A Cochrane review [Abstract] 1 included 4 studies with a total of 302 subjects. Time range was 29 days to 12 months. There were no differences in either the number of respiratory exacerbations or the number of participants with an exacerbation between cystic fibrosis transmembrane conductance regulator (CFTR) gene transfer replacement therapy or placebo groups at any time point. Most respiratory function tests (FEV1, FEV1%,FVC) showed no difference between treatment and placebo groups, but the smallest study (n=16) reported forced vital capacity (litres) increased more in the placebo group at up to 24 hours. The more recent study (n=140) demonstrated a small improvement in FVC at 2 and 3 months and again at 11 and 12 months with gene replacement therapy compared with placebo.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment) and by imprecise results ( few patients and wide confidence intervals).
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