Figure 1From: Lung function decline in relation to diagnostic criteria for airflow obstruction in respiratory symptomatic subjects Selection of study subjects from the initial primary care diagnostic centres' spirometry databases. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; LLN: lower limit of normal. * based on Swanney prediction equations for FEV1/FVC [6] †subgroups D, E, and F in Figure 2b ‡ subgroups A, B, and C in Figure 2b.Back to article page