Effect of clinically significant thresholds of eosinophil elevation on health care resource use in asthma

Blood eosinophil counts correlate with exacerbations, but there is a lack of consensus on a clinically relevant definition of eosinophil count elevation.

To analyze health care resource use among patients with elevated blood eosinophil counts defined at 150 cells/μL or greater and 300 cells/μL or greater.

Data on patients who received a diagnosis of asthma between 2007 and 2016 were extracted from EMRClaims + database. Patients were defined as having elevated eosinophil counts if any test result during 3 months before follow-up found blood eosinophil count of 150 cells/μL or more or 300 cells/μL or more. Hospitalizations, emergency department visits, outpatient visits, and associated costs were compared. With logistic regression, likelihood of hospitalization was assessed in the presence of eosinophil elevation.

Among 3687 patients who met the study criteria, 1152 received a test within 3 months before the follow-up period, of whom 644 (56%) had elevated eosinophil counts of 150 cells/μL or greater and 322 (29%) had eosinophil counts of 300 cells/μL or greater. Overall, the mean (SD) number of hospitalizations for patients with elevated eosinophil counts vs the comparator was significantly greater (0.29 [0.92] vs 0.17 [0.57], P < .001 at ≥150 cells/μL and 0.30 [0.95] vs 0.18 [0.61] at ≥300 cells/μL, P = .001). The total mean cost was significantly greater for patients with elevated eosinophil counts (at ≥150 cells/μL: $10,262 vs $7149, P < .001 and at ≥300 cells/μL: $9966 vs $7468, P = .003).

Patients with asthma incurred greater health care resource use when their blood eosinophil counts were elevated at 150 cells/μL or greater and 300 cells/μL or greater as measured within 3 months of follow-up.