Potential severe asthma hidden in UK primary care

Background: Severe asthma may be under-recognized in primary care.Objective: Identify and quantify patients with potential severe asthma (PSA) in UK primary care, the proportion not referred, and compare primary care PSA patients with confirmed severe asthma patients from UK tertiary care.Methods: Historical cohort study including patients from the Optimum Patient Care Research Database (OPCRD; aged ≥16 years, active asthma diagnosis pre-2014) and UK patients in the International Severe Asthma Registry (UK-ISAR; aged ≥18 years, confirmed severe asthma in tertiarycare). In the OPCRD, PSA was defined as GINA 2018 Step 4 treatment and ≥2 exacerbations/year OR at GINA Step 5. The proportion of these patients and their referral status in the last year was quantified. Demographic and clinical characteristics of groups were compared.Results: Of 207,557 OPCRD patients with asthma, 16,409 (8%) had PSA. Of these, 72% had no referral/specialist review in the past year. Referred PSA patients tended to have greater prevalence of ICS/LABA-add-ons (54.1 vs 39.8%), and experienced significantly (p<0.001) more exacerbations/year (median 3 vs 2/year), worse asthma control and worse lung function (% predicted post-bronchodilator FEV1/FVC 0.69 vs 0.72) versus non-referred patients. Confirmed severe asthmatic patients (i.e. UK161 ISAR) were younger (51 vs 65 years; p<0.001), and significantly (p<0.001) more likely to have uncontrolled asthma (91.4% vs 62.5%), a higher exacerbation rate (4/year [initial assessment] vs 3/year), use ICS/LABA add-ons (67.7% vs 54.1%), and have nasal polyposis (24.2% vs 6.8) than referred PSA patients.Conclusion: Large numbers of patients with PSA in the UK are under-recognized in primary care. These patients would benefit from a more systematic assessment in primary care and possible specialist referral.