IMPACT OF BASELINE EOSINOPHILS ON FUTURE EXACERBATIONS IN PATIENTS WITH MODERATE-TO-SEVERE ASTHMA

Introduction Elevated eosinophils (EOS) are one marker for Type 2 asthma. We assessed the association between baseline EOS and severe asthma exacerbations. Methods Data from the Clinical Practice Research Datalink identified adult patients with clinical diagnosis codes for asthma and prescription utilization patterns indicative of moderate-to-severe asthma (Step 3–5 per British Thoracic Society 2011 guidelines). Date of first asthma prescription during 01JAN2010–31DEC2012 was the index date. Patients had 12-months pre-index and 36-months post-index data. Patients were stratified by baseline EOS (nearest EOS result ±180 days of index date): Level 1 (L1), 3 ; L2, 150–299 cells/mm 3 ; L3, 300–499 cells/mm 3 ; L4, ≥500 cells/mm 3 . Risk of severe exacerbations during the post-index period was reported using hazard ratios (HRs) and incident rate ratios (IRRs). Results Overall, 36,614 patients were identified, of which 12,155 had baseline EOS measurements. There were no significant differences in HRs for time to first exacerbation in L2 and L3 patients compared with L1; however, patients in L4 had a significantly greater risk of exacerbations. Unadjusted exacerbation rates per patient per year by EOS category were: L1 (0.42), L2 (0.41), L3 (0.44), and L4 (0.50). IRRs for exacerbations were similar in L2 and L3 patients compared with L1; however, L4 patients had significantly higher exacerbation rates (see Table). Conclusions Given that severe exacerbation rates were not associated with baseline EOS levels except for EOS ≥500 cells/mm 3 , baseline EOS may not be a consistent predictor of exacerbations; therefore, other potential predictors of exacerbations should be explored. Table. Severe exacerbation risk over the follow-up period categorized by baseline eosinophil level in patients with moderate-to-severe asthma