Based on our results, an admission CRP of greater than 75 mg/L, which was present in about one-quarter of PEx events, demonstrated high specificity (90%) for the prediction of treatment non-response and might be used in future interventional CF PEx trials to target patients at high risk of treatment failure and who might benefit from short courses of systemic corticosteroids [34]. This evidence concerns the gene CRP and cystic fibrosis.