Zinc sulfate for relief of pruritus in patients on maintenance hemodialysis

Antioxidants for adults with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a significant risk factor for cardiovascular disease (CVD) and death. Increased oxidative stress in people with CKD has been implicated as a potential causative factor. Antioxidant therapy decreases oxidative stress and may consequently reduce cardiovascular morbidity and death in people with CKD. This is an update of a Cochrane review first published in 2012.

OBJECTIVES

To examine the benefits and harms of antioxidant therapy on death and cardiovascular and kidney endpoints in adults with CKD stages 3 to 5, patients undergoing dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies until 15 November 2022 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials investigating the use of antioxidants, compared with placebo, usual or standard care, no treatment, or other antioxidants, for adults with CKD on cardiovascular and kidney endpoints.

DATA COLLECTION AND ANALYSIS

Titles and abstracts were screened independently by two authors who also performed data extraction using standardised forms. Results were pooled using random effects models and expressed as risk ratios (RR) or mean difference (MD) with 95% confidence intervals (CI). Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 95 studies (10,468 randomised patients) that evaluated antioxidant therapy in adults with non-dialysis-dependent CKD (31 studies, 5342 patients), dialysis-dependent CKD (41 studies, 3444 patients) and kidney transplant recipients (21 studies, 1529 patients). Two studies enrolled dialysis and non-dialysis patients (153 patients). Twenty-one studies assessed the effects of vitamin antioxidants, and 74 assessed the effects of non-vitamin antioxidants. Overall, the quality of included studies was moderate to low or very low due to unclear or high risk of bias for randomisation, allocation concealment, blinding, and loss to follow-up. Compared with placebo, usual care, or no treatment, antioxidant therapy may have little or no effect on cardiovascular death (8 studies, 3813 patients: RR 0.94, 95% CI 0.64 to 1.40; I² = 33%; low certainty of evidence) and probably has little to no effect on death (any cause) (45 studies, 7530 patients: RR 0.95, 95% CI 0.82 to 1.11; I² = 0%; moderate certainty of evidence), CVD (16 studies, 4768 patients: RR 0.79, 95% CI 0.63 to 0.99; I² = 23%; moderate certainty of evidence), or loss of kidney transplant (graft loss) (11 studies, 1053 patients: RR 0.88, 95% CI 0.67 to 1.17; I² = 0%; moderate certainty of evidence). Compared with placebo, usual care, or no treatment, antioxidants had little to no effect on the slope of urinary albumin/creatinine ratio (change in UACR) (7 studies, 1286 patients: MD -0.04 mg/mmol, 95% CI -0.55 to 0.47; I² = 37%; very low certainty of evidence) but the evidence is very uncertain. Antioxidants probably reduced the progression to kidney failure (10 studies, 3201 patients: RR 0.65, 95% CI 0.41 to 1.02; I² = 41%; moderate certainty of evidence), may improve the slope of estimated glomerular filtration rate (change in eGFR) (28 studies, 4128 patients: MD 3.65 mL/min/1.73 m², 95% CI 2.81 to 4.50; I² = 99%; low certainty of evidence), but had uncertain effects on the slope of serum creatinine (change in SCr) (16 studies, 3180 patients: MD -13.35 µmol/L, 95% CI -23.49 to -3.23; I² = 98%; very low certainty of evidence). Possible safety concerns are an observed increase in the risk of infection (14 studies, 3697 patients: RR 1.30, 95% CI 1.14 to 1.50; I² = 3%; moderate certainty of evidence) and heart failure (6 studies, 3733 patients: RR 1.40, 95% CI 1.11 to 1.75; I² = 0; moderate certainty of evidence) among antioxidant users. Results of studies with a low risk of bias or longer follow-ups generally were comparable to the main analyses.

AUTHORS' CONCLUSIONS

We found no evidence that antioxidants reduced death or improved kidney transplant outcomes or proteinuria in patients with CKD. Antioxidants likely reduce cardiovascular events and progression to kidney failure and may improve kidney function. Possible concerns are an increased risk of infections and heart failure among antioxidant users. However, most studies were of suboptimal quality and had limited follow-up, and few included people undergoing dialysis or kidney transplant recipients. Furthermore, the large heterogeneity in interventions hampers drawing conclusions on the efficacy and safety of individual agents.

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.

Western and complementary alternative medicine treatment of uremic pruritus: A literature review

Uremic pruritus (UP), also called chronic kidney disease-associated pruritus (CKD-aP), is a bothersome symptom that causes sleep disturbance, anxiety, depression, and reduced quality of life. Pruritus often occurs in patients with end-stage renal disease. There is still no definite treatment for UP due to its unclear pathogenesis. We searched electronic databases (PubMed and Google Scholar) and gathered the latest clinical trials and pilot studies of Western and complementary alternative medicine (CAM) therapies for UP in English. These UP studies were separated into three main groups: systemic, topical, and others and CAM. Gabapentin, nalfurafine, acupuncture, and Chinese herbal bath therapy (CHBT) show antipruritic effects, with higher evidence grades in the meta-analysis. Emollients with additive compounds are more effective for reducing itch than emollients without additives. Supplements for deficient elements, such as zinc, omega-3, and omega-6, also show benefits for pruritus improvement. CAM therapies such as acupuncture, herbs, and herbal baths or creams all have good results for UP treatment. We summarize the treatments and suggest a treatment algorithm for UP according to severity. Some UP therapies are already supported by large-scale clinical evidence, and some new treatments can provide patients with new hope and treatment options. However, these new methods still need large population studies and further exploration.

Chronic Kidney Disease-Associated Pruritus: A Review

BACKGROUND

Chronic kidney disease-associated pruritus (CKD-aP), also known as uraemic pruritus, is a disabling symptom for patients and a challenging condition for clinicians. Despite being common amongst end-stage kidney disease (ESKD) patients, it remains underestimated and underdiagnosed. The exact pathogenesis remains largely elusive, which hampers the synthesis of a definite treatment approach.

SUMMARY

Chronic pruritus (lasting 6 weeks or more in duration) is a common and potentially disabling symptom in patients with advanced CKD. A unified hypothesis of pathogenesis has not yet been concluded. Studies have shown changes in the immunochemical milieu of the skin in patients with CKD-aP with several inciting stimuli identified. However, other unrecognized factors are likely to be involved. This article will review the current observations and understanding of the postulated pathogenesis of CKD-aP, as well as the evidence for current management strategies. Key Messages: CKD-aP is a common and troubling symptom amongst ESKD patients that is associated with decreased quality of life and poor prognosis. Its exact pathogenesis, at the time of writing, is not well-understood. A stepwise approach is recommended for management. Systematic reviews show the largest body of evidence was found for the effectiveness of gabapentin. Comparison is needed between newly emerging pharmacological agents such as kappa-opioid receptor agonists and more established agents, such as the gabapentinoids. Finally, renal transplantation should be considered in severe and refractory cases who are suitable transplant candidates as it has shown an excellent outcome in most cases.

Interventions for itch in people with advanced chronic kidney disease

BACKGROUND

Itch in patients with chronic kidney disease (CKD) is common, often very distressing and associated with depression, reduced quality of life, and increased death. The most common first-line treatment has been the use of antihistamines despite the lack of substantial evidence for its use for uraemic itch. Few recommendations and guidelines exist for treatment.

OBJECTIVES

We aimed to determine: 1) the benefits and harms (both absolute and relative) of all topical and systemic interventions for the treatment of uraemic itch, either alone or in combination, when compared with placebo or standard care; and, 2) the dose strength or frequency, stage of kidney disease or method of dialysis used (where applicable) in cases where the effects of these interventions vary depending on co-interventions.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 17 December 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in adults with CKD stages 4 or 5 comparing treatments (pharmacological, topical, exposure, dialysis modality) for CKD associated itch to either placebo or other established treatments.

DATA COLLECTION AND ANALYSIS

Two authors independently abstracted study data and assessed study quality. Data were analysed using a random effects meta-analysis design estimating the relative effects of treatment versus placebo. Estimates of the relative effects between treatments are included where possible. For continuous measures of severity of itch up to three months, mean difference (MD) or standardised mean difference (SMD) were used. When reported, adverse effects were tabulated. The certainty of the evidence was estimated using GRADE.

MAIN RESULTS

Ninety-two RCTs, randomising 4466 participants were included. Fifty-eight studies (3285 participants) provided sufficient data to be meta-analysed. Of these, 30 compared an intervention to a placebo or control. The 10 cm Visual Analogue Scale (VAS) was the dominant instrument utilized for itch reporting and the Duo score was used in a minority of studies. GABA analogues including, gabapentin and pregabalin, reduce itch in patients with CKD (5 studies, 297 participants: 4.95 cm reduction, 95% CI 5.46 to 4.44 lower in VAS compared to placebo; high certainty evidence). Kappa opioid agonists, including nalfurafine also reduced itch in this population (6 studies, 661 participants: 1.05 cm reduction, 95% CI 1.40 to 0.71 lower in VAS compared to placebo; high certainty evidence). Ondansetron had little or no effect on itch scores (3 studies, 183 participants: 0.38 cm reduction, 95% CI 1.04 lower to 0.29 higher in VAS compared to placebo; high certainty evidence). Reduction in the severity of itch was reported with oral montelukast, turmeric, zinc sulfate and topical capsaicin. For all other interventions, the certainty of the evidence was low to moderate, and the interventions had uncertain effects on uraemic pruritus. Six studies have disclosed significant financial support from their respective manufacturers, six were affected by lack of blinding, and 11 studies have 15 participants or less. Older, smaller RCTs often failed to follow intention-to-treat protocols with unexplained dropouts after randomisation. Adverse effects were generally poorly and inconsistently reported across all RCTs. No severe adverse events were reported for any intervention.

AUTHORS' CONCLUSIONS

The RCTs of this meta-analysis contain a large array of interventions with a diverse set of comparators. For many interventions, trials are sparse. This served to make informative meta-analysis challenging. Of all treatments for uraemic pruritus, gabapentinoids (gabapentin and pregabalin) were the most studied and show the greatest reduction in itch scores. Further RCTs, even of the scale of the largest trials included in this review, are unlikely to significantly change this finding. Kappa-opioid agonists (mainly nalfurafine) also may reduce itch, but indirect comparison suggests a much more modest effect in comparison to GABA analogues. Evidence for oral montelukast, turmeric, zinc sulfate, and topical capsaicin also showed an itch score reduction. However, these reductions were reported in small studies, and warrant further investigation. Ondansetron did not reduce itch. It is somewhat unlikely that a further study of ondansetron will change this result.

Renal handling of zinc in chronic kidney disease patients and the role of circulating zinc levels in renal function decline

BACKGROUND

Zinc deficiency is commonly encountered in chronic kidney disease (CKD). The aims of this study were to assess whether zinc deficiency was related to increased renal excretion of zinc and to the progression of CKD.

METHODS

Plasma and 24-h urinary zinc levels, urinary electrolytes and uromodulin were measured in 108 CKD patients and 81 individuals without CKD. Serum creatinine values were collected for 3 years to calculate the yearly change in estimated glomerular filtration rate (eGFR). Multivariable regression analysis was performed to assess the association between baseline zinc levels and yearly change in eGFR.

RESULTS

CKD patients had lower circulating zinc levels and higher 24-h urinary zinc excretion than non-CKD participants (612.4 ± 425.9 versus 479.2 ± 293.0 µg/day; P = 0.02). Fractional excretion (FE) of zinc was higher and it significantly increased at more advanced CKD stages. Zinc FE was correlated negatively with 24-h urinary uromodulin excretion (r=-0.29; P < 0.01). Lower baseline plasma zinc levels were associated with a faster yearly decline of renal function in age, gender, diabetes and hypertension adjusted models, but this relationship was no longer significant when baseline eGFR or proteinuria were included.

CONCLUSIONS

Zinc levels are lower in CKD, and not compensated by reduced renal zinc excretion. The inverse association between urinary zinc excretion and uromodulin possibly points to an impaired tubular activity, which could partly account for zinc imbalance in CKD. These data suggest that zinc status is associated with renal function decline, but further studies elucidating the underlying mechanisms and the potential role of zinc supplements in CKD are needed.

Complementary and alternative medicine therapies for uremic pruritus - A systematic review of randomized controlled trials

INTRODUCTION

Uremic pruritus (UP) is one of the most bothersome symptoms among chronic kidney disease (CKD) patients. The pathophysiology of UP remains elusive, resulting in limited treatment options. The inability of standard medical treatments to provide effective relief has piqued interest in complementary and alternative medicine (CAM).

METHODOLOGY

A systematic review of randomized controlled trials (RCTs) summarizing the efficacy and safety profile of CAM used for UP in CKD patients was performed. CAM interventions were classified using categories proposed by the National Center for Complementary and Integrative Health. The efficacy of each CAM was determined from changes in UP severity and all reported adverse effects were extracted.

RESULTS

Of 5242 articles screened, 34 RCTs were included, with 15 (44.1 %) studies having a sample size greater than 50. The studies considered 21 treatments including omega-3 fatty acid supplementation (n=5), acupuncture (n=5), topical capsaicin (n=4) and acupressure (n=3). Acupuncture, acupressure and topical capsaicin were shown to be effective in improving uremic pruritus. Interventions which include oral omega-3 fatty acid and zinc supplementation demonstrated mixed efficacy. Other therapies such as evening primrose oil, turmeric, vitamin B3, vitamin D and thermal therapy were not effective for treatment of UP. Common adverse effects reported with topical capsaicin included mild burning sensations (50.0-88.2 %) or erythema (6.7-22.7%) while that of acupuncture included soreness (7.5 %), bleeding (6.0-7.5%) and hematoma (1.9 %).

CONCLUSIONS

Acupuncture, acupressure and topical capsaicin have the largest body of evidence for efficacy in the treatment of UP. Larger and higher quality RCTs are required to examine the efficacy and safety of promising CAM.

CKD-Associated Pruritus: New Insights Into Diagnosis, Pathogenesis, and Management

Chronic kidney disease–associated pruritus (CKD-aP) is a common, troubling and in some cases debilitating problem for patients with CKD and end-stage renal disease. Despite a prevalence rate of approximately 20% in CKD and 40% in end-stage renal disease, and a clear association with poorer psychosocial and medical outcomes, this condition is often underreported by patients and overlooked by health care providers. This is likely due, in part, to uncertainty regarding its pathogenesis and treatment. Most commonly, CKD-aP is attributed to toxin build-up, peripheral neuropathy, immune system dysregulation, or opioid dysregulation. Prior treatment studies of CKD-aP have targeted these potential etiologies but have been limited by noncontrolled design, small sample size, and non-uniform definitions of CKD-aP. Recently, several large, randomized controlled trials targeting opioid dysregulation have yielded promising results. These trials have spurred new hope for understanding and treating this condition.

Development and Validation of a Uremic Pruritus Treatment Algorithm and Patient Information Toolkit in Patients With Chronic Kidney Disease and End Stage Kidney Disease

CONTEXT

Uremic pruritus (UP) affects up to half of all patients with kidney disease and has been independently associated with poor patient outcomes. UP is a challenging symptom for clinicians to manage as there are no validated guidelines for its treatment.

OBJECTIVES

The study aimed to develop and validate an algorithm and patient information toolkit for the treatment of UP in patients with kidney disease.

METHODS

The study involved a literature search and development of an initial draft algorithm, followed by content and face validation of this algorithm. Validation entailed three rounds of interviews with six nephrology clinicians per round. Participants assessed the relevance of each component of the algorithm and then rated a series of statements on a scale of 1-5 to assess face validity of the algorithm. After each round, the content validity index (CVI) of each algorithm component was calculated, and the algorithm was revised by the study team in response to findings. This process was followed by a second study that developed and validated a patient information pamphlet and video.

RESULTS

Algorithm validation participants were affiliated with three institutions and included seven physicians, four registered nurses, three nurse practitioners, three pharmacists, and a dietician. The average CVI of the algorithm components across all three rounds was 0.89, with 0.80 commonly cited as the lower acceptable limit for content validation. More than 78% of participants rated each face validity statement as "Agree" or "Strongly Agree". For the patient information tools, five clinicians and 15 patients were included in validation. The average CVI was 1.00 for both tools, and the average face validity was 92%.

CONCLUSION

A treatment algorithm and patient information toolkit for managing UP in patients with kidney disease were developed and validated through expert review. Further research will be conducted on implementation of the treatment algorithm and evaluating patient-reported outcomes.

Omega-3 Supplementation Improves Pruritus in Continuous Ambulatory Peritoneal Dialysis Patients: A Crossover Randomized Pilot Clinical Trial

Objective:

Pruritus is a prevalent skin condition in end-stage renal disease patients. Omega-3 fatty acids have been shown to reduce pruritus in hemodialysis patients. Our objective was to assess the effect of 3 g/day omega-3 supplementation on pruritus among continuous ambulatory peritoneal dialysis (CAPD) patients.

Methods:

In this two-period, two-sequence crossover randomized clinical trial, 40 eligible subjects (CAPD patients who complained of pruritus for more than 8 weeks) were randomized to 3 g of omega-3 (n = 20) or identical placebo capsules (n = 20) for 4 weeks. After a wash-out period of 6 weeks, patients were crossed over to the alternate treatment option. Pruritus intensity was assessed using the visual analog scale (VAS) at baseline, 2-and 4-weeks post-intervention in each study period. Both patients and investigators were blinded to the study protocol.

Findings:

No significant carry-over effect was detected. The mean pruritus score (VAS) in the omega-3 group compared with placebo group after the first (−3.02 vs. −0.48, P < 0.001) and second (−4.09 vs. −0.43, P < 0.001) intervention periods showed higher significant decrease.

Conclusion:

In summary, omega-3 supplementation is an effective treatment for pruritus alleviation in CAPD patients. Further studies are needed to determine the mechanisms underlying antipruritic effects of omega-3.

International Comparisons of Prevalence, Awareness, and Treatment of Pruritus in People on Hemodialysis

BACKGROUND AND OBJECTIVES

Uremic pruritus in patients on hemodialysis is associated with depression, lower quality of life, and mortality. We studied the prevalence, awareness, and treatment of pruritus to assess how well this important condition is currently managed internationally.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from 35,452 patients on hemodialysis in up to 17 countries from the Dialysis Outcomes and Practice Patterns Study were analyzed to describe pruritus prevalence from 1996 to 2015. Data from 6256 patients and 268 medical directors in 17 countries in 2012-2015 were analyzed to describe predictors, effects, medical directors' awareness, and treatment of pruritus.

RESULTS

Patients very much or extremely bothered by itching declined from 28% in 1996 to 18% in 2015. In 2012-2015, among patients nearly always or always bothered by itching, pruritus had a major effect on work and social life; 18% used no treatment for pruritus, and 17% did not report itching to health care staff. In total, 69% of medical directors underestimated the prevalence of pruritus in their unit. Managing high serum phosphorus and low Kt/V was ranked as the most important intervention, but no relationship was found between these factors and pruritus; 57% of medical directors used oral antihistamines for first-line chronic treatment of pruritus. Gabapentin was used by 45% as first-, second-, or third-line treatment. Nalfurafine was only used in Japan.

CONCLUSIONS

The prevalence of pruritus in people on hemodialysis is decreasing but remains underestimated. Large numbers of patients on hemodialysis with severe pruritus do not receive treatment. There is wide variation in the use of unlicensed medications for the treatment of pruritus. These data provide a benchmark for initiatives to improve the management of uremic pruritus.

MULTIMEDIA

This article contains multimedia at https://vimeo.com/49458473This article contains multimedia at vimeo.com/49455976.

Association between itching and the serum zinc levels in patients with varicose veins

Background

Varicose veins commonly occur in the lower extremities and can cause pain and discomfort in the affected area. Many patients with varicose veins suffer from itching, but its cause has not been sufficiently explained. In recent years, the role of zinc in maintaining the integrity of skin has been reported, and zinc supplementation has been suggested to be effective in relieving itching. The objective of this study is to elucidate the relationship between itching and serum zinc concentration in patients with varicose veins.

Methods

We measured the stratum corneum water content, TEWL and zinc levels in each participant. The study subjects were 11 patients with varicose veins who were experiencing itching (2 males and 9 females, mean age: 65.9 ± 9.4 years old) and 13 patients without itching (6 males and 7 females, mean age: 59.3 ± 9.5 years old). The control group was comprised of 9 healthy individuals without varicose veins (mean age: 41.7 ± 7.0 years old).

Results

The level of stratum corneum water content was significantly lower in the patients experiencing itching compared to those without the symptom, and it was significantly lower in both patient groups than in the control group. Transepidermal water loss (TEWL) was significantly higher in the patients experiencing itching than those without the symptom, and it was significantly higher in both patient groups than in the control group. In addition, zinc level was significantly lower in the patients with itching compared to those without itching or the control group. For all study participants, relationships between the stratum corneum water content and TEWL against serum zinc were examined. There was a positive correlation between the stratum corneum water content and serum zinc, and a negative correlation was found between TEWL and serum zinc.

Conclusion

Our novel findings suggested that the development of varicose veins leads to decrease in serum zinc, causing dry skin which could contribute to itching.

Treatment of Uremic Pruritus: A Systematic Review

BACKGROUND

Uremic pruritus is a common and burdensome symptom afflicting patients with advanced chronic kidney disease (CKD) and has been declared a priority for CKD research by patients. The optimal treatments for uremic pruritus are not well defined.

STUDY DESIGN

Systematic review.

SETTING & POPULATION

Adult patients with advanced CKD (stage ≥ 3) or receiving any form of dialysis.

SELECTION CRITERIA FOR STUDIES

PubMed, CINAHL, Embase, International Pharmaceutical Abstracts, Scopus, Cochrane Library, and ClinicalTrials.gov from their inception to March 6, 2017, were systematically searched for randomized controlled trials (RCTs) of uremic pruritus treatments in patients with advanced CKD (stage ≥ 3) or receiving any form of dialysis. 2 reviewers extracted data independently. Risk of bias was assessed using the Cochrane Collaboration risk-of-bias tool.

INTERVENTION

Any intervention for the treatment of uremic pruritus was included.

OUTCOMES

A quantitative change in pruritus intensity on a visual analogue, verbal rating, or numerical rating scale.

RESULTS

44 RCTs examining 39 different treatments were included in the review. These treatments included gabapentin, pregabalin, mast cell stabilizers, phototherapy, hemodialysis modifications, and multiple other systemic and topical treatments. The largest body of evidence was found for the effectiveness of gabapentin. Due to the limited number of trials for the other treatments included, we are unable to comment on their efficacy. Risk of bias in most studies was high.

LIMITATIONS

Heterogeneity in design, treatments, and outcome measures rendered comparisons difficult and precluded meta-analysis.

CONCLUSIONS

Despite the acknowledged importance of uremic pruritus to patients, with the exception of gabapentin, the current evidence for treatments is weak. Large, simple, rigorous, multiarm RCTs of promising therapies are urgently needed.

Chronic kidney disease-associated pruritus: impact on quality of life and current management challenges

Chronic kidney disease-associated pruritus (CKD-aP) is a distressing, often overlooked condition in patients with CKD and end-stage renal disease. It affects ~40% of patients with end-stage renal disease and has been associated with poor quality of life, poor sleep, depression, and mortality. Prevalence estimates vary based on the instruments used to diagnose CKD-aP, and standardized diagnostic instruments are sorely needed. Treatment studies have often yielded conflicting results. This is likely related to studies that are limited by small sample size, flawed designs, and nonstandardized diagnostic instruments. Several large well-designed treatment trials have recently been completed and may soon influence CKD-aP management.

Pharmacological interventions for pruritus in adult palliative care patients

BACKGROUND

This is an update of the original Cochrane review published in 2013 (Issue 6). Pruritus occurs in patients with disparate underlying diseases and is caused by different pathologic mechanisms. In palliative care patients, pruritus is not the most prevalent but is one of the most puzzling symptoms. It can cause considerable discomfort and affects patients' quality of life.

OBJECTIVES

To assess the effects of different pharmacological treatments for preventing or treating pruritus in adult palliative care patients.

SEARCH METHODS

For this update, we searched CENTRAL (the Cochrane Library), and MEDLINE (OVID) up to 9 June 2016 and Embase (OVID) up to 7 June 2016. In addition, we searched trial registries and checked the reference lists of all relevant studies, key textbooks, reviews and websites, and we contacted investigators and specialists in pruritus and palliative care regarding unpublished data.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) assessing the effects of different pharmacological treatments, compared with a placebo, no treatment, or an alternative treatment, for preventing or treating pruritus in palliative care patients.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the identified titles and abstracts, performed data extraction and assessed the risk of bias and methodological quality. We summarised the results descriptively and quantitatively (meta-analyses) according to the different pharmacological interventions and the diseases associated with pruritus. We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created 10 'Summary of findings' tables.

MAIN RESULTS

In total, we included 50 studies and 1916 participants in the review. We added 10 studies with 627 participants for this update. Altogether, we included 39 different treatments for pruritus in four different patient groups.The overall risk of bias profile was heterogeneous and ranged from high to low risk. However, 48 studies (96%) had a high risk of bias due to low sample size (i.e. fewer than 50 participants per treatment arm). Using GRADE criteria, we downgraded our judgement on the quality of evidence to moderate in seven and to low in three comparisons for our primary outcome (pruritus), mainly due to imprecision and risk of bias.In palliative care participants with pruritus of different nature, the treatment with the drug paroxetine, a selective serotonin reuptake inhibitor, reduced pruritus by 0.78 points (numerical analogue scale from 0 to 10; 95% confidence interval (CI) -1.19 to -0.37; one RCT, N = 48, quality of evidence: moderate) compared to placebo.For participants suffering from uraemic pruritus (UP), gabapentin was more effective than placebo (visual analogue scale (VAS): 0 to 10), mean difference (MD) -5.91, 95% CI -6.87 to -4.96; two RCTs, N = 118, quality of evidence: moderate). The κ-opioid receptor agonist nalfurafine showed amelioration of UP (VAS 0 to 10, MD -0.95, 95% CI -1.32 to -0.58; three RCTs, N = 422, quality of evidence: moderate) and only few adverse events. Moreover, cromolyn sodium relieved UP participants from pruritus by 2.94 points on the VAS (0 to 10) (95% CI -4.04 to -1.83; two RCTs, N = 100, quality of evidence: moderate) compared to placebo.In participants with cholestatic pruritus (CP), data favoured rifampin (VAS: 0 to 100, MD -24.64, 95% CI -31.08 to -18.21; two RCTs, N = 42, quality of evidence: low) and flumecinol (RR > 1 favours treatment group; RR 1.89, 95% CI 1.05 to 3.39; two RCTs, N = 69, quality of evidence: low) and showed a low incidence of adverse events in comparison with placebo. The opioid antagonist naltrexone reduced pruritus for participants with CP (VAS: 0 to 10, MD -2.26, 95% CI -3.19 to -1.33; two RCTs, N = 52, quality of evidence: moderate) compared to placebo. However, effects in participants with UP were inconclusive (percentage difference -12.30%, 95% CI -25.82% to 1.22%, one RCT, N = 32). Furthermore, large doses of opioid antagonists (e.g. naltrexone) could be inappropriate in palliative care patients because of the risk of reducing analgesia.For participants with HIV-associated pruritus, it is uncertain whether drug treatment with hydroxyzine hydrochloride, pentoxifylline, triamcinolone or indomethacin reduces pruritus because the evidence was of very low quality (e.g. small sample size, lack of blinding).

AUTHORS' CONCLUSIONS

Different interventions tended to be effective for CP and UP. However, therapies for patients with malignancies are still lacking. Due to the small sample sizes in most meta-analyses and the heterogeneous methodological quality of the included trials, the results should be interpreted cautiously in terms of generalisability.

Drug treatments for pruritus in adult palliative care

BACKGROUND

Pruritus is a rare but troublesome symptom in palliative-care patients with a variety of underlying diseases. The pharmacotherapy of pruritus is often off-label, and an evidence-based evaluation is needed.

METHODS

A Cochrane Review published in 2013 was updated with a systematic literature search up to January 2014. Randomized and controlled trials (RCTs) with adult palliative-care patients were included.

RESULTS

In the 43 RCTs that were analyzed, three of which were more recent than the Cochrane Review, 8 clinically relevant active substances were investigated in a total of 19 RCTs. Effective drugs for pruritus in palliative-care patients included paroxetine for pruritus of diverse origins (1 RCT; strong effect) and indomethacin for HIV-induced prutitus (1 RCT; median effect = moderate reduction). Effective drugs for pruritus in uremia were gabapentin (2 RCTs; strong effect), nalfurafin (3 RCTs; moderate effect), naltrexone (3 RCTs; heterogeneous effects, ranging from weak to strong), and cromoglicic acid (2 RCTs; moderate to strong effect). Effective drugs for cholestatic pruritus were rifampicin (3 RCTs; moderate effect), flumecinol (2 RCTs; weak to moderate effect), and naltrexone (2 RCTs; moderate to strong effect). Undesired effects were most common with naltrexone (dizziness: 0% -50% , nausea: 0% -50% ) and nalfurafin (nasopharyngitis: 8% -12% , insomnia: 7% -15%).

CONCLUSION

In view of the diverse etiologies of pruritus in palliative-care patients, careful consideration should be given to the choice of drug used to treat it. The substances listed here have moderate to strong antipruritic effects and merit further study in RCTs of high methodological quality.

Pharmacological interventions for pruritus in adult palliative care patients

BACKGROUND

Pruritus is not the most prevalent but one of the most puzzling symptoms in palliative care patients. It can cause considerable discomfort and has a major impact on patients' quality of life. In the field of palliative care, pruritus is a symptom occurring in patients with disparate underlying diseases and based on different pathologic mechanisms but ending in the same phenomenon. The pathogenesis of pruritus is complex and not fully elucidated. Thus, it is still very difficult to treat pruritus effectively. Evidence-based treatment approaches are needed.

OBJECTIVES

The objective was to evaluate the efficacy of different pharmacological treatments for preventing or treating pruritus in adult palliative care patients.

SEARCH METHODS

A systematic literature search up to January 2012 was performed and it was updated in August 2012. The following databases were searched: The Cochrane Library (CENTRAL, DARE, CDSR) (2012, issue 8 of 12); MEDLINE (1950 to August 2012); EMBASE (1980 to August 2012) and three other databases. In addition, we searched trials registries and checked the reference lists of all relevant studies, key textbooks, reviews, and websites, and contacted investigators and specialists in pruritus and palliative care regarding unpublished data.

SELECTION CRITERIA

We included randomised controlled trials assessing the effects of different pharmacological treatments on preventing or treating pruritus in palliative care patients.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed identified titles and abstracts. Three independent review authors performed assessment of all potentially relevant studies, data extraction, assessment of risk of bias and methodological quality. Results were summarised descriptively according to the different pharmacological interventions and the type of underlying pruritus. Where possible, results were presented in meta-analyses.

MAIN RESULTS

In total, 38 reports comprising 40 studies and 1286 participants were included in the review. Altogether, 30 different treatments for pruritus in four different patient groups were included.The findings of this review indicated that the treatment of pruritus for palliative care patients is challenging and requires an individualistic approach. Results showed that effective therapeutic choices have to be guided by the pathophysiology of the pruritus. Various forms of pruritus occur, especially in the field of palliative care, and sometimes the origin of the pruritus is difficult to determine. Therefore, identifying the underlying cause of pruritus is of prime importance in order to develop tailored treatment plans, even if in palliative care the treatment is focused towards the symptom and not necessarily the underlying disease.Results show that in palliative care patients with pruritus of different natures, treatment with the drug paroxetine, a selective serotonin reuptake inhibitor, may be beneficial. For patients suffering from pruritus associated with HIV infection, indomethacin was described as the most effective drug, although the evidence was weak. For patients suffering from chronic kidney disease-associated pruritus, gabapentin may be an option. An alternative treatment for this patient group seems to be the κ-opioid receptor agonist nalfurafine, which has shown significant amelioration of pruritus and acceptable adverse effects. As they have exhibited a low incidence of adverse effects, rifampicin and flumecinol may be recommended for patients with cholestatic pruritus. The opioid antagonist naltrexone has been shown to offer a therapeutic alternative for patients suffering from uraemic or cholestatic pruritus. However, these drugs are often inappropriate in the palliative population because of the risk of reducing analgesia when giving high doses of naltrexone.

AUTHORS' CONCLUSIONS

The findings of this review indicate that the number of systemic and topical drugs used for the different subforms of pruritus is increasing. Different interventions have been shown to be effective in the treatment of pruritus of different origins. Nevertheless, an optimal therapy for pruritus is constrained due to the limited understanding of crucial itch mediators and receptors in the various subforms of itch. Ideal antipruritic therapies are still lacking, especially for palliative care patients.This systematic review also indicates that there is insufficient evidence to give any concrete recommendations regarding treatment of pruritus in palliative care patients. Due to the very small sample sizes and poor methodological quality of the majority of studies that were included, the results of this review need to be interpreted with caution. Furthermore, the generalizability is questionable. Additional studies, and particularly carefully designed treatment trials, are needed to provide valid evidence for adequate treatment of pruritus in palliative care patients.