Fig. 1From: Proportions and risk factors of chronic obstructive pulmonary disease and preserved ratio impaired spirometry, and association with small airway disease, in the positive screening older population from China: a cross-sectional studyStudy flow chart. Abbreviations: COPD:Chronic obstructive pulmonary disease; PRISmPreserved ratio impaired spirometry; COPD-SQ:COPD screening questionnaire; CAT:COPD assessment test; FEV1/FVC:Forced expiratory volume in 1 s/forced vital capacityBack to article page