Omalizumab for the Treatment of Severe Persistent Allergic Asthma in Children Aged 6–11 Years

Jane Burch, Susan Griffin, Claire McKenna, Simon Walker, James Paton, Kath Wright, Nerys Woolacott

Following a licence extension to include those aged 6-11 years, the National Institute for Health and Clinical Excellence (NICE) invited the manufacturer of omalizumab (Novartis Pharmaceuticals UK) to submit evidence for the clinical and cost effectiveness of this drug for patients with severe persistent allergic asthma in this age bracket. NICE had previously considered the use of omalizumab in patients aged 12 years and over. The Centre for Reviews and Dissemination (CRD) and the Centre for Health Economics (CHE) at the University of York were commissioned as the Evidence Review Group (ERG) to critically appraise the evidence presented by the manufacturer. This article summarizes that review of the evidence, the deliberations of the NICE Appraisal Committee and the resulting NICE guidance. The ERG critically reviewed the evidence presented in the manufacturer's submission and identified areas requiring clarification, for which the manufacturer provided additional evidence. The relevant patient population was patients aged 6-11 years of age with severe persistent allergic immunoglobulin E-mediated asthma whose condition remained uncontrolled despite best standard care with high-dose inhaled corticosteroids and a long-acting inhaled β₂-agonist. The main clinical effectiveness data were derived from a pre-planned subgroup analysis of a single randomized controlled trial comparing omalizumab plus standard therapy against standard therapy alone. At a 52-week follow-up, the only outcome to show a statistically significant benefit of omalizumab compared with placebo was the number of exacerbations defined as 'clinically significant' [CS] (relative risk [RR] 0.504; 95% CI 0.350, 0.725; p < 0.001). At the ERG's request, the manufacturer provided analyses stratified by baseline exacerbation rate, which indicated the effect of omalizumab on CS exacerbations was statistically significant only for those children with ≥3 exacerbations as baseline. The ERG identified a number of issues relating to the clinical effectiveness results: it was unclear whether the pre-planned subgroup analysis had sufficient power; the definition of CS exacerbation was less severe than that used in UK clinical practice; and the method for imputing exacerbations for those who withdrew from treatment may have underestimated the exacerbation rate. The incremental cost-effectiveness ratio based on the manufacturer's results was considerably above the threshold range stated in the NICE Guide to the Methods of Technology Appraisal. The ERG identified numerous issues relating to the cost-effectiveness results, which included the following: the 10-year time horizon for treatment may exceed that in clinical practice; the assumption of constant exacerbation rates over a lifetime given that adolescence is expected to impact on the severity of asthma; and whether it is appropriate to use health-related quality-of-life data collected in adults for children. The ERG concluded that omalizumab appears to reduce CS exacerbations but there was no evidence of improvement in daily symptoms, CS severe (CSS) exacerbations or hospitalization rates. The main driver of cost effectiveness was the reduction in asthma-related mortality associated with a reduction in CSS exacerbations. As the number of CSS exacerbations avoided was low, as is asthma-related mortality in children, the potential small gain in QALYs associated with omalizumab was not sufficient to compensate for the high treatment cost even under the most favourable scenario analyses. The Appraisal Committee recommended that omalizumab should not be routinely provided for the treatment of severe persistent allergic asthma in children aged 6-11 years.