“…This should not obscure the fact that up to 20% of the patients do not experience an improvement either subjectively or in the pulmonary function tests [4, 39, 41, 42, 45±48, 51, 52, 54, 57, 61, 62] and that mortality is not negligible [4,39,40,43,47,49,50,52,54,58,99], reaching 10% in some series [49]. The determinants of outcome have not yet received much attention.…”