Potential severe asthma hidden in UK primary care

Background: Severe asthma may be underrecognized 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 patients with PSA with patients with confirmed severe asthma from UK tertiary care. Methods: This was a historical cohort study including patients from the Optimum Patient Care Research Database (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 tertiary care). In the OPCRD, PSA was defined as Global INitiative for Asthma 2018 step 4 treatment and 2 or more exacerbations/y or at Global INitiative for Asthma step 5. The proportion of these patients and their referral status in the last year were quantified. Demographic and clinical characteristics of groups were compared. Results: Of 207,557 Optimum Patient Care Research Database patients with asthma, 16,409 (8%) had PSA. Of these, 72% had no referral/specialist review in the past year. Referred patients with PSA tended to have greater prevalence of inhaled corticosteroid/long-acting β₂-agonist add-ons (54.1 vs 39.8%), and experienced significantly (P < .001) more exacerbations per year (median, 3 vs 2/y), worse asthma control, and worse lung function (% predicted postbronchodilator FEV1/forced vital capacity, 0.69 vs 0.72) versus nonreferred patients. Confirmed patients with severe asthma (ie, UK patients in the International Severe Asthma Registry) were younger (51 vs 65 years; P < .001), and significantly (P < .001) more likely to have uncontrolled asthma (91.4% vs 62.5%), a higher exacerbation rate (4/y [initial assessment] vs 3/y), use inhaled corticosteroid/long-acting β₂-agonist add-ons (67.7% vs 54.1%), and have nasal polyposis (24.2% vs 6.8) than referred patients with PSA. Conclusions: Large numbers of patients with PSA in the United Kingdom are underrecognized in primary care. These patients would benefit from a more systematic assessment in primary care and possible specialist referral.