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Asthma inflammatory phenotypes on four continents:the World Asthma Phenotypes (WASP) international collaboration

By Lucy Pembrey, Collin Brooks, Harriet Mpairwe, Camila A Figueiredo, Aida Y. Oviedo, Martha Chico, Hajar Ali, Irene Nambuya, Pius Tumwesige, Steven Robertson, Susan Ring, Mauricio L Barreto, Philip J. Cooper, John Henderson, Alvaro A. Cruz, Jeroen Douwes, Neil Pearce, the WASP Study Group

Posted 25 Aug 2020
medRxiv DOI: 10.1101/2020.08.23.20177162

RationaleIn high-income countries less than half of asthma cases involve eosinophilic airways inflammation. Few studies have measured inflammatory asthma phenotypes in low- and-middle-income countries. ObjectivesTo assess asthma inflammatory phenotypes in Brazil, Ecuador, Uganda, New Zealand and the United Kingdom. MethodsWe recruited 998 asthmatics and 356 non-asthmatics: 204/40 in Brazil, 176/67 in Ecuador, 235/132 in New Zealand, 207/50 in Uganda, and 176/67 in the United Kingdom. All centres studied children and adolescents (age-range 8-20 years), except the UK centre involved 26-27 year olds. Information was collected using questionnaires, clinical characterisation, blood, and induced sputum. Measurements and main results87% provided a sputum sample, ranging from 74% (Brazil) to 93% (United Kingdom); of these, 71% were countable. The proportion of asthmatics classified as eosinophilic asthma (EA) was 39% (95% confidence interval 35%-43%) overall: 35% in Brazil, 32% in Ecuador, 50% in New Zealand, 33% in Uganda, and 33% in the United Kingdom. The non-eosinophilic asthmatics (NEA) had similar severity/control to the eosinophilic asthmatics (EA). Of the 61% (95%CI 57%-65%) of cases with NEA, 50% showed no signs of inflammation (paucigranulocytic), with 11% having neutrophilic inflammation. ConclusionsThis is the first time that sputum induction has been used to compare asthma inflammatory phenotypes in high-income countries and low-and-middle-income countries. Most cases were non-eosinophilic. This has major implications for asthma prevention and management in both of these contexts, and supports the need to recognise asthma as a heterogeneous condition, and to develop new prevention strategies and new therapies which target NEA.

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