Research Techniques Made Simple: Itch Measurement in Clinical Trials

Mouse Models of Itch

Murine models are vital preclinical and biological tools for studying itch. In this paper, we explore how these models have enhanced our understanding of the mechanisms underlying itch through both acute and chronic itch models. We provide detailed protocols and recommend experimental setups for specific models to guide researchers in conducting itch research. We distinguish between what constitutes a bona fide pruritogen versus a stimulus that causes pruritogen release, an acute itch model versus a chronic itch model, and how murine models can capture aspects of pruritus in human disease. Finally, we highlight how mouse models of itch have transformed our understanding and development of therapeutics for chronic pruritus in patients.

Treatment of post-burn pruritus - A systematic review and meta-analysis

BACKGROUND

Post-burn pruritus is one of the most common complaints reported by patients with limited evidence for a gold-standard treatment.

OBJECTIVE

To review the literature and assess the efficacy of various interventions in treating post-burn pruritus.

METHODS

PubMed, MEDLINE, CINAHL, Web of Sciences, Ovid Databases, and ClinicalTrials.Gov were searched. The articles were scored by two assessors for inclusion with a third independent assessor resolving conflicting scores.

RESULTS

The present systematic review and meta-analysis synthesised findings from a total of nine studies, representing a pool of 323 patients. The standardized mean effect size for the various categories of interventions was: naltrexone at 1.47 (95 % CI of 0.75-2.20, p < 0.0000), coverings at 0.94 (95 % CI of 0.40-1.48, p = 0.006), topical ozonated oil at 2.64 (95 % CI of 1.94-3.34, p < 0.00001), lasers at 2.34 (95 % CI of 1.60-3.09, p < 0.00001), current stimulation at 1.03 (95 % CI of -0.04 to 2.10, p = 0.06), and lemon balm tea at 0.54 (95% CI of 0.12-0.96, p = 0.01).

CONCLUSIONS

Current evidence suggests that current modalities have a statistically significant, but not clinically significant, reduction in pruritus. This review highlights the limited quality of evidence in the literature and the poor quality of reporting among excluded studies.

Which Clinical Measurement Tools for Atopic Dermatitis Severity Make the Most Sense in Clinical Practice?

Assessment of atopic dermatitis (AD) severity is essential for therapeutic decision making and monitoring treatment progress. However, there are a myriad of clinical measurement tools available, some of which are impractical for routine clinical use despite being recommended for clinical trials in AD. For measurement tools to be used in clinical practice, they should be valid, reliable, rapidly completed, and scored, and easily incorporated into existing clinic workflows. This narrative review addresses content, validity, and feasibility, and provides a simplified repertoire of assessments for clinical assessment of AD based on prior evidence and expert opinion. Tools that may be feasible for clinical practice include patient-reported outcomes (eg, dermatology life quality index, patient-oriented eczema measure, numerical rating scales for itch, pain, and sleep disturbance, AD Control Tool, and patient-reported global assessment), and clinician-reported outcomes (eg, body surface area and investigator's global assessment). AD is associated with variable clinical signs, symptoms, extent of lesions, longitudinal course, comorbidities, and impacts. Any single domain is insufficient to holistically characterize AD severity, select therapy, or monitor treatment response. A combination of these tools is recommended to balance completeness and feasibility.

A multimodal sensing ring for quantification of scratch intensity

BACKGROUND

An objective measurement of chronic itch is necessary for improvements in patient care for numerous medical conditions. While wearables have shown promise for scratch detection, they are currently unable to estimate scratch intensity, preventing a comprehensive understanding of the effect of itch on an individual.

METHODS

In this work, we present a framework for the estimation of scratch intensity in addition to the detection of scratch. This is accomplished with a multimodal ring device, consisting of an accelerometer and a contact microphone, a pressure-sensitive tablet for capturing ground truth intensity values, and machine learning algorithms for regression of scratch intensity on a 0-600 milliwatts (mW) power scale that can be mapped to a 0-10 continuous scale.

RESULTS

We evaluate the performance of our algorithms on 20 individuals using leave one subject out cross-validation and using data from 14 additional participants, we show that our algorithms achieve clinically-relevant discrimination of scratching intensity levels. By doing so, our device enables the quantification of the substantial variations in the interpretation of the 0-10 scale frequently utilized in patient self-reported clinical assessments.

CONCLUSIONS

This work demonstrates that a finger-worn device can provide multidimensional, objective, real-time measures for the action of scratching.

Seborrheic dermatitis: topical therapeutics and formulation design

Seborrheic dermatitis (SD) is a common dermatological disorder with symptoms that include skin flaking, erythema and pruritus. This review discusses the topical products available for treating SD, which target several aspects of disease pathobiology, including cutaneous microbial dysbiosis (driven by Malassezia yeast), inflammation, sebum production and skin barrier disruption. Among the various treatments available, zinc pyrithione (ZnPT) based products that exhibit anti-fungal action are the market leaders. A skin compartment approach is presented here for combining ZnPT exposure information with threshold levels for anti-fungal efficacy and toxicity, overall providing a comprehensive picture of ZnPT therapeutics and safety. While Malassezia yeast on the surface are effectively targeted, yeast residing beyond the superficial follicle may not receive adequate ZnPT for anti-fungal effect forming the basis for skin re-colonisation. Levels entering systemic circulation from topical delivery are well below toxic thresholds, however the elevated zinc levels within the viable epidermis warrants further investigation. Strategies to improve formulation design can be broadly classified as influencing 1) topical delivery, 2) therapeutic bioactivity, 3) skin mildness, and 4) sensory attributes. Successful SD treatment ultimately requires formulations that can balance efficacy, safety, and consumer appeal.

Alteration of Skin Microbiome in CKD Patients Is Associated With Pruritus and Renal Function

Dysbiotic gut microbiome in chronic kidney disease (CKD) patients has been extensively explored in recent years. Skin microbiome plays a crucial role in patients with skin diseases or even systemic disorders. Pruritus is caused by the retention of uremic solutes in the skin. Until now, no studies have investigated the role of skin microbiome in CKD and its association with pruritus. Here, we aim to examine the bacterial profile of skin microbiome in CKD and whether it is correlated to pruritus. A total of 105 CKD patients and 38 healthy controls (HC) were recruited. Skin swab was used to collect skin samples at the antecubital fossa of participants. Bacterial 16S rRNA genes V3–V4 region was sequenced on NovaSeq platform. On the day of skin sample collection, renal function was assessed, and numeric rating scale was used to measure pruritus severity. Principal coordinate analysis (PCoA) revealed a significant difference in bacterial composition between the groups of CKD and HC. A depletion of bacterial diversity was observed in CKD patients. Akkermansia, Albimonas, Escherichia–Shigella, etc. showed significant higher abundance in CKD patients, whereas Flavobacterium, Blastomonas, Lautropia, etc. significantly declined in patients. Escherichia–Shigella achieved an acceptable diagnostic biomarker with area under the curve (AUC) value of 0.784 in the receiver operating characteristics (ROC) curve. In addition, CKD patients with pruritus (P-CKD) had a different bacterial community comparing to those without pruritus (non-P-CKD) and HC group. Several bacterial genera showing significant difference between P-CKD and non-P-CKD/HC, such as Oribacterium, significantly declined in P-CKD patients than that in the HC group, and Methylophaga significantly increased in P-CKD patients compared to that in HC subjects. Escherichia–Shigella was positively associated with the levels of pruritus severity, blood urea nitrogen (BUN), uric acid, and urine protein; Oribacterium was negatively associated with pruritus severity, whereas it was positively associated with estimated glomerular filtration rate (eGFR) and 24-h urine volume. The dysbiotic of skin microbiome in CKD patients and its association with pruritus and renal function shed a light on skin probiotics.

Efficacy of the topical cyclosporine cream assisted by fractional carbon dioxide laser vs topical clobetasol cream for the treatment of plaque psoriasis: Randomized comparative study

BACKGROUND

In mild psoriasis, topical agents remain the mainstay of treatment. However, the available treatments are not satisfactory for a significant proportion of patients in many terms such as efficacy and safety. Because of these deficits, augmentation of therapeutic effect seems desirable.

THIS STUDY AIMS

To evaluate the efficacy of topical cyclosporine cream, delivered by fractional CO₂ laser vs the efficacy of topical clobetasol cream for the treatment of mild to moderate plaque psoriasis.

PATIENTS AND METHODS

Twenty-two patients with chronic plaque psoriasis involving <10% BSA were included in this study. They were randomly allocated into 2 groups. In Group A, patients were instructed to apply cyclosporine cream twice daily for 5 consecutive days per week immediately after fractional carbon dioxide laser session. While in Group B, clobetasol cream was applied twice daily for 5 consecutive days per week until complete clearance or for a maximum of 10 weeks. The efficacy was objectively assisted clinically and by histopathology by using the scores and skin biopsy.

RESULTS

There was a significant improvement of erythema, plaque elevation, and scaling (p < 0.001) with the use of topical cyclosporine cream delivered by the aid of fractional CO₂ laser, compared to base line. However, the improvement was more significant with topical clobetasol cream.

CONCLUSION

Laser-assisted delivery of topical cyclosporine can provide comparable clinical and pathological improvement to that of clobetasol in the psoriatic plaques. These findings were apparent in patients with less widespread disease. However, topical steroid showed more improvement.

Inadequate response and treatment patterns in adults diagnosed with atopic dermatitis and treated with topical therapy

BACKGROUND

Treatment for atopic dermatitis (AD) is complex, particularly in patients with inadequate response to topical therapies. Currently, there is little clinical guidance for the treatment of these patients.

METHODS

A real-world retrospective study utilizing electronic medical records (EMR) and administrative claims data selected patients with AD between January 01 2016 and June 30 2018. Patients had a written prescription for a topical therapy (first observed script = index date) and no prior systemic treatment. Disease severity at index, follow-up treatment response and prescriptions patterns were assessed. A subset of patients linked to claims was evaluated for treatment patterns.

RESULTS

We identified 137,214 adult topical-treated AD patients with no prior systemic therapy. Among the 16,035 patients with available Physician Global Assessment (PGA) at index, 8169 (50.9%) had the moderate-to-severe disease. Among these patients, 60% had an inadequate response to topical therapy. Of 4475 patients linked to claims, 13.0% had claims for systemic therapy during follow-up, most initiated systemic steroids (95.2%), and oral immunosuppressants and biologics were initiated in 3.3% and 3.8%, respectively.

CONCLUSION

In this real-world study, inadequate response to topical therapy among moderate-to-severe AD patients was high and initiation of systemic treatment was low which suggests a need for additional AD-indicated systemic treatment options in this patient population.

A basophil-neuronal axis promotes itch

Itch is an evolutionarily conserved sensation that facilitates expulsion of pathogens and noxious stimuli from the skin. However, in organ failure, cancer, and chronic inflammatory disorders such as atopic dermatitis (AD), itch becomes chronic, intractable, and debilitating. In addition to chronic itch, patients often experience intense acute itch exacerbations. Recent discoveries have unearthed the neuroimmune circuitry of itch, leading to the development of anti-itch treatments. However, mechanisms underlying acute itch exacerbations remain overlooked. Herein, we identify that a large proportion of patients with AD harbor allergen-specific immunoglobulin E (IgE) and exhibit a propensity for acute itch flares. In mice, while allergen-provoked acute itch is mediated by the mast cell-histamine axis in steady state, AD-associated inflammation renders this pathway dispensable. Instead, a previously unrecognized basophil-leukotriene (LT) axis emerges as critical for acute itch flares. By probing fundamental itch mechanisms, our study highlights a basophil-neuronal circuit that may underlie a variety of neuroimmune processes.

Joint AAD-NPF Guidelines of care for the management and treatment of psoriasis with topical therapy and alternative medicine modalities for psoriasis severity measures

Psoriasis is a chronic, inflammatory, multisystem disease that affects up to 3.2% of the United States population. This guideline addresses important clinical questions that arise in psoriasis management and care and provides recommendations based on the available evidence. The treatment of psoriasis with topical agents and with alternative medicine will be reviewed, emphasizing treatment recommendations and the role of dermatologists in monitoring and educating patients regarding benefits as well as risks that may be associated. This guideline will also address the severity assessment methods of psoriasis in adults.

Development and Initial Psychometric Properties of Two Itch-Related Measures: Scratch Intensity and Impact, Sleep-Related Itch and Scratch

Self-report measures are needed to better understand the relationships among sleep, itching, scratching, and chronic itch conditions and their associations with disease severity, QOL, health, and functioning. Two scales related to sleep and/or scratch were recently developed and assessed in 137 patients with chronic itch and atopic dermatitis or psoriasis. The Scratch Intensity and Impact Scale consisted of two factors (scratching intensity and impact of scratching on QOL) that accounted for 64.59% of the variance with a total of 13 items, overall Cronbach's α of 0.93, and test-retest reliability of 0.66. The Sleep-Related Itch and Scratch Scale consisted of one factor that accounted for 63.01% of the variance with a total of 16 items, overall Cronbach's α of 0.98, and test-retest reliability of 0.66. Both measures demonstrated significant correlations with each other as well as other itch-related measures and nonsignificant correlations with scales hypothesized to be unrelated. The final measures demonstrated adequate preliminary psychometric characteristics. It is hoped that these scales will be used for future research and clinical purposes to help fill recognized gaps in understanding about sleep, itch, scratching, atopic dermatitis, and psoriasis.