PT - JOURNAL ARTICLE AU - Stuart Elborn AU - Barry Plant AU - Michael Konstan AU - Richard Aherns AU - Sally Rodriguez AU - Anne Munck AU - Charles Johnson TI - Lung function, weight, and sweat chloride responses in patients with cystic fibrosis and the <em>G551D-CFTR</em> mutation treated with ivacaftor: A secondary analysis DP - 2013 Sep 01 TA - European Respiratory Journal PG - 5059 VI - 42 IP - Suppl 57 4099 - http://erj.ersjournals.com/content/42/Suppl_57/5059.short 4100 - http://erj.ersjournals.com/content/42/Suppl_57/5059.full SO - Eur Respir J2013 Sep 01; 42 AB - Clinical studies show improved FEV1 in ivacaftor-treated CF patients with the G551D-CFTR mutation when compared with placebo. To better understand the clinical benefit for those who fall below the median response, we examined pharmacodynamic and efficacy data from Phase 3 ivacaftor Studies 102/103.This secondary analysis of patients who received 48 weeks of ivacaftor (n=109) or placebo (n=100), examined the number needed to treat (NNT), frequency and cumulative distribution functions and subset analyses to evaluate response (sweat chloride, FEV1, weight). Changes in these outcomes according to FEV1 response were also compared.The NNT for a reduction in sweat chloride of 20 mMol/L was 1.03. To achieve an improvement in FEV1 of ≥5%, NNT was 1.73. For both treatment populations, the data were normally distributed with a shift toward benefit for the ivacaftor group. Numerical differences were seen in sweat chloride and weight for ivacaftor-treated patients, regardless of whether or not a ≥5% FEV1 improvement was achieved (Table).Ivacaftor was observed to produce an effect on sweat chloride, FEV1, and weight. These analyses indicate that in % predicted FEV1 responders (&gt;5% improvement) and minimal responders (&lt;5% improvement) weight gain and change in sweat chloride are similar.