Omalizumab for the treatment of severe persistent allergic asthma: a systematic review and economic evaluation

Allergic asthma is a long-term disorder of the airways resulting from overexpression of immunoglobulin E (IgE) in response to environmental allergens. Patients with poorly controlled asthma are at high risk of exacerbations requiring additional treatment, including hospitalisations. Severe exacerbations are potentially life threatening. Guidelines identify five treatment steps for both adults and children. Omalizumab (Xolair(®)) is a recombinant DNA-derived humanised monoclonal antibody indicated as an add-on therapy in patients aged ≥ 6 years with severe persistent allergic asthma uncontrolled at treatment step 4 or 5. To determine the clinical effectiveness, safety and cost-effectiveness of omalizumab, as an add-on therapy to standard care, within its licensed indication, compared with standard therapy alone for the treatment of severe persistent allergic asthma in adults and adolescents aged ≥ 12 years and children aged 6-11 years. Eleven electronic databases (including MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials) and additional sources including regulatory agency reports were searched from inception to October 2011. Additional data sources include: the manufacturer's submission (MS); two previous National Institute for Health and Care Excellence (NICE) single technology appraisal (STA) submissions; and existing reviews on the safety of omalizumab and oral corticosteroids (OCSs). Systematic reviews of the clinical effectiveness and cost-effectiveness evidence for omalizumab were performed. The primary outcome was number of clinically significant (CS) exacerbations. Other outcomes included asthma symptoms, unscheduled health-care use, asthma-related mortality, OCS use and health-related quality of life (HRQoL). Because of methodological and clinical heterogeneity between trials, a narrative synthesis was applied. Pragmatic reviews with best evidence syntheses were used to assess adverse events of omalizumab and OCSs. The cost-effectiveness of omalizumab was assessed from the perspective of the UK NHS in the two separate populations: adults and adolescents, and children, using a cohort Markov model. Costs and outcomes were discounted at 3.5% per annum. Results are presented for additional subgroup populations: (1) hospitalised for asthma in the previous year, (2) adults and adolescents on maintenance OCSs and (3) three or more exacerbations in the previous year. Eleven randomised controlled trials (RCTs) and 13 observational stu