Uremic pruritus and long-term morbidities in the dialysis population

Pruritus and protein-bound uremic toxins in patients undergoing hemodialysis: a cross-sectional study

Background

Patients undergoing hemodialysis frequently experience pruritus; its severity is associated with poor quality of life and mortality. Recent progress in hemodialysis treatment has improved the removal of small- and middle-molecular-weight molecules; however, the removal of protein-bound uremic toxins (PBUTs) remains difficult. It is possible that pruritus is associated with serum PBUTs in patients undergoing hemodialysis.

Methods

We conducted a multicenter cross-sectional study in patients undergoing hemodialysis (n = 135). The severity of pruritus was assessed using the 5D-itch scale and medication use. Serum PBUTs, including indoxyl sulfate, p-cresyl sulfate, indole acetic acid, phenyl sulfate, and hippuric acid, were measured using mass spectrometry; the PBUT score was calculated from these toxins using principal component analysis. Univariate and multiple regression analyses were performed to examine independent predictors of pruritus.

Results

Pruritus was reported by 62.2%, 21.5%, and 13.3%, 1.5% and 0.7% as 5 (not at all), 6-10, 11-15, 16-20, and 21-25 points, respectively. The PBUT score was higher in patients undergoing dialysis having pruritus than those without pruritus (0.201 [-0.021 to 0.424] vs -0.120 [-0.326 to 0.087]; P = 0.046). The PBUT score was shown to have an association with the presence of pruritus (coefficient 0.498[Formula: see text]0.225, odds ratio: 1.65 [1.06-2.56]; P = 0.027).

Conclusion

Uremic pruritus was frequently found and associated with the PBUT score in patients undergoing hemodialysis. Further studies are required to clarify the impact of PBUTs on uremic pruritus and to explore therapeutic strategies in patients undergoing hemodialysis.

Pharmacokinetics, Metabolism, and Excretion of Intravenous [14C]Difelikefalin in Healthy Subjects and Subjects on Hemodialysis

BACKGROUND AND OBJECTIVE

Difelikefalin, a selective kappa-opioid receptor agonist, is the first approved treatment for moderate-to-severe pruritus in patients with end-stage renal disease (ESRD) on hemodialysis (HD) in the USA and Europe. The purpose of this open-label study was to investigate the pharmacokinetics and disposition of [14C]difelikefalin following a single intravenous dose in subjects with normal renal function and subjects on HD.

METHODS

Twelve adult males (n = 6 healthy subjects; n = 6 subjects on HD) received single intravenous doses of [14C]difelikefalin containing 100 µCi (total doses of 1.7-3.0 μg/kg difelikefalin). Blood, urine, feces, and dialysate samples (when applicable) were collected after dosing.

RESULTS

The median time to maximum concentration was similar for HD and healthy subjects, occurring at 5 min post-dose. The mean area under the concentration-time curve (AUC) was approximately 11-fold higher in HD versus healthy subjects; mean plasma half-life was 38.0 h and 2.6 h, respectively. In healthy subjects, 80.5% of the dose was recovered in urine, and 11.3% was recovered in feces. In subjects on HD, 58.8% of the dose was recovered in feces, and 19.5% was recovered in dialysate [for subjects on HD with residual kidney function (n = 3), 11.2% was recovered in urine]. Based on plasma AUClast, parent [14C]difelikefalin was the most abundant analyte in systemic circulation (> 99% of total exposure) for both cohorts. Metabolite profiles in urine and feces suggested minimal metabolism of the parent compound.

CONCLUSION

In subjects on HD, difelikefalin total exposure was higher and plasma half-life was longer compared with subjects with intact renal function. Metabolism was low in both healthy subjects and subjects on HD, with unchanged drug representing > 99% of systemic circulation; however, the route of excretion was primarily into urine versus feces in healthy subjects, and feces versus dialysate in subjects on HD.

REGISTRATION

ClinicalTrials.gov NCT03947970.

Perception of Spanish nephrologists on an old unsolved problem: Pruritus associated with chronic kidney disease (CKD-aP)

INTRODUCTION

Pruritus associated with chronic kidney disease is defined as the sensation of itching, in people with chronic kidney disease, in a one area or all over the body that causes the need to scratch, after having ruled out other dermatological or systemic causes. It is an old and known problem whose prevalence has been able to decrease with the improvement of dialytic techniques but which still persists and is underdiagnosed.

OBJECTIVES

The objective of this study was to analyse the current perception of nephrologists about this problem that influences the quality of life of people with chronic kidney disease through a survey.

RESULTS

135 nephrologists, most of them engaged in haemodialysis, participated. 86% considered that pruritus associated with chronic kidney disease is still a problem today that affects the quality of life. Most nephrologists believe that the main pathophysiological cause is uremic toxins (60%) and only 16% believe that it is due to the dysregulation of the opioid system/endorphins-dynorphins. Only 16% comment that the prevalence of pruritus in their centre is greater than 20%. 40% believe that the diagnosis is made because it is manifested by the patient and only 27% because it is asked by the doctor. Moreover, it is not usual to use scales to measure it or the codification in the medical records. The main treatment used is antihistamines (96%), followed by moisturizers/anaesthetics (93%) and modification of the dialysis regimen (70%).

CONCLUSIONS

Pruritus associated with chronic kidney disease is still a current problem, it is underdiagnosed, not codified and with a lack of indicated, effective and safe treatments. Nephrologists do not know its real prevalence and the different pathophysiological mechanisms involved in its development. Many therapeutic options are used with very variable results, ignoring their efficacy and applicability at the present time. The new emerging kappa-opioid-receptor agonist agents offer us an opportunity to reevaluate this age-old problem and improve the quality of life for our patients with chronic kidney disease.

Pruritus in chronic kidney disease

PURPOSE OF REVIEW

Among the many difficult symptoms that patients with kidney disease experience, pruritus is one of the most frequent and troubling. Because a substantial amount of new information has accumulated, we seek here to review the subject.

RECENT FINDINGS

Pruritus is not only a common problematic symptom among patients with kidney disease, but its considerably more frequent than nephrologists recognize. The result for patients is not just uncomfortable itch but degraded quality of life as well. The pathogenesis is increasingly understood, but many aspects remain to be fully resolved. Importantly, research is progressing on treatment, leading to the first approved medication in the United States, difelikefalin, in August, 2021.

SUMMARY

As nephrology is progressing to a greater focus on patient symptoms, recognition of the importance of pruritus has led to increased interest and improved diagnosis and treatment options.

Patent Highlights February-March 2022

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.

Uremic Pruritus: From Diagnosis to Treatment

Uremic pruritus, or chronic kidney disease-associated pruritus, is common, bothersome, and sometimes debilitating in patients with chronic kidney disease or end-stage renal disease. Due to its variable clinical manifestations, the diagnosis of uremic pruritus requires exquisite evaluation. Excluding itch resulting from other dermatological causes as well as other systemic conditions is essential for a proper diagnosis. The pathophysiology of uremic pruritus remains uncertain. Hypotheses including toxin deposition, immune system dysregulation, peripheral neuropathy, and opioid imbalance are supposed. This review summarizes the way to accurately diagnose uremic pruritus and describes the latest treatment options.

Itching in dialysis patients: impact on health-related quality of life and interactions with sleep problems and psychological symptoms – results from the RENINE/PROMs registry

Background

Itching (pruritus) is common in dialysis patients, but little is known about its impact on health-related quality of life (HRQOL), sleep problems and psychological symptoms. This study investigates the impact of itching in dialysis patients by looking into the persistence of itching, the effect of itching on the course of HRQOL and the combined effect of itching with sleep problems and with psychological symptoms on HRQOL.

Methods

Data were obtained from the RENINE/PROMs registry and included 2978 dialysis patients who completed patient-reported outcome measures between 2018 and 2020. Itching, sleep problems and psychological symptoms were assessed with the Dialysis Symptom Index (DSI) and HRQOL with the 12-item Short Form Health Survey. Effects of itching on HRQOL and interactions with sleep problems and psychological symptoms were investigated cross-sectionally and longitudinally using linear regression and linear mixed models.

Results

Half of the patients experienced itching and in 70% of them, itching was persistent. Itching was associated with a lower physical and mental HRQOL {−3.35 [95% confidence interval (CI) −4.12 to −2.59) and −3.79 [95% CI −4.56 to −3.03]}. HRQOL remained stable during 2 years and trajectories did not differ between patients with or without itching. Sleep problems (70% versus 52%) and psychological symptoms (36% versus 19%) were more common in patients with itching. These symptoms had an additional negative effect on HRQOL but did not interact with itching.

Conclusions

The persistence of itching, its impact on HRQOL over time and the additional effect on HRQOL of sleep problems and psychological symptoms emphasize the need for recognition and effective treatment of itching to reduce symptom burden and improve HRQOL.

Chronic Kidney Disease-Associated Pruritus: A Glance at Novel and Lesser-Known Treatments

Chronic kidney disease-associated pruritus (CKD-aP), also known as uremic pruritus, has been associated with increased mortality and lower quality of life among patients with chronic kidney disease (CKD). The relentless nature of the condition is mainly due to its diverse and complex etiologies, which are still being studied. Despite the introduction of many agents to treat it, the resolution rates of CKD-aP still remain unsatisfactory. This study sought to review the lesser-known/novel treatments and establish a relationship between their mechanism of action and the proposed etiologies implicated in CKD-aP. We also discuss the role of dialysis modification in managing CKD-aP.

A decent proportion of the reviewed studies have proposed that the agents analyzed in them act through hampering inflammation. Interestingly, the results of two agents alluded to the role of dysbiosis in CKD-aP. The addition of hemoperfusion to the dialysis regimen of patients with CKD-aP improved the severity of their symptoms.

The featured treatments could be tried in patients with intractable symptoms. However, additional research is needed to confirm the findings reported in these studies. A better understanding of the pathologic mechanisms is required to help guide the development of agents that can better treat CKD-aP.

Epidemiology and burden of chronic kidney disease-associated pruritus

Chronic kidney disease–associated pruritus (CKD-aP) is a common, yet underrecognized condition in patients with CKD and end-stage kidney disease (ESKD). Real-world observational studies indicate that CKD-aP affects up to 80% of ESKD patients undergoing haemodialysis (HD), with ∼40% experiencing moderate to severe itch. CKD-aP can negatively impact patients’ mental and physical health-related quality of life (HRQoL) and is also associated with sleep disturbance and depression. Several studies have found that CKD-aP is a predictor of adverse medical outcomes, including an increased risk of hospitalizations and mortality. In this article we review the literature relating to the epidemiology of CKD-aP to describe its prevalence across the treatment spectrum of CKD (non-dialysis, HD, peritoneal dialysis and transplant recipients) and to summarize potential risk factors associated with its development. We also review key data from studies that have evaluated the impact of CKD-aP on HRQoL and medical outcomes.

The clinical effectiveness and safety of traditional Chinese medicine uremic clearance granule combined with high-flux hemodialysis in the treatment of uremic pruritus: A protocol for systematic review and meta analysis

BACKGROUND

Skin pruritus is a common complication in patients with uremia. When the hemodialysis time of patients is extended, and the probability of skin pruritus is greater. Patients often have the symptoms of skin pruritus intolerable, affecting the normal sleep and normal life of patients. The patients with uremic pruritus often constant scratching and pruritus skin, resulting in broken skin, and further symptoms such as infection, and subsequent skin shedding, prurigo nodularis, and other adverse complications, aggravating the patient's condition. Some patients will experience symptoms such as depression and insomnia due to skin pruritus, and simply scratching the skin lead to infection. Severely affected patients may even show suicidal tendency, endangering the physical and mental health of patients, and it is needed to give the effective treatment to patients. Hemodialysis is a common treatment for uremic pruritus, which can effectively relieve the pruritus symptoms of patients. The drugs can also relieve the symptoms and improve the degree of pruritus in patients. And some studies show that traditional Chinese medicine UCG combined with HFH in the treatment of uremic pruritus has a very good effect, Therefore, this study will systematically evaluate the clinical efficacy and safety of UCG combined with HFH and HFH alone in the treatment of uremic pruritus.

METHODS

Use computer to search English and Chinese databases, English databases include: PubMed, Web of Science, EMbase, The Cochrane Library. Chinese databases include: CNKI, CBM, WanFang Data and VIP databases, collecting the RCT on the clinical effectiveness and safety of UCG combined with HFH and HFH alone in the treatment of uremic pruritus. The retrieval time is from the beginning of each database to May 1, 2021. In order to improve the retrieval rate of the literature, the references cited in the included research are also collected and screened. Set Chinese and English as the search language. Two members of the research group independently collected, included and excluded the literatures. In case of disagreement, consulting the third party to assist in the judgment. For the literature with missing data, the original author should be contacted as far as possible to obtain complete data. Two evaluators evaluate the bias risk of included studies according to the Cochrane Handbook bias risk assessment tool for RCT. RevMan 5.3 software is used for statistical analysis and the forest plot is drawn to show the outcome indicators and funnel plot is drawn to show the publication bias.

RESULTS

This study evaluates the advantages and disadvantages of traditional Chinese medicine UCG combined with HFH and HFH alone in the treatment of uremic pruritus through the clinical effectiveness and safety-related indicators.

CONCLUSION

This study will give a positive conclusion on the efficacy and safety of uremic clearance granule in the treatment of uremic pruritus, and the research results will be published in professional journals in the form of academic papers, thus benefiting more patients.

ETHICS AND DISSEMINATION

This study belongs to meta-analysis and all data comes from academic papers published publicly in formal academic journals, so there are no ethical issues involved in this study and no ethical review or approval is required.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/W8P5G.

Mucocutaneous manifestations of patients with chronic kidney disease under hemodialysis: A cross-sectional study of 49 patients

Chronic kidney disease (CKD) is a common medical problem with well-known dermatologic manifestations, some of which highly disturb the patients' quality of life. This cross-sectional study was designed to identify the prevalence and type of cutaneous involvement in CKD patients. The skin manifestations of 49 patients with CKD undergoing hemodialysis at Akhavan Hospital in Kashan, Iran, were recorded over 2 months. Diabetes (35%) was the most common cause of chronic renal failure in the patients, and the most common skin manifestations were xerosis (95.9%), uremic pigmentation (89.8%), scleral discoloration (87.8%), dental discoloration (85.2% among the patients with natural teeth), dry mouth (65.3%), varicosity (61.2%), pruritus (57.1%), skin atrophy (49%), lentigo (46.9%), subungual hyperkeratosis (42.9%), half and half nail dystrophy (34.7%), and purpura (26.5%). Mucocutaneous involvement has a very high prevalence in CKD patients undergoing hemodialysis, and some of the cases are medically and cosmetically disturbing; therefore, with better knowledge about the type and prevalence of these involvements, the consequences can be better predicted and managed. Further studies are recommended to be conducted on the association between these signs and CKD grade, and clinical trials are also required for establishing the treatment options available for these signs and then assessing the patients' quality of life as a primary outcome measure.