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Fig. 1 | BMC Pulmonary Medicine

Fig. 1

From: REALizing and improving management of stable COPD in China: a multi-center, prospective, observational study to realize the current situation of COPD patients in China (REAL) – rationale, study design, and protocol

Fig. 1

Multi-stage, stratified, cluster sampling method. * All secondary and tertiary hospitals administered by NHFPC. † Excluding traditional Chinese medicine hospitals; the actual hospital number and the ratio of tertiary to secondary hospitals in each region may be adjusted based on the hospital distribution in the region; subject numbers may be adjusted according to COPD outpatient numbers at the site

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BMC Pulmonary Medicine

ISSN: 1471-2466

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