TY - JOUR T1 - Age- and height-based prediction bias in spirometry reference equations JF - European Respiratory Journal JO - Eur Respir J DO - 10.1183/09031936.00161011 SP - erj01610-2011 AU - P.H. Quanjer AU - G.L. Hall AU - S. Stanojevic AU - T.J. Cole AU - J. Stocks AU - on behalf of the Global Lungs Initiative Y1 - 2012/01/01 UR - http://erj.ersjournals.com/content/early/2011/12/16/09031936.00161011.abstract N2 - Prediction bias in spirometry reference equations can arise from combining equations for different age groups, rounding age or height to integers or using self-reported height.To assess the bias arising from these sources.The fit of 13 prediction equations was tested against the Global Lungs Initiative (GLI) dataset using spirometric data from 55,136 healthy Caucasians (54% female). The effects on predicted values of using whole-year age versus decimal age, and of a 1% bias in height, were quantified.In children, the prediction bias relative to GLI ranged from −22% to +17%. Switching equations at 18 years of age led to biases of between −846 (−14%) to +1309 (+38%) mL. Using age in whole years rather than decimal age introduced biases from −8% to +7%, whereas a 1% over-estimation of height introduced bias that ranged from +1% to +40%. Bias was greatest in children and adolescents, and in short elderly subjects.Using a single spirometry equation applicable across all ages and populations reduces prediction bias. Measuring and recording age and height accurately are also essential if bias is to be minimised. ER -