TY - JOUR T1 - Question everything JF - European Respiratory Journal JO - Eur Respir J SP - 947 LP - 948 DO - 10.1183/09031936.00023814 VL - 43 IS - 4 AU - Riccardo Pellegrino AU - Vito Brusasco AU - Martin R. Miller Y1 - 2014/04/01 UR - http://erj.ersjournals.com/content/43/4/947.abstract N2 - Advances through scientific endeavour have delivered many benefits to the human race and overall these benefits have outweighed any associated problems. Not uncommonly apparent improvements in our knowledge are eventually shown to be incorrect or misguided in the light of subsequent knowledge. This might arise because a different perspective was taken on a problem so that a new understanding was achieved or it might arise because technological advances revealed imperfections in previous studies.In the early 1960s a view became common practice that expressing results as a percentage of the predicted value was the best way to look at lung function and that 80% of predicted was “as a rule of thumb” the lower limit of normality [1]. This view was immediately challenged [2] but the practice persisted, despite the fact it retains age, sex and height biases [3], and is not true for all lung function indices. In 1972 the forced expiratory flow between 25% and 75% (FEF25–75%) of forced vital capacity (FVC) was proposed as a more sensitive test of small airways disease [4], with evidence presented from 53 heavy smokers who did not have asthma and had normal forced expiratory volume in 1 s (FEV1), FVC and their ratio, but with FEF25–75% that was deemed abnormal (below … ER -