Asthma phenotyping in primary care: applying the International Severe Asthma Registry eosinophil phenotype algorithm across all asthma severities.

Marjan Kerkhof, Trung N Tran, Riyad Alleheb, G Walter Canonica, Liam G Heaney, Mark Hew, Luis Perez de Llano, Michael E Wechsler, Lakmini Bulathsinhala, Victoria A. Carter, Isha Chaudhry, Neva Eleangovan, Ruth B Murray, Chris A. Price, David B. Price* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Background: An eosinophil phenotype gradient algorithm has been developed and applied to a large severe asthma cohort (International Severe Asthma Registry; ISAR).

Objective: We sought to re-apply this algorithm in a UK primary care asthma cohort, quantify the eosinophilic phenotype and, assess the relationship between likelihood of eosinophilic phenotype and asthma severity/healthcare resource utilization (HCRU).

Methods: Patients (≥13 years old) with active asthma and ≥1 blood eosinophil count included from the Optimum Patient Care Research Database and the Clinical Practice Research Datalink, were categorized according to the likelihood of eosinophilic phenotype using the ISAR gradient eosinophilic algorithm. Patient demographic, clinical and HCRU characteristics were described for each phenotype.

Results: Of 241,006 patients, 50.3%, 22.2% and 21.9% “most likely” (Grade 3), “likely” (Grade 2), and “least likely” (Grade 1) had an eosinophilic phenotype respectively, and 5.6% had a non-eosinophilic phenotype (Grade 0). Compared to patients with non-eosinophilic asthma, those “most likely” to have an eosinophilic phenotype tended to have more co-morbidities (% with Charlson co-morbidity index ≥2: 28.2% vs 6.9%) and experienced more asthma attacks (% with ≥1 attack: 24.8% vs 15.3%). These patients were also more likely to have difficult-to-treat asthma (31.1% vs 18.3%), receive more intensive treatment (% on GINA (2020) Step 4 or 5: 44.2% vs 27.5%), and greater HCRU (e.g. 10.8 vs 7.9 GP all-cause consultations/year).

Conclusion: The eosinophilic asthma phenotype predominates in primary care and is associated with greater asthma severity and HCRU. These patients may benefit from earlier and targeted asthma therapy.
Original languageEnglish
Pages (from-to)4353-4370
Number of pages18
JournalThe Journal of Allergy and Clinical Immunology: In Practice
Issue number12
Early online date14 Aug 2021
Publication statusPublished - 1 Dec 2021


  • asthma
  • eosinophilic
  • healthcare resource utilization
  • ISAR
  • phenotypes
  • Primary care
  • severity
  • UK


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