Unravelling the pathophysiology of chronic kidney disease-associated pruritus

Overlooked factor in the etiology of pruritus in hemodialysis patients: Ultrafiltration volume

INTRODUCTION

This study investigated the relationship between ultrafiltration (UF) volume and pruritus severity based on the idea that skin perfusion and inflammatory changes occur in dialysis patients with high UF volume.

MATERIALS AND METHODS

This observational study included 392 patients. Patients filled out the Numerical Rating Scale, Verbal Rating Scale, and Visual Analogue Scale, showing the severity of pruritis. UF volumes in the last 12 sessions were recorded and averaged.

RESULTS

The rate of patients with pruritis was between 59.4% and 67.5% in the three scales. In three pruritis scales, the severity of pruritis, age, body mass index (BMI), UF volume, and UF volume/body weight ratio were positively correlated. UF volume/body weight ratio, age, and BMI were independent predictors of pruritis severity.

CONCLUSION

Limiting interdialytic weight gain may be an important treatment approach in pruritus control.

Comparative efficacy of acupuncture point stimulation treatments for dialysis patients with uremic pruritus: a systematic review and network meta-analysis

Background

Uremic pruritus (UP) is a common complication of chronic kidney disease that causes sleep disturbances and increases all-cause mortality. Currently, the first-line medications for UP exhibit inadequate pruritus control with adverse effects. Various acupuncture point stimulation treatments (APSTs) have been shown to be effective as adjuvant therapies in UP, and a network meta-analysis can offer relative efficacy estimates for treatments for which head-to-head studies have not been performed.

Methods

We conducted a random-effects network meta-analysis on a consistency model to compare the different APSTs for UP. The primary outcomes were the mean visual analog scale (VAS) score and effectiveness rate (ER).

Results

The network meta-analysis retrieved 27 randomized controlled trials involving 1969 patients. Compared with conventional treatment alone, combination treatment with acupuncture (mean difference, -2.63; 95% confidence interval, -3.71 to -1.55) was the most effective intervention in decreasing VAS scores, followed by acupoint injection and massage (mean difference, -2.04; 95% confidence interval, -3.96 to -0.12). In terms of the ER, conventional treatment with acupuncture and hemoperfusion (risk ratio, 14.87; 95% confidence interval, 2.18 to 101.53) was superior to other therapeutic combinations. Considering the VAS score and ER, combination treatment with acupoint injection and massage showed benefits in treating UP.

Conclusion

Our network meta-analysis provided relative efficacy data for choosing the optimal adjuvant treatment for UP. Combined treatment with acupuncture was more effective than conventional treatment only and was the most promising intervention for treating UP.Systematic review registration: PROSPERO (CRD42023425739: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023425739).

Chronic kidney disease-associated pruritus: what is known and its application in children

Chronic kidney disease-associated pruritus (CKD-aP) or uremic pruritus (UP) is a frequent symptom in patients with kidney failure receiving kidney replacement therapy. Severe chronic kidney disease-associated pruritus correlates with poor outcome in patients on dialysis. It is multifactorial in etiology and has a significant impact on quality of life. There is, however, limited data for children. This review summarizes current epidemiology, clinical characteristics, pruritus scoring systems, and available therapeutic options for pruritus in patients with chronic kidney disease and those receiving dialysis. Optimal care requires proper awareness of the severity of symptoms, the impact on quality of life, and the possible long-term outcomes. Optimizing dialysis prescription and correcting electrolyte abnormalities are important treatment targets. A wide range of therapeutic options is also available although none are well-studied in children. An earlier recognition of this debilitating symptom in children and treatment is imperative. A higher resolution version of the Graphical abstract is available as Supplementary information.

A phase IV, randomised, double-blind, controlled, parallel group trial to evaluate the effectiveness and safety of Balneum Plus versus emollient in the treatment of chronic kidney disease-associated pruritus in haemodialysis patients

Background

Chronic kidney disease-associated pruritus (CKD-aP) is a common, distressing complaint in patients with advanced renal disease that is frequently overlooked. Treatment is often unsatisfactory. Balneum Plus (Almirall, Barcelona, Spain) is a cream containing 3% lauromacrogols and 5% urea, commonly used to treat atopic dermatitis. It has not been studied in CKD-aP to date.

Methods

Adult haemodialysis patients were randomised 1:1 to apply Balneum Plus or E45 (Reckitt Beckiser, Slough, UK) to compare the active ingredients of lauromacrogol and urea with a control cream. Itch was defined as three episodes of itching during the last 2 weeks, appearing a few times a day, lasting a few minutes and troubling the patient [1]. Patients with other causes of itch, e.g. eczema and liver disease, were excluded. The primary outcome was a reduction in itch as measured by the visual analogue scale (VAS) score at 4 weeks and analysed using an analysis of covariance approach.

Results

A total of 314 patients were screened and 58 patients were randomised, 29 in each group. Three patients dropped out in each group. The median baseline VAS scores were 6.5 [interquartile range (IQR) 4.4-8.0] in the Balneum Plus group and 6.3 (IQR 5.1-7.3) in the E45 group. After 4 weeks, VAS scores decreased to 2.6 (IQR 0.9-4.5) and 2.0 (IQR 0.5-4.8) in the Balneum Plus and E45 groups respectively (P = 0.64 for the difference). Using a validated questionnaire to assess secondary outcomes, we found that the Balneum Plus group had longer itching episodes, more difficulty staying asleep and itching was more annoying than in the E45 group. There was no significant difference in adverse events between the two groups. One patient reported inflamed spots on the abdominal skin in the Balneum Plus group.

Conclusion

This is the first randomised controlled study of two different emollients for the treatment of CKD-aP and is a negative study. We found no significant difference in itch scores between Balneum Plus and E45.

Chronic Kidney Disease-Associated Pruritus and Quality of Life: Learning from Our Patients

Chronic kidney disease-associated pruritus is itching directly related to kidney disease that cannot be explained by any other condition. Despite technological advances in the different aspects of dialysis sessions and the best treatment for chronic kidney disease patients, it is still a common problem in our patients. The many complex physiological mechanisms involved, the different hypotheses made over the years on the aetiology of the condition, and the great clinical variability may partially explain the limited knowledge about this problem and the difficulties in treating it. The presence of all these factors leads to the persistence of unpleasant symptoms, which must affect the disease burden and quality of life of kidney patients. Through the presentation of an illustrative clinical case, the aim of this review article is to highlight the need for adequate diagnosis and an improved approach to all aspects of chronic kidney disease-associated pruritus, in view of the heavy burden of the disease and the huge impact on the patient's quality of life.

Moderate-to-severe pruritus in untreated or non-responsive hemodialysis patients: results of the French prospective multicenter observational study Pruripreva

BACKGROUND

Chronic kidney disease-associated pruritus (CKD-aP) is a common condition in patients treated with hemodialysis, and has a negative impact on quality of life (QoL). Due to the lack of standardized diagnostic tools and frequent underreporting, pruritus prevalence remains poorly documented.

METHODS

Pruripreva was a prospective multicenter observational study that aimed to evaluate the prevalence of moderate to severe pruritus in a cohort of French hemodialysis patients. The primary endpoint was the rate of patients with mean Worst Itch Numerical Rating Scale (WI-NRS) score ≥4 calculated over 7 days (moderate pruritus, 4-6; severe, 7-8; very severe, 9-10). Impact of CKD-aP on QoL was analyzed according to its severity (WI-NRS), using 5-D Itch scale, EQ-5D and Short Form (SF)-12.

RESULTS

Mean WI-NRS was ≥4 in 306 patients (mean age, 66.6 years; male, 57.6%) out of 1304 and prevalence of moderate to very severe pruritus was 23.5% (95% confidence interval 21.2-25.9). Pruritus was unknown prior to the systematic screening in 37.6% of patients, and 56.4% of those affected were treated for this condition. The more severe the pruritus, the poorer the QoL according to the 5-D Itch scale, EQ-5D and SF-12.

CONCLUSION

Moderate to very severe pruritus was reported in 23.5% of hemodialysis patients. CKD-aP was underrated although it is associated with a negative impact on QoL. These data confirm that pruritus in this setting is an underdiagnosed and underreported condition. There is an urgent demand for new therapies to treat chronic pruritus associated with CKD in hemodialysis patients.

The effectiveness of sertraline in alleviating uremic pruritus in hemodialysis patients: a randomized clinical trial

INTRODUCTION

Uremic pruritus (UP) is a common and distressing symptom in end stage renal disease (ESRD) patients. Many approaches have been tested to improve UP without a clear success. We aimed to assess the effect of sertraline on UP in hemodialysis (HD) patients.

METHODS

This research is a double-blinded, placebo-controlled, multicentric randomized clinical trial which included sixty patients maintained on regular HD. Patients were allocated to receive sertraline 50 mg twice daily or placebo for 8 weeks. The Visual analogue scale (VAS) and the 5-D itch scale were used to assess pruritus before and after the course of treatment.

RESULTS

At study end in sertraline group, there was a significant decrease from baseline findings in the VAS score (p < 0.001), and the 5-D itch scale (p < 0.001). On the other hand, in placebo group the VAS score showed a slight non-significant decrease (p = 0.469), and the 5-D scale (p = 0.584) increased from baseline measurements. The percentage of patients with severe and very severe pruritus decreased significantly in the sertraline group in both scores [(VAS score: p = 0.004), (5-D itch score: p = 0.002)] with no significant change in the placebo group [(VAS score: p = 0.739), (5-D itch scale: p = 0.763)]. There was a significant positive relation between the VAS and 5-D itch scores and serum urea with p value of 0.002 and 0.001 respectively, and serum ferritin with p value of < 0.001 with both.

CONCLUSIONS

Patients treated with sertraline had a significant improvement in pruritus as compared with those who received placebo suggesting a potential role for sertraline to treat uremic pruritus in HD patients. Larger randomized clinical trials are needed to confirm these findings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05341843. First registration date: 22/04/2022.

Endogenous Opioid Imbalance as a Potential Factor Involved in the Pathogenesis of Chronic Kidney Disease-Associated Pruritus in Dialysis Patients

Chronic pruritus is one of the most common symptoms of dermatological diseases. It may occur in the course of other disorders, such as kidney disease. Chronic kidney disease-associated pruritus (CKD-aP) most often affects people with end-stage renal disease. The etiology of this condition is still not fully understood, but researchers are currently focusing on a thorough analysis of the association between disturbed opioid balance and increased neuronal signaling leading to pruritus. The aim of this study is to assess the concentration of endogenous opioids in dialysis patients with and without pruritus and in the control group, and to determine the correlation between the concentration of these substances and the occurrence and severity of itching. The study involved 126 dialysis patients and 50 healthy controls. Patients were divided into groups with pruritus (n = 62) and without pruritus (n = 64). The severity of pruritus was assessed using the NRS scale. The concentration of endogenous opioids was determined using the ELISA. The concentration of met-enkephalin was higher in the group of patients with pruritus compared to the control group. Moreover, significantly lower levels of β-endorphin and dynorphin A were observed in the group of dialysis patients compared to the control group. In addition, a statistically significant difference was seen between the β-endorphin concentration in the group of dialysis patients with pruritus compared to the group without pruritus. The ratio of β-endorphin/dynorphin A concentrations was significantly lower in the group of patients with pruritus compared to patients without pruritus and the control group. No correlations were found between serum level of studied opioids and the severity of pruritus. The concentrations of the studied opioids did not correlate with the severity of pruritus. Observed opioid imbalance may affect the occurrence of CKD-aP in dialysis patients, but a thorough understanding of the mechanism of action of these substances in the sensation of pruritus is necessary to assess the possibility of finding a new therapeutic target.

Phase 2 Trial of Difelikefalin in Notalgia Paresthetica

BACKGROUND

Notalgia paresthetica is a neuropathic disorder characterized by pruritus in a circumscribed region of the upper back. Difelikefalin, a selective kappa opioid receptor agonist, has shown efficacy in other chronic pruritic conditions and is being investigated for the treatment of notalgia paresthetica.

METHODS

In this phase 2, double-blind, placebo-controlled trial, we randomly assigned, in a 1:1 ratio, patients with moderate-to-severe pruritus caused by notalgia paresthetica to receive 2 mg of oral difelikefalin or placebo twice daily for 8 weeks. The primary outcome was the change from baseline at week 8 in the weekly mean score on the daily Worst Itch Numeric Rating Scale (WI-NRS; scores range from 0 [no itch] to 10 [worst itch imaginable]). The secondary clinical outcomes were itch-related quality-of-life and itch-related sleep measures.

RESULTS

A total of 126 patients were enrolled; 62 patients were assigned to receive difelikefalin, and 63 were assigned to receive placebo. One patient who had been assigned to receive difelikefalin withdrew consent before the first dose and is not included in the main analyses. The mean baseline WI-NRS score was 7.6 (indicating severe itch) in each group. The change from baseline in the weekly mean WI-NRS score at week 8 was -4.0 points in the difelikefalin group and -2.4 points in the placebo group (difference in change, -1.6 points; 95% confidence interval, -2.6 to -0.6; P = 0.001). The results for the secondary outcomes generally did not support those of the primary analysis. Headache, dizziness, constipation, and increased urine output occurred more frequently in the difelikefalin group than in the placebo group.

CONCLUSIONS

Among patients with notalgia paresthetica, oral treatment with difelikefalin resulted in modestly greater reductions in itch intensity scores than placebo over a period of 8 weeks but was associated with adverse events. Larger and longer trials are needed to assess the efficacy and safety of difelikefalin treatment in this disorder. (Funded by Cara Therapeutics; KOMFORT ClinicalTrials.gov number, NCT04706975.).

Pathogenesis and Treatment of Pruritus Associated with Chronic Kidney Disease and Cholestasis

Itching is an unpleasant sensation that provokes the desire to scratch. In general, itching is caused by dermatologic diseases, but it can also be caused by systemic diseases. Since itching hampers patients' quality of life, it is important to understand the appropriate treatment and pathophysiology of pruritus caused by systemic diseases to improve the quality of life. Mechanisms are being studied through animal or human studies, and various treatments are being tested through clinical trials. We report current trends of two major systemic diseases: chronic kidney disease and cholestatic liver disease. This review summarizes the causes and pathophysiology of systemic diseases with pruritus and appropriate treatments. This article will contribute to patients' quality of life. Further research will help understand the mechanisms and develop new strategies in the future.

Etiopathogenesis of chronic kidney disease-associated pruritus: putting the pieces of the puzzle together

Defined as the unpleasant sensation that causes the desire to scratch, pruritus is the most common skin symptom associated with uremia and appears in almost half of patients with advanced chronic kidney disease (CKD). Beyond its direct impact on quality of life, CKD-associated pruritus (CKD-aP) is an independent predictor of mortality that also has a synergistic effect with other quality of life-related symptoms, such as insomnia, depression, and anxiety. Although different mechanisms have been proposed to explain the origin of Pa-ERC, its etiopathogenesis is still not fully understood. Since new therapeutic targets have been identified and several clinical trials have recently shown promising results, our current understanding of the interrelationships has expanded significantly and the pathophysiological mechanisms underlying CKD-aP are now considered to be multifactorial. The potential triggers of pruritus in patients with CKD are discussed in this review, including hypotheses about skin xerosis, accumulation of uremic toxins, dysregulation of the immune system and systemic inflammation, uremic neuropathy, and imbalances in the endogenous opioid system. Other non-uremic causes of pruritus are also discussed, with the aim of guiding the physicians to apply an adequate aetiopathogenic approach to CKD-aP in their day-to-day clinical practice.

Clinical Efficacy and Safety of Chinese Herbal Medicine in the Treatment of Uremic Pruritus: A Meta-Analysis of Randomized Controlled Trials

Uremic pruritus is a disturbing and refractory symptom in patients with advanced chronic kidney disease. Chinese herbal medicine has been reported to alleviate uremic pruritus. To investigate the effects of Chinese herbal medicine, we conducted a systematic review and meta-analysis on patients with uremic pruritus. We searched databases (prior to 3 May 2022) for randomized controlled trials on the effects of Chinese herbal medicine in treating uremic pruritus. Our meta-analysis included 3311 patients from 50 randomized controlled trials. In patients with uremic pruritus, adjunctive Chinese herbal medicine significantly improved overall effectiveness (risk ratio 1.29, 95% CI 1.23 to 1.35), quality of life, renal function, reduced pruritus score, and inflammatory biomarkers compared to control groups with hemodialysis alone or with anti-pruritic treatments. Chinese herbal medicine treatment showed a time-dependent tendency in improving the visual analog scale of dialysis patients. Compared to control groups, no significantly higher risk of adverse events in patients taking Chinese herbal medicine (risk ratio 0.60, 95% CI 0.22 to 1.63). Chinese herbal medicine appears to be effective and safe in complementing the treatment of patients with uremic pruritus.

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.

Pruritus in Chronic Kidney Disease: An Update

Chronic kidney disease-associated pruritus (CKDaP) is an often under-diagnosed and under-recognized condition, despite its considerable prevalence within the chronic kidney disease (CKD) population. Universally accepted guidelines are also lacking. The true prevalence of CKDaP worldwide therefore remains unknown, although its negative impact on mortality and health-related quality of life outcomes is very clear. The pathophysiological mechanisms leading to the onset of CKDaP are only partly understood. CKDaP is currently believed to be caused by a multifactorial process, from local skin changes, metabolic alterations, the development of neuropathy and dysregulation of opioid pathways, and psychological factors. Much work has been carried out towards a more systematic and structured approach to clinical diagnosis. Various tools are now available to assess the severity of CKDaP. Many of these tools require greater validation before they can be incorporated into the guidelines and into routine clinical practice. Further efforts are also needed in order to increase the awareness of clinicians and patients so that they can identify the CKDaP signs and symptoms in a timely manner. Currently established treatment options for CKDaP focus on the prevention of xerosis via topical emollients, the optimization of dialysis management, early referral to kidney transplantation if appropriate, oral antihistamine, and a variety of neuropathic agents. Other novel treatment options include the following: topical analgesics, topical tacrolimus, cannabinoid-containing compounds, antidepressants, oral leukotrienes, opioids, and non-pharmacological alternative therapies (i.e., phototherapy, dietary supplements, acupuncture/acupressure). We provide an updated review on the evidence relating to the epidemiology, the pathophysiology, the clinical assessment and diagnosis, and the management of CKDaP.

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.