METHODS: Poisson regression analysis examined exacerbation rate reductions for omalizumab versus placebo at Week 24 stratified by median CASI score at baseline (≤7 (n=360) vs. >7 (n=216)). A higher CASI score indicates more severe asthma. Clinically significant exacerbations were defined as those requiring either systemic corticosteroid therapy or a doubling of baseline inhaled corticosteroid dose for ≥3 days.
RESULTS: Baseline age, sex, total IgE and eosinophil levels were similar between treatment groups and across CASI strata. The CASI>7 group had higher proportions of black children, males, lower mean percent predicted pre-bronchodilator FEV1, and greater maximum reversibility than the CASI≤7 group. Exacerbation rates were reduced by the following for omalizumab versus placebo: CASI≤7, 20% (-16%, 44%; p=0.24); CASI>7, 45% (18%, 63%; p=0.004).
CONCLUSIONS: CASI is a useful clinical tool to identify children who are likely to achieve favorable response to omalizumab. In children with greater asthma severity, as measured by a higher CASI score, a significantly greater response to omalizumab was observed for exacerbation reduction versus placebo; children with lower CASI scores had nonsignificant differences in reductions in exacerbation rates.