Eosinophil count testing in patients with asthma varies by healthcare provider type in the US: a retrospective study

Patients with asthma with an eosinophilic phenotype may be eligible for additional treatment options to improve disease control; however, the prevalence and frequency of eosinophil testing is unknown. This study assessed blood eosinophil count testing prevalence in patients with asthma by exacerbation frequency and healthcare provider (HCP) type.

This was a retrospective, longitudinal, real-world study (GSK ID: 214470) utilizing the Merative Explorys^® Universe electronic health records database. Eligible patients had ≥ 2 asthma diagnostic codes (January 2016-December 2018) (Index date: first asthma diagnosis). Outcomes included patient demographics and clinical characteristics (12 months pre-index [baseline]), and prevalence of blood eosinophil count testing, stratified by exacerbation frequency (infrequent exacerbations [< 2]) or frequent exacerbations [≥ 2] or primary HCP (Allergist/Pulmonologist, a primary care physician [PCP] or other HCP) during the 12 months post-index (follow-up).

Of 400,254 patients included (mean age: 51.2 years; 70.8% female), the most common provider type at baseline was a PCP (76.8%). A higher proportion of patients with frequent exacerbations had blood eosinophil count tests at baseline (55.4-69.5%) and follow-up (67.9-75.1%), compared with patients with infrequent exacerbations (55.5-63.7%, 62.4-67.3%). Significantly more patients in the Allergist/Pulmonologist subgroup had ≥ 1 blood eosinophil count test result compared with patients in the PCP subgroup at both baseline (59.9% vs. 50.7%; p < 0.001) and follow-up (59.0% vs. 56.2%; p < 0.001). In the total population, the mean (SD) number of tests ordered was 3.4 (5.3) and 4.1 (6.4) during the baseline and follow-up periods, respectively. A greater mean number of tests were ordered for patients with frequent exacerbations, most apparently in the Allergist/Pulmonologist subgroup during baseline and follow-up (7.4 vs. 4.9). For patients with frequent exacerbations and blood eosinophil count test results, the mean (SD) number of tests ranged from 3.1 (4.6) to 5.8 (8.3) at baseline and 5.1 (8.5) to 7.4 (10.6) during follow-up.

The prevalence of blood eosinophil count testing in patients with asthma remains suboptimal. Routine blood eosinophil count testing should be considered by HCPs for patients with asthma to increase identification of the eosinophilic asthma phenotype, which may inform the decision to advance to targeted biologic therapy.