Predicting Clinical Remission of Chronic Urticaria Using Random Survival Forests: Machine Learning Applied to Real-World Data.

INTRODUCTION: The time required to reach clinical remission varies in patients with chronic urticaria (CU). The objective of this study is to develop a predictive model using a machine learning methodology to predict time to clinical remission for patients with CU. METHODS: Adults with ≥ 2 ICD-9/10 relevant CU diagnosis codes/CU-related treatment > 6 weeks apart were identified in the Optum deidentified electronic health record dataset (January 2007 to June 2019). Clinical remission was defined as ≥ 12 months without CU diagnosis/CU-related treatment. A random survival forest was used to predict time from diagnosis to clinical remission for each patient based on clinical and demographic features available at diagnosis. Model performance was assessed using concordance, which indicates the degree of agreement between observed and predicted time to remission. To characterize clinically relevant groups, features were summarized among cohorts that were defined based on quartiles of predicted time to remission. RESULTS: Among 112,443 patients, 73.5% reached clinical remission, with a median of 336 days from diagnosis. From 1876 initial features, 176 were retained in the final model, which predicted a median of 318 days to remission. The model showed good performance with a concordance of 0.62. Patients with predicted longer time to remission tended to be older with delayed CU diagnosis, and have more comorbidities, more laboratory tests, higher body mass index, and polypharmacy during the 12-month period before the first CU diagnosis. CONCLUSIONS: Applying machine learning to real-world data enabled accurate prediction of time to clinical remission and identified multiple relevant demographic and clinical variables with predictive value. Ongoing work aims to further validate and integrate these findings into clinical applications for CU management.

Clinical Remission of Chronic Spontaneous Urticaria (CSU): A Targeted Literature Review.

INTRODUCTION: Chronic spontaneous (previously known as idiopathic) urticaria (CSU) is a chronic skin disease with the potential for natural remission. The objectives of this targeted literature review were to identify evidence on the clinical course of CSU, including remission rates, and to estimate cumulative remission rates for different time points. METHODS: Electronic databases (MEDLINE, MEDLINE-In Process, Embase, Web of Science, BIOSIS Previews and the Cochrane Library) and relevant conference proceedings were searched to identify studies involving patients with CSU aged ≥ 12 years that provide data on remission rates and disease duration. Observational studies with patient follow-ups of ≥ 1 year or review articles were included. Data extracted from five selected studies were used to run Kaplan-Meier (KM) analyses and best-fit distributions to calculate remission rates per 4-week period and weighted averages. RESULTS: Ten publications were included in this review. The proportion of patients achieving remission within year 1 ranged from 21 to 47%, while reported remission rate estimates at year 5 were 34% and 45%. Based on calculated 4-weekly remission rates, cumulative remission estimates ranged from 9 to 38% at year 1, from 29 to 71% at year 5 and from 52 to 93% at year 20. Cumulative weighted average estimates for the proportion of patients remitting at years 1, 5 and 20 were 17%, 45% and 73%, respectively. CONCLUSIONS: Published evidence suggests that CSU is a self-limiting condition with variable disease severity and duration, apparently dependent on multiple factors. However, data sources differed in terms of definitions of disease severity and remission, as well as in conclusions on influencing factors. Further studies and uniform definitions are required.

Seborrhoeic dermatitis and sebopsoriasis developing in patients on dupilumab: Two case reports.

Cutaneous adverse events to dupilumab can be varied; this necessitates keeping a broad differential diagnosis to identify seemingly paradoxical reactions. It may be possible to treat the adverse event concurrently without stopping dupilumab.

Facial fat necrosis following autologous fat transfer and its management.

Autologous fat transfer (AFT) is an increasingly popular cosmetic procedure practiced by dermatologic surgeons worldwide. As this is an office based procedure performed under local or tumescent anaesthesia with fat transferred within the same individual and limited associated down time its is considered relatively safe and risk free in the cosmetic surgery arena. We describe a case of AFT related fat necrosis causing significant facial dysmorphia and psychosocial distress. We also discuss the benefits and risks of AFT highlighting common causes of fat graft failure.

Autoimmunity and complement in the pathogenesis of chronic urticaria.

Chronic urticaria is a debilitating skin disease that is believed to have an underlying autoimmune etiology in 35% to 50% of cases. Patients with autoimmune urticaria have functional antibodies in their sera that release histamine from basophils and mast cells. The C5a component of complement is required for mast cell degranulation in this process and at least augments basophil histamine release. In this article, the evidence that is key to our understanding of autoimmunity and complement in the pathogenesis of a subset of patients with chronic urticaria is outlined. Some of the issues in testing for and treating autoimmune urticaria are discussed.

Therapeutic potential of macrolide immunosuppressants in dermatology.

Dermatologists are frequently presented with inflammatory dermatoses that are responsive to treatment with immunomodulating drugs. Corticosteroids, particularly when applied topically, have been the mainstay of treatment in the past. Their undoubted efficacy, however, has been undermined by problems with repeated use including tachyphylaxis and side effects such as skin atrophy and hypertension. Macrolide immunosuppressive drugs, originally used for prophylaxis of organ transplant rejection, have been shown to be effective in the treatment of inflammatory dermatoses. The original drugs used in dermatology in this class have their own limitations including poor absorption when used topically and their distinct side-effect profiles. A search for other immunosuppressive macrolide antibiotics has led to the development of new agents, which have enhanced profiles for the treatment of skin disease. This review discusses the main dermatoses that may be targeted by this class of drugs and summarises the topical and systemic macrolides either currently in use, in clinical trials or preclinical development.

The macrolide immunosuppressants in dermatology: mechanisms of action.

Macrolides are xenobiotics, produced by soil fungi, which have immunosuppressant properties. They will probably revolutionise the treatment of inflammatory dermatoses. This article outlines the context and putative mechanisms of action of this novel class of drugs. Cyclosporin, and the structurally distinct macrolides tacrolimus and pimecrolimus (an ascomycin derivative), modulate immune-cell function by inhibiting calcineurin-dependent dephosphorylation-activation of specific nuclear factors, thus preventing transcription of pro-inflammatory cytokines. The macrolide rapamycin (sirolimus) acts by abrogating Target of Rapamycin, a key signalling protein that controls activation of a number of proteins which direct progression of the cell cycle in response to pro-inflammatory cytokines. Tacrolimus and pimecrolimus are small enough molecules to penetrate skin and are available in topical formulations. "Skin-specific" pimecrolimus seems not to cause systemic immunosuppression when given orally. Neither topical tacrolimus nor pimecrolimus are capable of producing skin atrophy. Sirolimus has anti-angiogenic properties that may be beneficial to the treatment of psoriasis and perhaps skin cancer.