2.5 Data extraction
Two authors (J Jiang and D Zhang) independently extracted data and cross-checked, disagreements were resolved with the help of W Zhang. The extracted contents included: (a) Basic research information: first author and publication year; (b) Study characteristics: patient age, sample size, intervention measures, intervention site, treatment frequency and treatment time. (c) Outcome measures were as follows: 6MWT, PAQLQ, FEF25-75% pred, FEV1% pred and FVC% pred.