Pruritus as a Patient-Reported Primary Trial End Point in Hemodialysis: Evaluation and Implications

Impact of Difelikefalin on the Health-Related Quality of Life of Haemodialysis Patients with Moderate-To-Severe Chronic Kidney Disease-Associated Pruritus: A Single-Arm Intervention Trial

OBJECTIVE

Chronic kidney disease-associated pruritus (CKD-aP) can have a substantial negative impact on health-related quality of life (HRQoL), including an increased risk of depression, anxiety and sleep disturbance. This trial aimed to assess the impact of intravenous difelikefalin on HRQoL in haemodialysis patients with moderate-to-severe CKD-aP.

METHODS

Post hoc analysis of an open-label, multicentre, single-arm intervention trial assessed pruritus severity and HRQoL at baseline and at 12 weeks of difelikefalin treatment using Worst Itching Intensity Numerical Rating Scale (WI-NRS), Sleep Quality Numeric Rating Scale (SQ-NRS), 5-D itch scale, Skindex-10 scale, EQ-5D-5L with Pruritus Bolt-On (EQ-PSO).

RESULTS

A total of 222 patients received ≥ 1 dose of difelikefalin, and 197 patients completed 12 weeks of difelikefalin treatment. Clinically meaningful changes from baseline to 12 weeks were observed in all disease-specific measures: 73.7% of patients achieved a ≥ 3-point reduction in the weekly mean of 24 h WI-NRS scores and 66% of patients experienced ≥ 3-point improvements in SQ-NRS scores. Improvements were also observed in all Skindex-10 scale and 5-D itch scale domain scores. The percentage of patients reporting no problems in all EQ-PSO domains increased from 1.4 to 24.7% (p < 0.001), respectively. Patients' generic HRQoL EQ-5D-5L mean utility and EQ-5D visual analogue scale scores increased from baseline to 12 weeks: mean changes 0.04 (p = 0.001) and 2.8 (p = 0.046), respectively.

CONCLUSIONS

Patients undergoing haemodialysis with moderate-to-severe CKD-aP receiving difelikefalin reported experiencing clinically meaningful improvements in both their pruritus symptoms and itch-related QoL.

CLINICALTRIALS

gov registration number, NCT03998163; first submitted, 7 May 2019.

The Burden of Pruritus Associated With CKD: A Mixed Methods Analysis Among Patients Undergoing Dialysis

Rationale & Objective

Despite its prevalence and distress to patients, chronic kidney disease-associated pruritus (CKD-aP) is poorly characterized, which may contribute to the condition's underdiagnosis and inadequate management. This study aimed to understand the symptom experience of patients with CKD-aP and the extent to which pruritus impacts their lives.

Study Design

Mixed methods study including one-on-one qualitative interviews and completion of the Skindex-10 Questionnaire (measuring itch-related quality of life).

Setting & Participants

A total of 23 patients undergoing hemodialysis and reporting pruritus at 4 dialysis centers in the United States.

Analytical Approach

Interviews followed a semistructured guide that included targeted and follow-up questions to elicit discussion of patients' symptoms of pruritus, including frequency and variability, impact on activities of daily living, and emotional and social functioning. Interviews were digitally audio-recorded. A coding dictionary was developed from transcripts to analyze themes and concepts.

Results

Participants described their itch with various terms, including "numbness," "pain," and "tingling" on their skin. Itch affected multiple areas but especially the back, usually occurred daily, and was often worse at night. For some, itching was a constant experience. Patients relieved their itch through scratching and various off-label treatments; some reported skin damage from excessive scratching and most indicated treatments provided limited relief. Pruritus considerably disrupted physical function, including sleep, daily activities, social functioning and relationships, and emotional and psychological wellbeing. All participants reported being bothered by their itching during the past week on the Skindex-10 Questionnaire.

Limitations

All participants were from the United States, so the findings may not be generalizable to other countries.

Conclusions

Although symptom experience varies considerably, CKD-aP causes severe distress for many patients undergoing hemodialysis and can profoundly impair their quality of life. The results of this study show the impact of itch from patients' perspectives and highlight the need for greater awareness and better management of this condition.

Plain-Language Summary

Patients with chronic kidney disease often experience itching, or pruritus, but its importance to patients is regularly overlooked. This study used one-on-one interviews to investigate patients' experiences of chronic kidney disease-associated pruritus and how it impacts their lives. We found that participants experienced itch on various body areas and used different words to describe their itch (eg, "numbness" and "pain"). Some reported skin damage from excessive scratching, and many used off-label treatments and other interventions (eg, rubbing alcohol and multiple showers daily), which provided limited relief. For many, itching was experienced daily and severely disrupted sleep, daily activities, interactions with others, and mental wellbeing. These findings reveal chronic kidney disease-associated pruritus severely impacts patients and highlights the need for improved management of this condition.

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.

Difelikefalin in the Treatment of Chronic Kidney Disease-Associated Pruritus: A Systematic Review

Chronic kidney disease-associated pruritus (CKD-aP) is a chronic condition that significantly reduces the quality of life of patients with end-stage renal disease. The etiology is not fully understood, but imbalance in the activity of the opioid pathways, including downregulation of the kappa-opioid receptor, may contribute to itching sensation. Difelikefalin is a selective, peripherally acting kappa-opioid receptor (KOR) agonist. Recently, difelikefalin has been approved as a first drug for the treatment of pruritus associated with chronic kidney disease (CKD) in adult hemodialysis patients. A systematic review of currently available clinical trials was performed to assess the efficacy and safety of difelikefalin in patients with uremic pruritus. A literature review was conducted in May 2022 based on the PRISMA 2020 guidelines. The analyzed clinical trials showed that difelikefalin was effective in reducing pruritus in patients as assessed by the Worst Itching Intensity Numerical Rating Scale. Improvement in quality of life assessed on the basis of the Skindex score and the 5-D itch scale was also noticed. The most commonly reported side effects were mild and included nausea, vomiting, dizziness, and diarrhea. Due to its proven efficacy and good safety profile, difelikefalin is a promising drug for the treatment of pruritus in patients with chronic kidney disease.

The relationship between chronic kidney disease–associated pruritus and health-related quality of life: a systematic review

Background

Chronic kidney disease–associated pruritus (CKD-aP) is a common and burdensome condition for end-stage kidney disease (ESKD) patients, especially those receiving haemodialysis. High-quality evidence of the relationship between CKD-aP and health-related quality of life (HRQoL) can therefore inform clinicians and policymakers about treatment choice and reimbursement decisions.

Methods

A systematic literature review and narrative synthesis stratified by study design and HRQoL instrument was conducted to evaluate in adult ESKD patients receiving in-centre haemodialysis the relationship between CKD-aP and HRQoL assessed using multi dimensional generic or condition-specific preference- or non-preference-based measures. MEDLINE, Embase, Web of Science, BIOSIS Citation Index, Cochrane Library and PsycINFO from inception to March 2020 were searched, with two reviewers extracting data independently.

Results

Searches identified 2684 unique records, of which 20 papers relating to 18 unique studies [5 randomised controlled trials (RCTs) and 13 observational studies] were included. HRQoL was assessed using four generic and eight disease-specific measures. The impact of CKD-aP was assessed by comparison of means, linear regression and correlation. Observational studies employing comprehensively adjusted multivariable linear regression largely found associations between CKD-aP severities and HRQoL. Analyses suggest this relationship is partially mediated by the sleep disturbance caused by CKD-aP. RCTs showing improvements in CKD-aP severity were associated with clinically meaningful improvements in HRQoL. Compared with generic measures, disease-specific HRQoL instruments reported greater changes with reduced CKD-aP. Heterogeneity in study design and reporting precluded meta-analysis.

Conclusions

CKD-aP severity was found to be associated with a worsening of HRQoL in the majority of observational and RCT studies. Parallel improvements in CKD-aP and HRQoL with interventions may support their use (PROSPERO registration 175035).