Asthma inflammatory phenotypes on four continents: most asthma is non-eosinophilic

WASP Study Group

Research output: Contribution to journalArticle (Academic Journal)peer-review

9 Citations (Scopus)


BACKGROUND: Most studies assessing pathophysiological heterogeneity in asthma have been conducted in high-income countries (HICs), with little known about the prevalence and characteristics of different asthma inflammatory phenotypes in low-and middle-income countries (LMICs). This study assessed sputum inflammatory phenotypes in five centres, in Brazil, Ecuador, Uganda, New Zealand (NZ) and the United Kingdom (UK).

METHODS: We conducted a cross-sectional study of 998 asthmatics and 356 non-asthmatics in 2016-20. All centres studied children and adolescents (age range 8-20 years), except the UK centre which involved 26-27 year-olds. Information was collected using questionnaires, clinical characterization, blood and induced sputum.

RESULTS: Of 623 asthmatics with sputum results, 39% (243) were classified as eosinophilic or mixed granulocytic, i.e. eosinophilic asthma (EA). Adjusted for age and sex, with NZ as baseline, the UK showed similar odds of EA (odds ratio 1.04, 95% confidence interval 0.37-2.94) with lower odds in the LMICs: Brazil (0.73, 0.42-1.27), Ecuador (0.40, 0.24-0.66) and Uganda (0.62, 0.37-1.04). Despite the low prevalence of neutrophilic asthma in most centres, sputum neutrophilia was increased in asthmatics and non-asthmatics in Uganda.

CONCLUSIONS: This is the first time that sputum induction has been used to compare asthma inflammatory phenotypes in HICs and LMICs. Most cases were non-eosinophilic, including in settings where corticosteroid use was low. A lower prevalence of EA was observed in the LMICs than in the HICs. This has major implications for asthma prevention and management, and suggests that novel prevention strategies and therapies specifically targeting non-eosinophilic asthma are required globally.

Original languageEnglish
Pages (from-to)611-623
Number of pages13
JournalInternational Journal of Epidemiology
Issue number2
Early online date30 Aug 2022
Publication statusPublished - 1 Apr 2023

Bibliographical note

Funding Information:
The World ASthma Phenotypes (WASP) collaboration is based on the AsthmaPhenotypes study which is funded by the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 668954. The UK Medical Research Council and Wellcome (grant ref: 21706/Z/19/Z) and the University of Bristol provide core support for ALSPAC. This publication is the work of the authors and L.P and N.P. will serve as guarantors for the contents of this paper. A comprehensive list of grants funding is available on the ALSPAC website []; this research was specifically funded by the ERC grant agreement no 668954 (see above). P.C. was funded by Wellcome Trust, grant number 088862. We would like to thank the participants of this study in all five WASP centres. ALSPAC: we are extremely grateful to all the families who took part in this study, the midwives for their help in recruiting them, and the whole ALSPAC team, which includes interviewers, computer and laboratory technicians, clerical workers, research scientists, volunteers, managers, receptionists and nurses.

Publisher Copyright:
© The Author(s) 2022. Published by Oxford University Press on behalf of the International Epidemiological Association.


  • Humans
  • Cross-Sectional Studies
  • Asthma/epidemiology
  • Phenotype
  • Brazil/epidemiology
  • New Zealand/epidemiology


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