TY - JOUR T1 - Stitching and switching: the impact of discontinuous lung function reference equations JF - European Respiratory Journal JO - Eur Respir J SP - 1256 LP - 1257 DO - 10.1183/09031936.00173011 VL - 39 IS - 5 AU - Jane Kirkby AU - Paul Aurora AU - Helen Spencer AU - Stephanie Rees AU - Samantha Sonnappa AU - Janet Stocks Y1 - 2012/05/01 UR - http://erj.ersjournals.com/content/39/5/1256.abstract N2 - To the Editors:In order to distinguish the effects of lung disease from those of normal growth and development, lung function is expressed in comparison with reference data, with forced expiratory volume in 1 s (FEV1) commonly being presented as % predicted. FEV1 % pred has been identified as being of prognostic value in cystic fibrosis (CF), such that an FEV1 of <30% pred or rapid decline to that level should prompt referral to a transplant centre [1]. Subsequent monitoring of FEV1 % pred after lung transplantation is also important for monitoring graft function and is required to detect any signs of rejection or onset of bronchiolitis obliterans syndrome (BOS), a disease defined as a fall in FEV1 of >20% from baseline determined by the average of two measurements made ≥3 weeks apart. Continuing to monitor FEV1 % pred after the development of BOS has also been shown to provide important insight into the patient’s prognosis and therapeutic options [2].Given that FEV1 % pred plays such a key role in the clinical management of a child with CF or any child who has undergone lung transplantation, it is imperative to ensure that it is measured and interpreted accurately. Although guidelines for standardised measurement of spirometry have been developed for both adults [3] and children [4], the decision on which spirometry reference equation to use, amongst the plethora available [5], varies widely. This situation is further complicated by … ER -