Ivacaftor for the treatment of patients with cystic fibrosis and the G551D mutation: a systematic review and cost-effectiveness analysis

Ivacaftor (Kalydeco(?), Vertex Pharmaceuticals) is the first of a new class of drugs that target the underlying protein defect in cystic fibrosis (CF). It is aimed at patients with the G551D (glycine to aspartate change in nucleotide 1784 in exon 11) mutation; 5.7% of patients with CF in the UK have this mutation.To review the clinical effectiveness and cost-effectiveness of ivacaftor for the treatment of CF in patients aged ? 6 years who have the G551D mutation.Ten databases, including MEDLINE and EMBASE, were searched from inception to July 2012. Studies that evaluated ivacaftor for the treatment of adults and children (? 6 years) with at least one G551D mutation were eligible. There were insufficient data to conduct a formal meta-analysis. The manufacturer of ivacaftor, Vertex Pharmaceuticals, submitted a deterministic patient-level simulation model for the assessment of the lifetime cost-effectiveness of ivacaftor. We modified the model where values were not UK-specific or not recent, or where better estimates could be found. The only change to the model structure was the addition of lung transplantations. We changed utility values, annual decline in percentage predicted forced expiratory volume in 1 second (FEV1), and the baseline exacerbation rate, and used data from the CF Registry to estimate the relation between costs, age and percentage predicted FEV1. Estimates of treatment effect of ivacaftor came from the clinical effectiveness review. We modelled three scenarios for the longer-term effects of ivacaftor. We also modelled an 'optimistic' scenario for patients aged