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Distribution of included subjects with respect to obstructive ventilatory defect definitions and smoking status: (a) operational definition ‘negative’; (b) operational definition ‘positive’.
FEV1, first-second forced expiratory volume; FVC, forced vital capacity; LLN, lower limit of normal; n, number; %: percentage of smokers with OVD; FEV1/FVC LLN values are mean±SD.
