Rationale-Heterogeneity in asthma expression is multidimensional, including variability in clinical, physiologic, and pathologic parameters. Classification requires consideration of these disparate domains in a unified model.Objectives-To explore the application of a multivariate mathematical technique, k-means cluster analysis, for identifying distinct phenotypic groups.Methods-We performed k-means cluster analysis in three independent asthma populations. Clusters of a population managed in primary care (n = 184) with predominantly mild to moderate disease, were compared with a refractory asthma population managed in secondary care (n = 187). We then compared differences in asthma outcomes (exacerbation frequency and change in corticosteroid dose at 12 mo) between clusters in a third population of 68 subjects with predominantly refractory asthma, clustered at entry into a randomized trial comparing a strategy of minimizing eosinophilic inflammation (inflammation-guided strategy) with standard care.Measurements and Main Results-Two clusters (early-onset atopic and obese, noneosinophilic) were common to both asthma populations. Two clusters characterized by marked discordance between symptom expression and eosinophilic airway inflammation (early-onset symptom predominant and late-onset inflammation predominant) were specific to refractoryCorrespondence and requests for reprints should be addressed to Dr. P. Haldar, M.R.C.P., Institute for Lung Health, Glenfield Hospital, Leicester, LE3 9QP, UK. ph62@le.ac.uk. Conflict of Interest Statement: P.H. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. I.D.P. received $2,000 for speaking at conferences organized by GlaxoSmithKline and $5,000 for speaking at conferences organized by AstraZeneca; he is in receipt of a $500,000 grant for a study of severe asthma from GlaxoSmithKline. D.E.S. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. M.A.B. has received lecture fees and conference support from AstraZeneca and GlaxoSmithKline. M.T. has received speaker's honoraria in the last 3 years for speaking at meetings sponsored by the following companies marketing respiratory products: AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, MSD, Schering-Plough, Teva; he has received honoraria for attending advisory panels with Altana, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, MSD, Merck Respiratory, Schering-Plough, Teva; he has received sponsorships to attend international scientific meetings from GlaxoSmithKline, MSD, AstraZeneca; he has received funding for research projects from GlaxoSmithKline, MSD, AstraZeneca; he holds a research fellowship from Asthma UK. C.E.B. has received a total of $2.2 million in research funding over the last 3 years (or is pending) from AstraZeneca, Cambridge Antibody Technology, GlaxoSmithKline; he has received less than $10,000 per annum from consultancy fees from Cambridge Antibody Technology...

BACKGROUND-Exacerbations of asthma are associated with substantial morbidity and mortality and with considerable use of health care resources. Preventing exacerbations remains an important goal of therapy. There is evidence that eosinophilic inflammation of the airway is associated with the risk of exacerbations.

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The infiltration of airway smooth muscle by mast cells is associated with the disordered airway function found in asthma.

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Background: The debate as to whether asthma is a single or heterogeneous disease remains unresolved although pathological studies, mostly using fibreoptic bronchoscopy on small numbers of subjects, have emphasised the similarities between different clinical phenotypes. Methods: Lower airway inflammation was assessed non-invasively using induced sputum in 34 normal controls and 259 adults with symptomatic asthma receiving treatment at steps 1-3 of the British Thoracic Society (BTS) guidelines. A subgroup of 49 patients treated with as required β 2 agonists only who met BTS criteria for a step up in treatment were studied before and 2 months after treatment with inhaled budesonide 400 µg twice daily. Results: There was considerable heterogeneity in induced sputum cell counts, particularly in non-atopic patients. A subgroup of 60 patients had a distinctive sputum cell profile with a neutrophil count higher than our normal range (>65.3%) and a normal sputum eosinophil count (<1.9%). These patients were older, predominantly female, and were more likely to be non-atopic but otherwise had similar clinical and physiological features to the group as a whole. Among the 49 subjects studied before and after inhaled budesonide, 11 patients had an isolated sputum neutrophilia. Following treatment, these patients showed significantly less improvement in visual analogue symptom scores (-5.5 v -19.4 mm; mean difference 13.9; 95% CI 0.7 to 27.0), forced expiratory volume in 1 second (FEV 1 ) (-0.08 v 0.13 l; mean difference 0.21; 95% CI 0.03 to 0.39), and concentration of methacholine provoking a fall in FEV 1 of 20% or more (PC 20 ) (0.15 v 1.29 doubling doses; mean difference 1.11; 95% CI 0.13 to 2.15) than the remaining 38 patients. Conclusions: These results suggest the presence of a distinct subgroup of patients with mild to moderate asthma who have predominantly neutrophilic airway inflammation and who respond less well to treatment with inhaled corticosteroids.

Background-Hypereosinophilic syndromes (HES) are a heterogeneous group of rare disorders defined by persistent blood eosinophilia ≥1.5 × 10 9 /L, absence of a secondary cause, and evidence of eosinophil-associated pathology. With the exception of a recent multicenter trial of mepolizumab

Patients with refractory asthma have evidence of up-regulation of the TNF-alpha axis. (ClinicalTrials.gov number, NCT00276029.).