialysis patients also have a higher occurrence of nonpeptic ulcer, nonvariceal gastrointestinal bleeding needs further evaluation.

METHODS

Using Taiwan's National Health Insurance research database, the occurrence of nonpeptic ulcer, nonvariceal gastrointestinal bleeding was compared among the hemodialysis patients, chronic kidney disease patients, and controls using log-rank test. Risk factors were identified by Cox regression analysis.

RESULTS

A total of 20,830 patients were enrolled, including 8210 hemodialysis and 4190 chronic kidney disease patients and 8430 age- and sex-matched controls in a 2:1:2 ratio. In the 7-year follow-up period, hemodialysis patients had a significantly higher cumulative hazard of nonpeptic ulcer, nonvariceal gastrointestinal bleeding than chronic kidney disease patients and controls (P <.001, by log-rank test). The hazard also was significantly higher in the chronic kidney disease patients than in controls. Cox regression analysis revealed that older age, the comorbidities of diabetes mellitus, cirrhosis, and chronic obstructive pulmonary disease, history of uncomplicated peptic ulcer disease, chronic kidney disease (hazard ratio 5.17), hemodialysis (hazard ratio 9.43), and use of selective serotonin reuptake inhibitors were independent risk factors for nonpeptic ulcer, nonvariceal gastrointestinal bleeding in all study patients. Old age, diabetes mellitus, cirrhosis, chronic obstructive pulmonary disease, history of uncomplicated peptic ulcer disease, and use of selective serotonin reuptake inhibitors were independent risk factors in hemodialysis patients.

CONCLUSIONS

There is a higher risk of developing nonpeptic ulcer, nonvariceal gastrointestinal bleeding in hemodialysis patients after adjustments for age, sex, underlying comorbidities, and ulcerogenic medication. The risk has increased since patients had chronic kidney disease.

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet treatment may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased.

OBJECTIVES

To summarise the effects of antiplatelet treatment (antiplatelet agent versus control or other antiplatelet agent) for the prevention of cardiovascular and adverse kidney outcomes in individuals with CKD.

SEARCH METHODS

In January 2011 we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Cochrane Renal Group's Specialised Register without language restriction.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet treatment versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data was pooled using the random-effects model.

MAIN RESULTS

We included 50 studies, enrolling 27,139 participants; 44 studies (21,460 participants) compared an antiplatelet agent with placebo or no treatment, and six studies (5679 participants) directly compared one antiplatelet agent with another. Compared to placebo or no treatment, antiplatelet agents reduced the risk of myocardial infarction (17 studies; RR 0.87, 95% CI 0.76 to 0.99), but not all-cause mortality (30 studies; RR 0.93, 95% CI 0.81 to 1.06), cardiovascular mortality (19 studies; RR 0.89, 95% CI 0.70 to 1.12) or stroke (11 studies; RR 1.00, 95% CI 0.58 to 1.72). Antiplatelet agents increased the risk of major (27 studies; RR 1.33, 95% CI 1.10 to 1.65) and minor bleeding (18 studies; RR 1.49, 95% CI 1.12 to 1.97). In terms of dialysis access outcomes, antiplatelet agents reduced access thrombosis or patency failure but had no effect on suitability for dialysis. Meta-regression analysis indicated no differences in the relative benefit or harms of treatment (risk of all-cause mortality, myocardial infarction, or major bleeding) by type of antiplatelet agent or stage of CKD. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, treatment in kidney transplant recipients, primary prevention, or risk of ESKD.

AUTHORS' CONCLUSIONS

Antiplatelet agents reduce myocardial infarction but increase major bleeding. Risks may outweigh harms among people with low annual risks of cardiovascular events, including those with early stages of CKD who do not have clinically-evident occlusive cardiovascular disease.

In-hospital mortality risk estimation in patients with acute nonvariceal upper gastrointestinal bleeding undergoing hemodialysis: a retrospective cohort study

BACKGROUND

Upper gastrointestinal bleeding (UGIB) is a major cause of clinical bleeding among patients with end-stage renal disease (ESRD). This study aimed to investigate the association between mortality and UGIB in patients with uremia.

METHODS

From 2004 to 2010, a tertiary hospital-based retrospective cohort comprising 322 patients undergoing hemodialysis was investigated. All the patients were diagnosed with UGIB according to the International Classification of Diseases, 9th Revision (ICD-9) that included peptic ulcer bleeding, duodenal ulcer bleeding, and other symptoms. UGIB was required to be one of the first three discharge diagnoses. Rehospitalization within 3 days after discharge was regarded as the same course. Exclusion criteria were age <20 years, previous gastric resection or vagotomy, esophageal and gastric variceal bleeding, or gastric cancer within the first 2 years of the index hospitalization.

RESULTS

The all-cause in-hospital mortality rate of patients with UGIB undergoing hemodialysis was high, with the first-month mortality rate of 13.7%, sixth-month mortality rate of 26.7%, and first-year mortality rate of 27.0%. Using Cox regression models, we found that the high mortality rate of the UGIB group was significantly correlated with older age [adjusted hazard ratio (HR) = 1.02, 95% confidence interval (CI) = 1.01-1.04], female sex (adjusted HR = 1.62, 95% CI = 1.05-2.51), infection during hospitalization (adjusted HR = 1.85, 95% CI = 1.13-3.03), single episodic UGIB (adjusted HR = 2.00, 95% CI = 1.08-3.70), abnormal white blood cell (WBC) count (adjusted HR = 1.59, 95% CI = 1.03-2.45), and albumin level ≤3 g/dL (adjusted HR = 2.67, 95% CI = 1.51-4.72).

CONCLUSION

In conclusion, patients with ESRD who are admitted with primary UGIB have a profoundly increased risk of all-cause in-hospital mortality during the follow-up period.

Diagnosis of common dermopathies in dialysis patients: a review and update

Cutaneous abnormalities in patients with end-stage renal disease (ESRD) receiving hemodialysis or peritoneal dialysis may demonstrate signs of their underlying condition or reveal associated disease entities. While a thorough examination of the scalp, skin, mucosa, and nails is integral to establishing a diagnosis, certain conditions will resolve only with dialysis or improvement of their renal disease and others may not require or respond to treatment. Half and half nails, pruritus, xerosis, and cutaneous hyperpigmentation are common manifestations in ESRD. With hemodialysis, uremic frost is no longer prevalent in ESRD patients and ecchymoses have decreased in incidence. Acquired perforating dermatoses are seen in over one-tenth of hemodialysis patients. Metastatic calcinosis cutis and calciphylaxis are both rarely reported, although the latter is seen almost exclusively in the setting of hemodialysis. Diagnosis of nephrogenic systemic fibrosis has historically been challenging; as such, new diagnostic criteria have been proposed. Blood porphyrin profiles are needed to differentiate between porphyria cutanea tarda and pseudoporphyria. We will review and provide an update on the aforementioned common cutaneous manifestations of ESRD in patients receiving dialysis.

Flank pain, nausea, vomiting and hypotension in a chronic hemodialysis patient with a spontaneous perirenal hemorrhage

Decreases in blood pressure develop in response to a wide range of clinical disorders. Various factors have been implicated in the development of hemodialysis-associated hypotension, including an impairment of the compensatory processes, an autonomic dysfunction or cardiac failure. The additional presence of concomitant acute abdomen may result in a diagnostically challenging situation. We herein report our experience with a chronic hemodialysis patient who developed severe hypotension with acute flank pain due to spontaneous bleeding around the kidney. Concerns regarding the management of the disease are also discussed.

Managing cardiovascular risk in people with chronic kidney disease: a review of the evidence from randomized controlled trials

Cardiovascular disease is the leading cause of death and morbidity in people with chronic kidney disease (CKD) making measures to modify cardiovascular risk a clinical priority. The relationship between risk factors and cardiovascular outcomes is often substantially different in people with CKD compared with the general population, leading to uncertainty around pathophysiological mechanisms and the validity of generalizations from the general population. Furthermore, published reports of subgroup analyses from clinical trials have suggested that a range of interventions may have different effects in people with kidney disease compared with those with normal kidney function. There is a relative scarcity of randomized controlled trials (RCTs) conducted in CKD populations, and most such trials are small and underpowered. As a result, evidence to support cardiovascular risk modification measures for people with CKD is largely derived from small trials and post hoc analyses of RCTs conducted in the general population. In this review, we examine the available RCT evidence on interventions aimed at preventing cardiovascular events in people with kidney disease to identify beneficial treatments as well as current gaps in knowledge that should be a priority for future research.

Platelets of patients with chronic kidney disease demonstrate deficient platelet reactivity in vitro

Background

In patients with chronic kidney disease studies focusing on platelet function and properties often are non-conclusive whereas only few studies use functional platelet tests. In this study we evaluated a recently developed functional flow cytometry based assay for the analysis of platelet function in chronic kidney disease.

Methods

Platelet reactivity was measured using flow cytometric analysis. Platelets in whole blood were triggered with different concentrations of agonists (TRAP, ADP, CRP). Platelet activation was quantified with staining for P-selectin, measuring the mean fluorescence intensity. Area under the curve and the concentration of half-maximal response were determined.

Results

We studied 23 patients with chronic kidney disease (9 patients with cardiorenal failure and 14 patients with end stage renal disease) and 19 healthy controls. Expression of P-selectin on the platelet surface measured as mean fluorescence intensity was significantly less in chronic kidney disease patients compared to controls after maximal stimulation with TRAP (9.7 (7.9-10.8) vs. 11.4 (9.2-12.2), P = 0.032), ADP (1.6 (1.2-2.1) vs. 2.6 (1.9-3.5), P = 0.002) and CRP (9.2 (8.5-10.8) vs. 11.5 (9.5-12.9), P = 0.004). Also the area under the curve was significantly different. There was no significant difference in half-maximal response between both groups.

Conclusion

In this study we found that patients with chronic kidney disease show reduced platelet reactivity in response of ADP, TRAP and CRP compared to controls. These results contribute to our understanding of the aberrant platelet function observed in patients with chronic kidney disease and emphasize the significance of using functional whole blood platelet activation assays.

Alteration of the platelet transcriptome in chronic kidney disease

Bleeding and thrombotic disorders are major complications affecting patients with chronic kidney disease (CKD). Exposure of circulating platelets to uraemic toxins and contact with artificial surfaces during dialysis induce platelet abnormalities and alter the platelet proteome. We hypothesised that these changes may be subsequent to changes in the composition and/or regulation of the platelet transcriptome. In this study, we investigated the circulating platelets of 10 CKD patients (i.e. five chronic haemodialysis patients and five stage 4 CKD uraemic patients) and five age- and sex-matched healthy subjects. We observed an alteration of the platelet messenger RNA (mRNA) and microRNA transcriptome in CKD patients. Impaired in uraemic platelets, the levels of some mRNAs and of most microRNAs appeared to be corrected by dialysis, which is consistent with a beneficial effect of dialysis and a mRNA regulatory role of platelet microRNAs. Reduced in platelets of uraemic patients, phosphatidylcholine transfer protein (PCTP) and WD repeat-containing protein 1 (WDR1) were found to be regulated by microRNAs, the latter of which involving hsa-miR-19b, a microRNA increased in platelets of uraemic patients and involved in platelet reactivity. These results suggest that an alteration of microRNA-based mRNA regulatory mechanisms may underlie the platelet response to uremia and entail the development of platelet-related complications in CKD.

Colorectal complications of end-stage renal failure and renal transplantation: a review

AIM

End-stage renal failure (ESRF) and renal transplant recipients are thought to be associated with an increased risk of colorectal complications.

METHOD

A review of the literature was performed to assess the prevalence and outcome in both benign and malignant colorectal disease.

RESULTS

No prospective randomized studies assessing colorectal complications in ESRF or renal transplant were identified. Case series and case reports have described the incidence and management of benign colorectal complications. Complications included diverticulitis,infective colitis, colonic bleeding and colonic perforation. There was insufficient evidence to associated iverticular disease with adult polycystic kidney disease.Three population-based studies have shown up to a twofold increased incidence of colonic cancer but not rectal cancer for renal transplant recipients. Bowel cancer screening (as per the general population) by faecal occult blood testing appears justified for renal transplant patients; however, evidence suggests that consideration of starting screening at a younger age may be worthwhile because of an increased risk of developing colonic cancer.Two population-based studies have shown a threefold and 10-fold increased incidence of anal cancer for renal transplant recipients. A single case–control study demonstrated significant increased prevalence of anal human papilloma virus (HPV) and intraepithelial neoplasia (AIN)in patients with established renal transplants.

CONCLUSIONS

Despite the lack of high-level evidence,ESRF and renal transplantation were associated with colorectal complications that could result in major morbidity and mortality. Bowel cancer screening in this patient group appears justified. The effectiveness of screening for HPV, AIN and anal cancer in renal transplant recipients remains unclear.

Retroperitoneal hemorrhage after endoscopic removal of a fish bone stuck in the duodenum of a patient receiving hemodialysis

Fish bones are often ingested accidently. Most of them passes out through the gastrointestinal tract safely, but serious complications, such as perforation, abscess, obstruction, and bleeding in the gastrointestinal tract, can occur. An ingested fish bone can be easily removed by endoscopy, and surgery is rarely required. However, there may be complications related to the endoscopic procedure including mucosal laceration, bleeding, fever, and perforation. Here, we report a case of retroperitoneal hemorrhage developed after endoscopic removal of a fish bone stuck in the duodenal wall, and then resolved spontaneously by conservative care.

Skin bleeding time for the evaluation of uremic platelet dysfunction and effect of dialysis

INTRODUCTION

In patients with chronic kidney disease (CKD) predisposition to bleeding is frequently seen due to disturbances in platelet adhesion and aggregation. Various tests have been utilized to evaluate the disturbance of hemostasis in end-stage renal disease patients. In this trial; we evaluated skin bleeding time in patients admitted to our hospital with uremic symptoms and having hemodialysis (HD) for the first time. We also examined the effects of HD and uremia on this test and investigated its effectiveness in predicting the hemorrhagic complications before implementation of invasive procedures in uremic patients.

MATERIAL-METHOD

Twenty nine patients (13 men,16 women; mean age 59.7 ± 18.1) with CKD who presented with symptoms of uremia and treated with HD for the first time were enrolled in this trial. The skin bleeding time were measured before initiation of first hemodialysis and after the second hemodialysis session.

RESULTS

The skin bleeding time after the second dialysis was significantly shorter when compared to pre-dialysis values (p < 0.05). Correlation analysis between the skin bleeding time and urea, creatinine, hemoglobin, platelet, and bicarbonate showed no correlation.

CONCLUSIONS

Skin bleeding time could reveal the uremic platelet dysfunction and beneficial effect of dialysis in the patients who presented with uremic symptoms and treated with HD for the first time. We suggest that skin bleeding time may be an appropriate test for the evaluation of hemostasis disturbance in uremic patients and prediction of the bleeding risk before invasive procedures.

Safety and efficacy of antiplatelet and antithrombotic therapy in acute coronary syndrome patients with chronic kidney disease

Chronic kidney disease (CKD) is prevalent and affects an ever-increasing proportion of patients presenting with acute coronary syndrome (ACS). Patients with CKD have a higher risk of ACS and significantly higher mortality, and are also predisposed to increased bleeding complications. Antiplatelet and antithrombotic drugs form the bedrock of management of patients with ACS. Most randomized trials of these drugs exclude patients with CKD, and current guidelines for management of these patients are largely based on these trials. We aim to review the safety and efficacy of these drugs in patients with CKD presenting with ACS.

Plasma concentration of von Willebrand factor predicts mortality in patients on chronic renal replacement therapy

BACKGROUND

Traditional cardiovascular risk factors do not explain the high incidence of cardiovascular mortality and morbidity in patients with end-stage renal disease. A prothrombotic state could accelerate the process of vascular disease in these patients.

METHODS

In this study, four platelet activation markers (NAP-2, P-selectin, GP1b and RANTES) and two endothelial cell activation markers (von Willebrand factor and its propeptide) were measured in 671 haemodialysis patients and 275 patients on continuous ambulatory peritoneal dialysis (PD). All were long-term dialysis patients. The risk of all-cause and cardiovascular mortality was assessed in relation to these markers after a mean follow-up time of 2.5 years.

RESULTS

The von Willebrand factor showed a positive correlation with total mortality in the haemodialysis patients. In an unadjusted model, the hazard rate (HR) of total mortality was 2.4 [95% confidence interval (95% CI) 1.7-3.4] in the upper quartile of von Willebrand factor compared with the lowest quartile. It remained statistically significant (HR 1.8; 95% CI 1.2-2.6) after adjustment for traditional risk factors. In contrast, no significant correlation was found between von Willebrand factor levels and total mortality in PD patients. Finally, no relationship between platelet activation markers and total mortality was found in either the haemodialysis or the PD patients.

CONCLUSION

It can be concluded that chronic endothelial cell activation, but not platelet activation, is related to all-cause mortality in end-stage renal disease patients on long-term dialysis.

Lower gastrointestinal bleeding in chronic hemodialysis patients

Gastrointestinal (GI) bleeding is more common in patients with chronic kidney disease and is associated with higher mortality than in the general population. Blood losses in this patient population can be quite severe at times and it is important to differentiate anemia of chronic diseases from anemia due to GI bleeding. We review the literature on common causes of lower gastrointestinal bleeding (LGI) in chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. We suggest an approach to diagnosis and management of this problem.

Risk factors for bleeding after endoscopic submucosal dissection of gastric epithelial neoplasm

BACKGROUND

Although endoscopic submucosal dissection (ESD) is standard therapy in Japan for gastric epithelial neoplasm, the complication rate is unsatisfactory, with postoperative bleeding as the major complication. The aim of the present study was to determine risk factors for post-ESD bleeding in patients with gastric epithelial neoplasm.

PATIENTS AND METHODS

The study included 764 patients in whom 924 gastric epithelial neoplasms were resected endoscopically between June 2005 and December 2009: the period during which preventative coagulation for all exposed vessels on the artificial ulcer with hemostatic forceps upon completion of ESD was performed routinely. We analyzed the risk factors for bleeding after ESD in relation to the various clinical factors.

RESULTS

The post-ESD bleeding rate was 3.0%. Dialysis (vs no dialysis, P = 0.034), operation time ≥75 min (vs <75 min, P = 0.012) and poor control of bleeding during ESD (vs good control, P = 0.014) were significantly related to post-ESD bleeding. Poor control of bleeding during ESD (vs good control; P = 0.04) and operation time ≥75 min (vs <75 min; P = 0.012) were significantly related to bleeding after second-look endoscopy.

CONCLUSIONS

Patients at high risk for post-ESD bleeding in gastric epithelial neoplasm were those undergoing dialysis, those in whom operation time was ≥75 min, and those in whom bleeding during ESD was poorly controlled. The latter two are risk factors for bleeding even after second-look endoscopy.

Clinical pharmacology basis of deriving dosing recommendations for dabigatran in patients with severe renal impairment

The objective of this work was to derive a dosing regimen for dabigatran in patients with severe renal impairment by modeling and simulation. Data from a dedicated renal impairment study were used to model the pharmacokinetics of dabigatran in normal and renal-impaired subjects. Model parameters were used to simulate the average concentration time-course of dabigatran following various dosing regimens. Pharmacokinetics of dabigatran in normal and renal-impaired subjects were best described by a 2-compartment open model with first-order absorption and elimination. Simulations were performed to select an appropriate regimen that reasonably matched the exposures on an average with those observed in subjects with moderate renal impairment who did not require a dose adjustment because of a favorable benefit-risk. Dabigatran 150 mg given once daily resulted in 35% higher average C(max, ss), whereas a 75 mg once daily regimen resulted in 42% lower average Cτ, relative to that observed with 150 mg administered twice daily in subjects with moderate renal impairment. A twice daily regimen of dabigatran 75 mg resulted in a reasonable matching of exposures and was selected as an appropriate dosing regimen in patients with severe renal impairment. This recommendation was incorporated in the dosing and recommendation section of dabigatran product insert.

Chronic renal failure is accompanied by endothelial activation and a large increase in microparticle numbers with reduced procoagulant capacity

BACKGROUND

In patients with chronic renal failure (CRF), cardiovascular disease is the leading cause of increased morbidity and mortality. We hypothesized a role for endothelial activation and microparticle (MP) numbers and procoagulant activity in the pre-thrombotic state of these patients.

METHODS

We analysed blood samples of 27 patients with CRF [8 chronic kidney disease Stage 4 (CKD4), 9 peritoneal dialysis (PD) and 10 haemodialysis (HD), samples taken before and after HD] and 10 controls. Degree and nature of endothelial activation were assessed by measuring mature von Willebrand factor (vWF) and vWF propeptide levels. Cellular MPs were characterized by flow cytometry and MP-specific thrombin generation (TG) measurements.

RESULTS

CRF was accompanied by chronic (CKD4 and PD) or acute (HD) endothelial activation. Patients with CRF had substantially higher MP numbers than controls (median 9400 versus 4350×10(6)/L, P=0.001), without significant differences between the treatment subgroups or between pre- and post-HD. The vast majority of MPs were platelet derived. Of the minor populations, endothelial MPs and tissue factor-bearing MPs were more abundant in CRF. MPs were procoagulant, but the increase in numbers was not reflected in a proportional increase in MP-specific TG.

CONCLUSION

Renal failure is accompanied by endothelial activation of a different nature in CKD4 and PD patients compared to HD patients, and results in all subgroups in an increase of mainly platelet-derived MPs that appear to be less procoagulant than in other disease states, possibly because of the uraemic functional defect of their cellular source.

Transient elastography to assess hepatic fibrosis in hemodialysis chronic hepatitis C patients

BACKGROUND AND OBJECTIVES

Although percutaneous liver biopsy (PLB) is the gold standard for staging hepatic fibrosis in hemodialysis patients with chronic hepatitis C (CHC) before renal transplantation or antiviral therapy, concerns exist about serious postbiopsy complications. Using transient elastography (TE, Fibroscan(®)) to predict the severity of hepatic fibrosis has not been prospectively evaluated in these patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 284 hemodialysis patients with CHC were enrolled. TE and aspartate aminotransferase-to-platelet ratio index (APRI) were performed before PLB. The severity of hepatic fibrosis was staged by METAVIR scores ranging from F0 to F4. Receiver operating characteristic curves were used to assess the diagnostic accuracy of TE and APRI, taking PLB as the reference standard.

RESULTS

The areas under curves of TE were higher than those of APRI in predicting patients with significant hepatic fibrosis (≥F2) (0.96 versus 0.84, P<0.001), those with advanced hepatic fibrosis (≥F3) (0.98 versus 0.93, P=0.04), and those with cirrhosis (F4) (0.99 versus 0.92, P=0.13). Choosing optimized liver stiffness measurements of 5.3, 8.3, and 9.2 kPa had high sensitivity (93-100%) and specificity (88-99%), and 87, 97, and 93% of the patients with a fibrosis stage of ≥F2, ≥F3, and F4 were correctly diagnosed without PLB, respectively.

CONCLUSIONS

TE is superior to APRI in assessing the severity of hepatic fibrosis and can substantially decrease the need of staging PLB in hemodialysis patients with CHC.

Intramural hematoma of duodenum: An unusual complication after endoscopic therapy for a bleeding peptic ulcer

Intramural hematoma of duodenum (IDH) is a relatively unusual complication associated with endoscopic treatment of bleeding peptic ulcer. This unusual condition is usually seen in children following blunt trauma to the abdomen. We describe here a case of IDH occurring following endoscopic therapy for bleeding duodenal ulcer in an adult patient with end-stage renal disease. The hematomas appeared on the second day of endoscopic intervention, caused transient duodenal obstruction and resolved spontaneously with conservative treatment in a week.

Endoscopic treatments of gastric mucosal lesions are not riskier in patients with chronic renal failure or liver cirrhosis

BACKGROUND

Little is known about the feasibility of endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) for patients with chronic renal failure (CRF) or liver cirrhosis (LC). This study aimed to assess the safety, efficacy, and clinical outcomes of EMR or ESD in patients with CRF or LC compared to those in patients without.

METHODS

Between February 2003 and November 2009, a total of 1016 gastric neoplastic lesions in 928 patients were treated by using EMR or ESD. Among them, 18 patients had LC and 17 patients had CRF. Their medical records were reviewed retrospectively. En bloc resection rate, histological complete resection rate, operation time, and complications were compared between patients with CRF or LC and those without (control group).

RESULTS

Baseline characteristics were not significantly different between the CRF, LC, and control groups except for a high rate of comorbidities in the CRF group and prolonged prothrombin time in the LC group. Operation time and therapeutic outcomes such as en bloc and complete resection rates did not differ significantly between the groups. Immediate bleeding tended to occur more frequently in the CRF+LC group than in controls (47.5 vs. 33.9%, p=0.077). There was no significant difference in the incidence of perforation between the CRF, LC, and control groups. The hospital stay was longer in the CRF+LC group than in the control group (6.4±3.53 vs. 4.9±3.15 days, p=0.012).

CONCLUSIONS

EMR and ESD for the treatment of early gastric neoplasia may be equally effective and tolerable in the CRF or the LC group compared to the control group, although patients with CRF or LC might need the longer admission period than the control group.

Aspirin is beneficial in hypertensive patients with chronic kidney disease: a post-hoc subgroup analysis of a randomized controlled trial

OBJECTIVES

The purpose of this study was to determine the benefit and risk associated with antiplatelet therapy in the chronic kidney disease (CKD) population.

BACKGROUND

Cardiovascular and possibly bleeding risks are elevated in patients with CKD. The balance of benefit and harm associated with antiplatelet therapy remains uncertain.

METHODS

The HOT (Hypertension Optimal Treatment) study randomly assigned participants with diastolic hypertension to aspirin (75 mg) or placebo. Study treatment effects were calculated using univariate proportional hazards regression models stratified by baseline estimated glomerular filtration rate (eGFR) with trends tested by adding interaction terms. End points included major cardiovascular events, total mortality, and major bleeding.

RESULTS

The study included 18,597 participants treated for 3.8 years. Baseline eGFR was < 60 ml/min/1.73 m(2) in 3,619 participants. Major cardiovascular events were reduced by 9% (95% confidence interval [CI]: -9% to 24%), 15% (95% CI: -17% to 39%), and 66% (95% CI: 33% to 83%) for patients with baseline eGFR of ≥ 60, 45 to 59, and < 45 ml/min/1.73 m(2), respectively (p trend = 0.03). Total mortality was reduced by 0% (95% CI: -20% to 17%), 11% (95% CI: -31% to 40%), and 49% (95% CI: 6% to 73%), respectively (p trend = 0.04). Major bleeding events were nonsignificantly greater with lower eGFR (hazard ratio [HR]: 1.52 [95% CI: 1.11 to 2.08], HR: 1.70 [95% CI: 0.74 to 3.88], and HR: 2.81 [95% CI: 0.92 to 8.84], respectively; p trend = 0.30). Among every 1,000 persons with eGFR < 45 ml/min/1.73 m(2) treated for 3.8 years, 76 major cardiovascular events and 54 all-cause deaths will be prevented while 27 excess major bleeds will occur.

CONCLUSIONS

Aspirin therapy produces greater absolute reduction in major cardiovascular events and mortality in hypertensive patients with CKD than with normal kidney function. An increased risk of major bleeding appears to be outweighed by the substantial benefits.

The ratio of aminotransferase to platelets is a useful index for predicting hepatic fibrosis in hemodialysis patients with chronic hepatitis C

Percutaneous liver biopsy is the gold standard for staging hepatic fibrosis of hemodialysis patients with chronic hepatitis C before renal transplantation or antiviral therapy. Concerns exist, however, about serious post-biopsy complications. To evaluate a more simple approach using standard laboratory tests to predict hepatic fibrosis and its evolution, we studied 279 consecutive hemodialysis patients with chronic hepatitis C and a baseline biopsy. Among them, 175 receiving antiviral therapy underwent follow-up biopsy to evaluate the histological evolution of fibrosis. Multivariate analysis of routine laboratory tests at baseline showed the aspartate aminotransferase-to-platelet ratio index was an independent predictor of significant hepatic fibrosis. The areas under curves of this ratio to predict fibrosis stages F2-4 were 0.83 and 0.71 in the baseline and follow-up sets; and 0.75 and 0.80 respectively, for patients with sustained or non-sustained virological response groups in the follow-up sets. By a judicious setting of cut-off levels for the baseline and non-sustained groups, and the sustained virological response group, almost half and 60 percent of the baseline and follow-up sets could be correctly diagnosed without biopsy. Our study found the aminotransferase-to-platelet ratio index is accurate and reproducible for assessing hepatic fibrosis in hemodialysis patients with chronic hepatitis C. Applying this simple index could decrease the need of percutaneous liver biopsy in this clinical setting.

[The role of platelets in atherosclerosis, diabetes mellitus, and chronic kidney disease. An attempt at explaining the TREAT study results]

Erythropoiesis-stimulating agents (ESA) are used to treat renal anemia. The TREAT study (Trial to Reduce Cardiovascular Events with Aranesp Ther- apy) of diabetic patients with chronic kidney disease (CKD) found that the risk of stroke was significantly higher than in the control arm. This raises the question as to what causes this phenomenon. Platelets may play a crucial role in this context. Atherogenesis involves complex interactions between platelets and monocytes (platelet-monocyte crosstalk) and with endothelial cells. Platelets are activated in cases of diabetes mellitus, especially. During atherogenesis, partial functions of platelets other than those inhibited by aspirin, as a cyclooxygenase inhibitor, or by adenosine diphosphate receptor P2Y(12)antagonists, such as thienopyridines, are of relevance. During platelet-monocyte crosstalk, specifically, an important role is played by adhesion receptors such as selectins and integrins. In addition, ESA cause platelet activation by direct and indirect mechanisms. Antagonistic thereto is a renal bleeding tendency in cases of severe CKD, due to platelet dysfunction, which can be remedied with appropriate renal replacement therapy and administration of ESA in order to reach a hemoglobin (Hb) level of 10 g/dl. However, if the Hb level exceeds 10 g/dl, the even stronger platelet activation caused by ESA, combined with the activation caused by diabetes, leads to a prothrombotic state, which in patients with severe atherosclerosis can result in acute atherothrombotic complications, in the genesis of which platelets play a key role. This would be one hypothesis for explaining the increased incidence of strokes in the TREAT study.