Health-Related QOL and Economic Burden of Chronic Pruritus

Treatment of Common Dermatologic Conditions

Dermatologic concerns are discussed in about a third of all primary care visits. This review discusses treatments for common dermatologic diagnoses addressed in primary care settings, with an emphasis on new and emerging treatments. Topical, oral, and injectable treatment of common forms of alopecia, facial rashes, atopic dermatitis, psoriasis, seborrheic dermatitis, and stasis dermatitis will be discussed to help increase comfort in prescribing and alert providers to common side effects or complications of more intensive treatments used by dermatologists.

Plasma metabolomic profiling reveals a novel circulating biomarker signature in chronic pruritus of unknown origin

Chronic pruritus of unknown origin (CPUO) is characterized by chronic itch for 6 weeks or greater without an identifiable primary cause. Studies are needed to investigate circulating blood biomarkers to elucidate disease pathogenesis. The objective of this study was to investigate changes in circulating blood metabolites in CPUO patients and to identify potential therapeutic targets. Our cross-sectional study collected plasma from 11 CPUO patients and 11 matched control patients for mass-spectrometry based metabolite data analysis. 15 metabolites differed significantly in the blood of CPUO patients compared to controls, including nine amino acids (isoleucine, L-tyrosine, threonine, DL-tryptophan, L-valine, methionine, glycine, lysine, and L-phenylalanine), four amino acid derivatives (creatinine, DL-carnitine, acetyl-L-carnitine, and indole-3-acrylic acid), and two aromatic and fatty acid derivatives (2-hydroxycinnamic acid and oleamide). These metabolites were also correlated with itch severity. Metabolic set enrichment analysis (MSEA) identified downregulation of several pathways in CPUO: phenylalanine, tyrosine, tryptophan biosynthesis; catecholamine biosynthesis; and glycine, serine, and threonine metabolism. Our study identified decreases in several circulating plasma metabolites in CPUO patients and downregulation of pathways related to catecholamine biosynthesis and tryptophan biosynthesis, providing insight into the pathogenesis of CPUO.

Efficacy and Safety of Abrocitinib in Prurigo Nodularis and Chronic Pruritus of Unknown Origin: A Nonrandomized Controlled Trial

Importance

Prurigo nodularis (PN) and chronic pruritus of unknown origin (CPUO) are chronic pruritic diseases that dramatically impair quality of life, but therapeutic options are limited. Abrocitinib, a Janus kinase 1 inhibitor, represents a promising therapy for both conditions.

Objective

To assess the efficacy and safety of 200-mg oral abrocitinib administered once daily in adults with moderate to severe PN or CPUO.

Design, Setting, and Participants

This phase 2, open-label, nonrandomized controlled trial conducted between September 2021 and July 2022 took place at a single center in the US. A total of 25 adult patients with moderate to severe PN or CPUO were screened. Ten patients with PN and 10 patients with CPUO were enrolled. All 20 patients completed the 12-week treatment period, 18 of whom completed the 4-week follow-up period.

Intervention

Abrocitinib, 200 mg, by mouth once daily for 12 weeks.

Main Outcomes and Measures

The primary efficacy end point was the percent change in weekly Peak Pruritus Numerical Rating Scale (PP-NRS) scores from baseline to week 12. Key secondary end points included the percentage of patients achieving at least a 4-point reduction in weekly PP-NRS score from baseline to week 12 and the percent change in Dermatology Life Quality Index (DLQI) scores.

Results

A total of 10 patients with PN (mean [SD] age, 58.6 [13.1] years; all were female) and 10 patients with CPUO (mean [SD] age, 70.7 [5.6] years; 2 were female) enrolled in the study. The mean (SD) baseline PP-NRS score was 9.2 (1.0) for PN and 8.2 (1.2) for CPUO. PP-NRS scores decreased by 78.3% in PN (95% CI, -118.5 to -38.1; P < .001) and 53.7% in CPUO (95% CI, -98.8 to -8.6; P = .01) by week 12. From baseline to week 12, 8 of 10 patients with PN and 6 of 10 patients with CPUO achieved at least a 4-point improvement on the PP-NRS. Both groups experienced significant improvement in quality of life as demonstrated by percent change in DLQI scores (PN: -53.2% [95% CI, -75.3% to -31.1%]; P = .002; CPUO: -49.0% [95% CI, -89.6% to -8.0%]; P = .02). The most common adverse event among patients was acneiform eruption in 2 of 20 patients (10%). No serious adverse events occurred.

Conclusions and Relevance

The results of this nonrandomized controlled trial suggest that abrocitinib monotherapy may be effective and tolerated well in adults with PN or CPUO. Randomized, double-blind, placebo-controlled trials are warranted to validate these findings.

Trial Registration

ClinicalTrials.gov Identifier: NCT05038982.

Consensus on the diagnostic algorithm for chronic nodular prurigo

Chronic nodular prurigo (CNP) is a chronic dermatological disease characterized by the presence of chronic pruritus and pruritic nodular lesions. The aim of this study was to reach consensus among a group of experts based on a non-systematic literature review and an algorithm for the clinical diagnosis of CNP. The resulting algorithm is structured in 3 blocks: 1) early identification of the patient with a possible diagnosis of CNP; 2) diagnosis and assessment of CNP; and 3) categorization of CNP (identification of the underlying causes or associated comorbidities). We believe that this clinical algorithm can facilitate the correct diagnosis of patients with CNP. Additionally, it raises awareness on the need for a multidisciplinary approach and specific treatment of CNP, steps of paramount importance to make better therapeutic decisions.

The relationship and clinical significance of serum cytokine expression level and skin pruritus in patients with Hodgkin lymphoma and angioimmunoblastic T-cell lymphoma

Pruritus of lymphoma is commonly associated with both Hodgkin lymphoma (HL) and angioimmunoblastic T cell lymphoma (AITL) and critically affects the life quality of patient. Recent evidence suggests that the pruritogenic cytokines seem to play a significant role in the genesis of chronic. This study aims to investigate the cytokines associated with itching in lymphoma patients and provide the basis for potential therapeutic targets. Serum samples were collected from 60 lymphoma patients, including 47 with Hodgkin lymphoma (HL) and 13 with angioimmunoblastic T-cell lymphoma (AITL), serving as the observation group (lymphoma group, LP group, n = 60). Additionally, serum samples from 8 healthy donors (HD group, n = 8) were collected for comparison. Within the lymphoma group, patients were stratified into those with pruritus (LWP group, n = 30) and those without pruritus (LWOP group, n = 30) based on the presence of skin pruritus symptoms. Elevated levels of multiple cytokines were significantly observed in the LP group in comparison to the HD group (p < 0.01). Patients in LWP group exhibited higher serum levels of IL-31 (p < 0.001), IL-1β (P = 0.039), and IL-1α (P = 0.037) compared to LWOP group. Notably, serum IL-31 levels were higher in advanced AITL patients (stage IV) than in early AITL patients (stage I-Ⅲ, P < 0.05). In subgroup analysis, patients with pruritus in the AITL group exhibited higher serum levels of MIG and CTACK compared to HL group, whereas PDGF-BB levels were significantly lower (p < 0.05). Elevated serum levels of IL-31, IL-1β, and IL-1α are linked to lymphoma-associated pruritus. Differences in serum cytokine profiles between HL and AITL subgroups are also highlighted. These findings offer valuable insights for clinical intervention in managing lymphoma-related pruritus.

Increased cardiovascular risks and mortality in prurigo nodularis: a global cohort study

BACKGROUND

Prurigo nodularis (PN) presents with intensely itchy hard nodules. Despite being limited to the skin, PN was noted to be associated with systemic diseases including diabetes and chronic renal failure. In previous smaller retrospective studies, several cardiac and vascular diseases were found more frequently in patients with PN. However, small cohort sizes, partially discrepant outcomes, missing data, and incomplete risk assessment limit these findings.

METHODS

Electronic health records (EHR)s of 64,801 patients (59.44% females) with PN and an equal sized propensity-matched control group were retrieved. In these cohorts, the risks to develop cardiac and vascular diseases and mortality following the diagnosis of PN were determined. Sub-analyses included stratification for sex, ethnicity, and treatments.

FINDINGS

PN was associated with a higher risk for a broad range of acute cardiac events including heart failure and myocardial infarction. For example, the hazard ratio of myocardial infarction was 1.11 (95%-CI: 1.041-1.184, p = 0.0015) following PN diagnosis. Also, all-cause mortality was higher in patients with PN. Further, chronic vascular as well as structural heart diseases, e.g., peripheral arterial disease, chronic ischaemic heart disease and valval disorders were found more frequently following a PN diagnosis. Risks were more pronounced in white and female patients. Having established an increased risk for death and cardiovascular disease, we next addressed if dupilumab that has been recently licenced for use in this indication can modulate these risks. The risk of death but not of any cardiovascular disease was slightly reduced in patients with PN treated with dupilumab as opposed to those treated with systemic therapies other than dupilumab. The study is limited by retrospective data collection and reliance on ICD10-disease classification.

INTERPRETATION

PN is associated with higher mortality and an increased risk for the development of a wide range of cardiac and vascular diseases. Health care professionals should take this into account when managing patients with PN.

FUNDING

This work was supported by the University of Lübeck, the Deutsche Forschungsgemeinschaft and the State of Schleswig-Holstein.

Comprehensive Study of Drug-Induced Pruritus Based on Adverse Drug Reaction Report Database

Drug-induced pruritus triggers a desire to scratch, thereby diminishing one's quality of life. Certain instances of this phenomenon follow complex mechanisms of action that diverge from histamine-mediated pathways, known contributors to pruritus. However, investigations into the relationship between drugs and pruritus are limited. In this study, data mining techniques were employed to comprehensively analyze the characteristics of drugs linked to pruritus, using the FDA's Adverse Event Reporting System (FAERS) data. Reports linked to pruritus demonstrated noteworthy differences in gender, age, and weight when compared with non-pruritus cases. Among the leading candidates for drugs prompting pruritus were ophthalmic drugs, systemic antibacterials, contrast media, dermatological antifungals, and dermatological preparations. A principal component analysis showed that the second principal component served as an indicator for distinguishing between onsets at mucous membranes or the skin's surface. Additionally, the third principal component functioned as an indicator for categorizing administration methods as either invasive or noninvasive. Furthermore, a hierarchical cluster analysis conducted on these obtained principal components revealed the potential for classifying drugs based on the site of pruritus onset and the method of drug administration. These findings contribute to the development of targeted prevention and treatment strategies for avoiding pruritus in clinical practice.

Relationship Between Standardized Measures of Chronic Kidney Disease-associated Pruritus Intensity and Health-related Quality of Life Measured with the EQ-5D Questionnaire: A Mapping Study

Chronic kidney disease-associated pruritus is linked with decreased health-related quality of life assessed using disease-specific instruments. The extent to which worsening pruritus reduces generic quality of life assessed using the EQ-5D instrument is unknown. Prevalent kidney failure patients receiving in-centre haemodialysis from 5 centres completed the EQ-5D-5L quality of life measure, worst Itching Intensity Numerical Rating Scale and 5-D itch pruritus instruments. Latent class models were used to identify clusters of patients with similarly affected body parts, and mixture models were used to map the pruritus measures to the EQ-5D. Data on 487 respondents were obtained. Latent class analysis identified 3 groups of patients who had progressively worsening severity and an increasing number of body parts affected. Although the worst itching intensity numerical rating scale and 5-D itch instruments correlated with each other, only the latter had a strong relationship with EQ-5D. When controlling for age, sex, diabetes and years receiving dialysis, the meanpredicted EQ-5D utility (1: perfect health, 0: dead) decreased progressively from 0.69 to 0.41. These findings suggest that pruritus instruments that include domains capturing how the individual is physically, mentally and socially affected by their pruritus, in addition to severity, more closely approximate the EQ-5D generic quality of life measure.

Reduced serum pyridoxine and 25-hydroxyvitamin D levels in adults with chronic pruritic dermatoses

Little is known about the role nutritional factors play in the pathogenesis of chronic pruritic dermatoses (CPD). In this study, we analyzed nutritional deficiencies in CPD patients compared to matched controls. We conducted a population-based study from the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2006. The main outcomes of the study were laboratory data on serum vitamin levels in participants who answered affirmatively to the questionnaires on CPD as well as matched healthy controls. We identified 877 cases of CPD among 9817 adults in the US aged 20 to 59 years. These findings revealed a slightly higher percentage of females with CPD. Low vitamin B6 (OR 0.697; 95% CI: 0.696-0.699, p = 0.025) and vitamin D (OR 0.794; 95% CI: 0.789-0.799, p = 0.037) levels were associated with a higher rate of CPD compared to healthy controls. Our study suggests that low levels of Vitamin B6 and Vitamin D inversely correlates with the presence of CPD. These vitamin deficiencies suggest further studies on the effect of vitamin supplementation may help in patients with CPD.

Clinical aspects and management of chronic itch

Chronic pruritus (CP) (ie, itch that persists for more than 6 weeks) poses significant challenges to patients' health and quality of life. It is a common reason for visits to dermatologists and general practitioners and can be caused by a range of conditions, including systemic diseases such as chronic kidney disease or liver diseases, malignancies, neuropathic conditions, and dermatoses such as atopic dermatitis. CP often does not develop in parallel with the course of the disease and can become an entity of its own, which must be treated with antipruritic drugs, even if the underlying cause is already under therapy. Depending on the etiology of CP, different pathways in the pathogenesis have been analyzed recently, following which new treatments have been developed and tested in randomized controlled trials. This article discusses the recent results of these studies and highlights how best to manage health care for patients with CP.

A Review on the Safety of Using JAK Inhibitors in Dermatology: Clinical and Laboratory Monitoring

Janus kinase (JAK) inhibitors are disease-modifying agents with efficacy in treating a spectrum of burdensome dermatologic conditions. The US Food and Drug Administration (FDA) recently placed a black box warning on this class of medications due to safety concerns based on data from studies investigating tofacitinib in patients with rheumatoid arthritis. Here we provide an overview of the timeline of FDA approval of JAK inhibitors in dermatology. We also discuss the available safety profiles of approved oral JAK1 inhibitors, namely abrocitinib and upadacitinib, oral baricitinib, a JAK1/2 inhibitor, deucravacitinib, a Tyk2 inhibitor, and the topical JAK1/2 inhibitor ruxolitinib in dermatology patients. Additionally, we offer suggestions for initial screening and laboratory monitoring for patients receiving JAK inhibitors. We found that the rates of venous thromboembolism reported in trials ranged from no events to 0.1-0.5% in dermatology-specific phase 3 clinical trials compared with no events in the placebo. The rates of cardiovascular events ranged from no events to 0.4-1.2% compared with no events to 0.5-1.2% in the placebo. The rates of serious infections were 0.4-4.8% compared with no events to 0.5-1.3% in the placebo. The rates of nonmelanoma skin cancer (NMSC) ranged from no event to 0.6-0.9% compared with no events in the placebo. The rates of non-NMSC ranged from no event to 0.2-0.7% compared with no event to 0.6% in the placebo. Most patients who developed these adverse events had risk factors for the specific event. The most common adverse events of oral JAK inhibitors included upper respiratory infections, nasopharyngitis, nausea, headache, and acne. Dermatologists should consider patients' baseline risk factors for developing serious complications when prescribing oral JAK inhibitors.

Association between Pruritus and Psychosocial Well-being: A Population-based Study among 6,809 Subjects

Pruritus has an extensive impact on functional, social and psychosocial behaviour. The association between pruritus and psychological well-being has mostly been studied among selected patient groups, whereas population-based studies are lacking. The aim of this study was to determine the association between pruritus and insomnia, quality of life, depression and anxiety at the population level in the general population. A cross-sectional population-based study was conducted in 2012 to 2013. Study subjects (n = 6,809) belonging to the Northern Finland Birth Cohort 1966 Study participated in a large follow-up study at the age of 45-47 years. They completed an extensive health questionnaire including questions on pruritus and several previously validated questionnaires regarding symptoms of psychosocial well-being. Pruritus affected 19.9% of the study subjects weekly, being more common in women than in men (p < 0.001). A significant association was found between both localized and generalized pruritus and symptoms of insomnia, depression, anxiety and decreased quality of life. The association was seen even in those with mild psychological symptoms/insomnia, and it affected both sexes. The severity of psychological symptoms increased with increasing frequency of pruritus. In conclusion, pruritus has a multiple effect on psychosocial well-being. Physicians should consider possible psychosocial symptoms in patients with pruritus.

Rapid pruritus reduction with ruxolitinib cream treatment in patients with atopic dermatitis

BACKGROUND

Ruxolitinib cream is a topical formulation of ruxolitinib, a Janus kinase (JAK) 1/JAK2 inhibitor.

OBJECTIVES

To report timing and magnitude of effect of ruxolitinib cream on itch in patients with atopic dermatitis (AD), a highly pruritic inflammatory skin disease.

METHODS

Two phase 3 trials (TRuE-AD1 [NCT03745638]/TRuE-AD2 [NCT03745651]) enrolled patients aged ≥12 years with AD for ≥2 years, Investigator's Global Assessment score of 2 or 3, and 3%-20% affected body surface area. Patients (total N = 1249; median age, 32 years) were randomised (2:2:1) to twice daily 0.75% ruxolitinib cream, 1.5% ruxolitinib cream or vehicle cream for 8 weeks of double-blinded treatment. Worst itch was measured using the numerical rating scale (NRS).

RESULTS

Significantly more patients who applied ruxolitinib cream (either strength) achieved a ≥2-point itch reduction (NRS2) within approximately 12 h versus vehicle (0.75%/1.5% ruxolitinib cream, 16.3%/13.1%; vehicle, 6.9%; both P < 0.05), with further improvements through Week 8 (58.3%/65.1% vs 29.4%; both P < 0.0001). A ≥4-point itch reduction (NRS4) was achieved by significantly more patients who applied 0.75%/1.5% ruxolitinib cream versus vehicle by Day 2 (8.9%/11.2% vs 2.1%; P < 0.005); higher rates were observed at Week 8 (41.5%/51.5% vs 15.8%; P < 0.0001). Median time for the 0.75%/1.5% ruxolitinib cream groups to achieve NRS4 from baseline was 15.0/13.0 days; this endpoint was not reached by the vehicle group.

CONCLUSIONS

Ruxolitinib cream demonstrated rapid improvement in itch in patients with mild to moderate AD that was sustained for 8 weeks. Significantly more patients applying ruxolitinib cream achieved itch NRS2 within approximately 12 h and itch NRS4 by Day 2 versus vehicle.

In vitro models for investigating itch

Itch (pruritus) is a sensation that drives a desire to scratch, a behavior observed in many animals. Although generally short-lasting and not causing harm, there are several pathological conditions where chronic itch is a hallmark symptom and in which prolonged scratching can induce damage. Finding medications to counteract the sensation of chronic itch has proven difficult due to the molecular complexity that involves a multitude of triggers, receptors and signaling pathways between skin, immune and nerve cells. While much has been learned about pruritus from in vivo animal models, they have limitations that corroborate the necessity for a transition to more human disease-like models. Also, reducing animal use should be encouraged in research. However, conducting human in vivo experiments can also be ethically challenging. Thus, there is a clear need for surrogate models to be used in pre-clinical investigation of the mechanisms of itch. Most in vitro models used for itch research focus on the use of known pruritogens. For this, sensory neurons and different types of skin and/or immune cells are stimulated in 2D or 3D co-culture, and factors such as neurotransmitter or cytokine release can be measured. There are however limitations of such simplistic in vitro models. For example, not all naturally occurring cell types are present and there is also no connection to the itch-sensing organ, the central nervous system (CNS). Nevertheless, in vitro models offer a chance to investigate otherwise inaccessible specific cell–cell interactions and molecular pathways. In recent years, stem cell-based approaches and human primary cells have emerged as viable alternatives to standard cell lines or animal tissue. As in vitro models have increased in their complexity, further opportunities for more elaborated means of investigating itch have been developed. In this review, we introduce the latest concepts of itch and discuss the advantages and limitations of current in vitro models, which provide valuable contributions to pruritus research and might help to meet the unmet clinical need for more refined anti-pruritic substances.

Modulation of the kappa and mu opioid axis for the treatment of chronic pruritus: A review of basic science and clinical implications

Introduction

Treating chronic pruritus is challenging for dermatologists due to the lack of therapeutic options. We review the effects of κ-opioid receptor (KOR) and μ-opioid receptor (MOR) in the modulation of itch, summarize evidence supporting the efficacy and safety of opioid receptor–targeting agents in chronic pruritus, and address clinical considerations.

Results

Preclinical studies have found neural pathways underlying detection, transmission, and modulation of itch signaling and spotlighted the importance of neuronal KOR and MOR in itch perception. Clinical reports suggest that opioid axis modulation may be the basis for the successful treatment of chronic itch. Several agents (MOR antagonist naltrexone; KOR agonists nalfurafine and difelikefalin; dual-acting KOR agonists/MOR antagonists butorphanol and nalbuphine) have been evaluated for treating chronic pruritus in case series, small studies, and clinical trials; nalbuphine has progressed through preliminary (phase II/III) studies in uremic pruritus and prurigo nodularis. The antipruritic efficacy of these agents has been observed across multiple disorders with disparate etiologies, suggesting the potential utility of this class to provide a unified approach to chronic pruritus treatment.

Conclusions

The relative safety of these agents, including a reduced potential for dependence versus MOR-agonist analgesics, should help overcome resistance to the use of opioid receptor–targeting agents in chronic pruritus treatment.

Risk of Hematologic Cancer in Patients With Undifferentiated Pruritus

Importance

Although pruritus is common in patients with hematologic cancers, it is unknown whether patients with undifferentiated pruritus have higher risk of developing hematologic cancer. Furthermore, it is unclear whether serum lactate dehydrogenase (LDH) level, commonly ordered for cancer workup, has diagnostic utility in patients with pruritus.

Objective

To assess the risk of hematologic cancer and the diagnostic utility of LDH level in patients with undifferentiated pruritus.

Design, Setting, and Participants

This retrospective population-level cohort analysis was conducted using the TriNetX Research Network, a global health records database encompassing more than 69 million patients, from 2002 to 2020. The study included 327 502 eligible patients diagnosed with unspecified pruritus, excluding those with existing chronic pruritic dermatoses or systemic diseases known to cause pruritus, along with 327 502 matched controls.

Exposures

Development of hematologic cancer within 1 year, 5 years, and 10 years following unspecified pruritus diagnosis.

Main Outcomes and Measures

Primary study outcomes were 1-year, 5-year, and 10-year relative risks (RRs) for development of 9 hematologic cancers in patients with pruritus compared with control patients. Secondary outcomes were 1-year, 5-year, and 10-year RRs for any hematologic cancer at different LDH cutoffs (250 U/L and 500 U/L).

Results

After matching, the pruritus and control cohorts each had 327 502 patients (68.1% female patients; 0.4% American Indian or Alaska Native patients; 3.5% Asian patients; 22.2% Black patients; 0.1% Native Hawaiian or Pacific Islander patients; 59.3% White patients; mean [SD] age, 42.2 [22] years). Patients with pruritus had increased 1-year risk of Hodgkin lymphoma (RR, 4.42; 95% CI, 2.83-6.88), myeloid leukemia (RR, 2.56; 95% CI, 1.79-3.67), multiple myeloma (RR, 2.38; 95% CI, 1.66-3.41), non-Hodgkin lymphoma (RR, 2.35; 95% CI, 1.96-2.82), monoclonal gammopathy (RR, 1.90; 95% CI, 1.55-2.32), myelodysplastic syndrome (RR, 1.74; 95% CI, 1.14-2.64), and lymphocytic leukemia (RR, 1.47; 95% CI, 1.07-2.02). After 12 months, the cancer risk was comparable with that of controls. Patients with pruritus had increased LDH levels, which were not associated with increased hematologic cancer risk.

Conclusions and Relevance

In this cohort study, the RR of hematologic cancer in patients with undifferentiated pruritus was highest in the first 12 months, and LDH level had limited diagnostic utility in these patients. Clinicians should consider a thorough review of symptoms and assessment of cancer risk factors when deciding on workup for patients presenting with undifferentiated pruritus.

Molecular and cellular mechanisms of itch and pain in atopic dermatitis and implications for novel therapeutics

Atopic dermatitis is a chronic inflammatory skin disease. Patients with atopic dermatitis experience inflammatory lesions associated with intense itch and pain, which lead to sleep disturbance and poor mental health and quality of life. We review the molecular mechanisms underlying itch and pain symptoms in atopic dermatitis and discuss the current clinical development of treatments for moderate‐to‐severe atopic dermatitis. The molecular pathology of atopic dermatitis includes aberrant immune activation involving significant cross‐talk among the skin and immune and neuronal cells. Exogenous and endogenous triggers modulate stimulation of mediators including cytokine/chemokine expression/release by the skin and immune cells, which causes inflammation, skin barrier disruption, activation and growth of sensory neurons, itch and pain. These complex interactions among cell types are mediated primarily by cytokines, but also involve chemokines, neurotransmitters, lipids, proteases, antimicrobial peptides, agonists of ion channels or various G protein–coupled receptors. Patients with atopic dermatitis have a cytokine profile characterised by abnormal levels of interleukins 4, 12, 13, 18, 22, 31 and 33; thymic stromal lymphopoietin; and interferon gamma. Cytokine receptors mainly signal through the Janus kinase/signal transducer and activator of transcription pathway. Among emerging novel therapeutics, several Janus kinase inhibitors are being developed for topical or systemic treatment of moderate‐to‐severe atopic dermatitis because of their potential to modulate cytokine expression and release. Janus kinase inhibitors lead to changes in gene expression that have favourable effects on local and systemic cytokine release, and probably other mediators, thus successfully modulating molecular mechanisms responsible for itch and pain in atopic dermatitis.

Acupuncture for the Treatment of Itch: Peripheral and Central Mechanisms

Despite the widespread clinical use of acupuncture in the treatment of pruritus caused by psoriasis, urticaria, uremic, and other diseases, insights into the mechanism of action of acupuncture are still emerging. For the above reasons, a beneficial effect of acupuncture on pruritus was not recommended or reported in recent clinical practice guidelines. Acupuncture is a kind of physical stimulation, which has the characteristics of multi-channel and multi-target effects. The biomechanical stimulation signal of acupuncture needling can be transformed into bioelectric and chemical signals; interfere with kinds of cells and nerve fibers in the skin and muscle; alter signaling pathways and transcriptional activity of cells, mediators, and receptors; and result in inhibition of peripheral and central transmission of pruritus. Available mechanistic data give insights into the biological regulation potency of acupuncture for pruritus and provide a basis for more in-depth and comprehensive mechanism research.

Itch: Epidemiology, clinical presentation, and diagnostic workup

Itch, or pruritus, is the uncomfortable sensation underlying the desire to scratch. Itch is a very common complaint in the general population that can result from dermatologic, systemic (eg, renal, hepatobiliary, endocrine), paraneoplastic, neuropathic, and psychogenic etiologies. Chronic itch is associated with significant sleep disturbances and profoundly reduces overall quality of life. Certain populations, including elderly and African Americans, are at increased risk of experiencing heightened burden of itch. Because of the variable clinical presentation and wide-ranging etiologies, itch presents a challenge for clinicians. The initial evaluation should include a complete blood count, with differential, hepatic, renal, and thyroid function testing along with diabetes screening. Further testing should be guided by history and physical examination findings. There should be a heightened concern for underlying malignancy in individuals older than 60 years of age who have a history of liver disease and diffuse itch less than 12 months of duration. For individuals with chronic pruritus of unknown origin, increased blood eosinophils may serve as a biomarker of T helper cell type 2 polarization and response to immunomodulator therapies. In this first part of a 2-part continuing medical education series, we describe the broader epidemiology and specific conditions associated with itch and the clinical presentation and diagnostic workup for patients with itch.

Epidemiology, Comorbidities, and Prescription Patterns of Korean Prurigo Nodularis Patients: A Multi-Institution Study

Prurigo nodularis (PN) is a chronic dermatosis typified by extraordinarily itchy nodules. However, little is known of the nature and extent of PN in Asian people. This study aimed to describe the epidemiology, comorbidities, and prescription pattern of PN in Koreans based on a large dermatology outpatient cohort. Patients with PN were identified from the Catholic Medical Center (CMC) clinical data warehouse. Anonymized data on age, sex, diagnostic codes, prescriptions, visitation dates, and other relevant parameters were collected. Pearson correlation analysis was used to calculate the correlation between PN prevalence and patient age. Conditional logistic regression modeling was adopted to measure the comorbidity risk of PN. A total of 3591 patients with PN were identified at the Catholic Medical Center Health System dermatology outpatient clinic in the period 2007–2020. A comparison of the study patients with age- and sex-matched controls (dermatology outpatients without PN) indicated that PN was associated with various comorbidities including chronic kidney disease (adjusted odds ratio (aOR), 1.48; 95% confidence interval (CI), 1.29–1.70), dyslipidemia (aOR, 1.88; 95% CI, 1.56–2.27), type 2 diabetes mellitus (aOR, 1.37; 95% CI, 1.22–1.54), arterial hypertension (aOR, 1.50; 95% CI, 1.30–1.73), autoimmune thyroiditis (aOR, 2.43; 95% CI, 1.42–4.16), non-Hodgkin’s lymphoma (aOR, 1.95; 95% CI, 1.23–3.07), and atopic dermatitis (aOR, 2.16, 95% CI, 1.91–2.45). Regarding prescription patterns, topical steroids were most favored, followed by topical calcineurin inhibitors; oral antihistamines were the most preferred systemic agent for PN. PN is a relatively rare but significant disease among Korean dermatology outpatients with a high comorbidity burden compared to dermatology outpatients without PN. There is great need for breakthroughs in PN treatment.

Health-Related Quality of Life Measurement in Public Health

Patient-reported outcomes are recognized as essential for the evaluation of medical and public health interventions. Over the last 50 years, health-related quality of life (HRQoL) research has grown exponentially from 0 to more than 17,000 papers published annually. We provide an overview of generic HRQoL measures used widely in epidemiological studies, health services research, population studies, and randomized clinical trials [e.g., Medical Outcomes Study SF-36 and the Patient-Reported Outcomes Measurement Information System (PROMIS^®)-29]. In addition, we review methods used for economic analysis and calculation of the quality-adjusted life year (QALY). These include the EQ-5D, the Health Utilities Index (HUI), the self-administered Quality of Well-being Scale (QWB-SA), and the Health and Activities Limitation Index (HALex). Furthermore, we consider hybrid measures such as the SF-6D and the PROMIS-Preference (PROPr). The plethora of HRQoL measures has impeded cumulative science because incomparable measures have been used in different studies. Linking among different measures and consensus on standard HRQoL measurement should now be prioritized. In addition, enabling widespread access to common measures is necessary to accelerate future progress. Expected final online publication date for the Annual Review of Public Health, Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

A New Era with the Development of Cytokine-Based Therapy for Pruritus

Pruritus is a common dermatological condition and negatively impacts QOL. Persistent pruritus and excessive scratching behavior can lead to the itch-scratch cycle that exacerbates inflammatory skin diseases. Conventional antipruritic drugs, such as antihistamines, corticosteroids, or anticonvulsants, are sometimes insufficient. Recently, however, molecularly targeted drugs, such as IL-31 or IL-4 receptor-targeting antibodies, have become available or are under clinical trials, dramatically changing the clinical situation. In fact, some of these drugs can improve pruritus without the need for topical steroids. Taken together, these observations point to the importance of cytokine-mediated pruritus, further understanding of which may guide improved therapies.

Real-world comorbidities of atopic dermatitis in the U.S. adult ambulatory population

BACKGROUND

Atopic dermatitis (AD) is a pruritic inflammatory skin disease associated with various comorbidities. However, comprehensive analyses of real-world comorbidities in adult AD patients are limited.

OBJECTIVE

To characterize the real-world comorbidities associated with adult AD in an ambulatory population.

METHODS

We queried the MarketScan Commercial Claims and Encounters database from January 1, 2017 to December 31, 2017. Multivariable logistic regressions were performed to compare comorbidities in adult AD patients vs. age- and sex-matched controls.

RESULTS

A total of 39,779 AD patients and 353,743 controls were identified. Increased odds of psychiatric conditions including anxiety (OR 1.44) and mood disorders (OR 1.31) were observed in AD. AD patients had higher likelihood of autoimmune diseases including vitiligo (OR 4.44) and alopecia areata (OR 6.01). Adult AD was also associated with infections including impetigo (OR 9.72), MRSA (OR 3.92), and cellulitis (OR 2.52). AD patients were more likely to have systemic conditions including lymphoid/hematopoietic malignancy (OR 1.91), atherosclerosis (OR 1.69), and metabolic syndrome (OR 1.47). For all the above, p<0.001.

LIMITATIONS

Retrospective analysis of healthcare claims data CONCLUSIONS: Adult AD is associated with various psychiatric and systemic comorbidities, emphasizing the systemic nature of AD and the need for collaborative management of these patients.

Approach to the Patient with Chronic Pruritus

Chronic pruritus (itch lasting ≥6 weeks) is a bothersome chief complaint that may present in a broad variety of diseases. Most itch-causing diagnoses fit into 1 of 5 categories (inflammatory, secondary to systemic disease, neuropathic, chronic pruritus of undetermined origin, and psychogenic itch) and this broad differential can be narrowed using key findings in the history and physical. In this article, we discuss which key findings are most pertinent for narrowing this differential and guiding further workup and treatment, as well as how to treat many itchy conditions.

Psychocutaneous Medicine Clinic: Wisconsin Experience

BACKGROUND

Psychocutaneous medicine, also known as psychodermatology, is a subspecialty of dermatology and psychiatry that explores the interactions between the skin and the brain. For many patients, skin disease affects their quality of life and mental well-being. For others, psychiatric problems exhibit skin signs.

OBJECTIVE

Little data are available from psychocutaneous clinics worldwide. The aim of our review is to advance clinical knowledge about psychocutaneous medicine and help bridge the current gap between dermatology and psychiatry.

METHODS

A total of 808 cases referred to our psychocutaneous clinic from 2002 to 2018 were reviewed. A specific code in the electronic health records allowed us to identify these patients. All the patients referred to the clinic were included in the study. The primary variable of interest was the patient's final diagnosis, as made by the psychiatrist. Patient demographics (age, sex, marital status), number of visits, and treatments were collected.

RESULTS

Our data showed a high prevalence of skin picking disorder followed by depressive and anxiety disorders. Serious mental health disorders such as major depressive disorder and generalized anxiety disorder were common in our patients. Three-fourth of our patients were women. Skin picking was more prevalent in women, and alcohol dependence was more prevalent in men. No other significant gender differences in final diagnoses were found. 44.2% of patients needed one visit and were able to return to referring physicians for follow up.

CONCLUSION

This is the largest collection of patients from a psychocutaneous clinic in the literature to date. Previous studies show that psychocutaneous clinics save health care dollars by decreasing the number of patient visits and improving the quality of life of patients with dermatologic problems. Introducing the results of this clinic could inform future integration of psychocutaneous clinics in dermatology practices and identify areas of need in training dermatology and psychiatry residents.

Interleukin-31 and Pruritic Skin

Skin inflammation often evokes pruritus, which is the major subjective symptom in many inflammatory skin diseases such as atopic dermatitis and prurigo nodularis. Pruritus or itch is a specific sensation found only in the skin. Recent studies have stressed the pivotal role played by interleukin-31 (IL-31) in the sensation of pruritus. IL-31 is produced by various cells including T helper 2 cells, macrophages, dendritic cells and eosinophils. IL-31 signals via a heterodimeric receptor composed of IL-31 receptor A (IL-31RA) and oncostatin M receptor β. Recent clinical trials have shown that the anti-IL-31RA antibody nemolizumab can successfully decrease pruritus in patients with atopic dermatitis and prurigo nodularis. The IL-31 pathway and pruritic skin are highlighted in this review article.

IL-31 Inhibition as a Therapeutic Approach for the Management of Chronic Pruritic Dermatoses

Chronic pruritus is a debilitating symptom with limited treatment options. Identifying molecular targets underlying chronic pruritic dermatoses is essential for the development of novel, targeted therapies. IL-31 is an important mediator of itch by integrating dermatologic, neural, and immune systems. IL-31 helps induce and maintain chronic pruritus via both indirect stimulation of inflammatory cells and through direct neural sensitization. IL-31 is overexpressed in various chronic pruritic skin conditions, and exogenous IL-31 induces itch and scratching behavior. Studies have demonstrated that IL-31R and IL-31 antagonism significantly reduces itch in patients with atopic dermatitis and prurigo nodularis, two extremely pruritic skin conditions. Emerging evidence, including recent phase II clinical trials of IL-31R antagonists, demonstrates that IL-31 plays an important role in itch signaling. Additional studies are ongoing to evaluate IL-31R and IL-31 antagonism as treatments of chronic pruritus.

Association of prurigo nodularis and infectious disease hospitalizations: a national cross-sectional study

BACKGROUND

Prurigo nodularis (PN) is associated with a variety of systemic comorbidities, including infectious diseases such as HIV and viral hepatitis. There are limited data on other infectious disease comorbidities in patients with PN.

AIM

To characterize infectious disease hospitalizations among patients with PN and the associated cost burden.

METHODS

We searched the 2016-2017 National Inpatient Sample, a cross-sectional sample of 20% of all US hospitalizations, for infectious disease hospitalizations among patients with PN. Associations of PN with infections and related costs were determined using multivariable logistic and linear regression, adjusting for age, race, sex and insurance type.

RESULTS

PN was associated with any infection overall (OR = 2.98, 95% CI 2.49-3.56), and with HIV, cutaneous, hepatobiliary, central nervous system, bacterial, viral and fungal/parasitic infections and for sepsis. Patients with PN had a higher mean cost of care (US$11 667 vs. US$8893, P < 0.001) and length of stay (5.5 vs. 4.2 days, P < 0.001) for any infection overall and for 7 of 13 other infections. Adjusting for age, race, sex and insurance coverage, PN was associated with higher cost (+30%, 95% CI +17 to +44%) and higher length of stay (+30%, 95% CI +18 to +44%) for any infection overall, and for several specific infections. These associations remained with alternate regression models adjusting for severity of illness.

CONCLUSION

There is a high infectious disease burden among patients with PN, corresponding to higher healthcare utilization and spending. Clinicians must be aware of these associations when treating these patients with immunomodulatory drugs.

Interleukin-31 as a Clinical Target for Pruritus Treatment

In recent years, the published literature has suggested the key involvement of the cytokine interleukin-31 (IL-31) in the symptomatology of pruritus, and both IL-31 and its receptor have become potential therapeutic targets for a range of pruritic diseases. Elevated levels of IL-31 or its receptor have been reported in the tissue or serum of patients with pruritic skin diseases, such as atopic dermatitis, prurigo nodularis, and psoriasis. Pruritus places a heavy burden on patients, and can have a negative impact on daily life, sleep, and mental health. Since current anti-pruritic treatments are often ineffective, affected patients are in urgent need of new therapies. As a result, drug development targeting the IL-31 pathway is evolving rapidly. To date, only nemolizumab, a humanized monoclonal antibody targeting the IL-31 receptor, has successfully completed late-stage clinical studies. This article will highlight our current clinical understanding of the role of IL-31 in pruritic disease, and explore recent progress in drug development as well as the anticipated future advances in this field.