Sites must be tier 3 hospitals in China. Investigators will mainly be determined according to the following criteria:
* Respiratory physicians working in the respiratory department of tier 3 hospitals
* To include the expected number of patients in a maximum of 12 months, physicians should manage a reasonable number of asthma, COPD or ACOS over age 40 with persistent airflow limitation (post-BD FEV1/FVC\<0.7).
* Physicians should have patients' spirometric data available in the patient's medical files (post-BD FEV1%pred and post-BD FEV1/FVC).
This NIS will collect the data (e.g. medical record, patient or physician-reported data) from about 2000 consecutive outpatients with persistent airflow limitation(post-BD FEV1/FVC\<0.7) in about 20 sites in China for one year. Each site will recruit about 50-150 patients successively.
The data will be collected under routine clinical practice. The treatments or examinations will be determined by their treating physicians. The data are expected to reflect the actual situation about ACOS.
The study population will be about 2000 outpatients, men or women, over age 40, with a clinical diagnosis of asthma, COPD or ACOS with persistent airflow limitation（post-BD FEV1/FVC\<0.7）in China from Q4,2015 to Q3,2016.
