Table 5.

Results of evidence quality.

Citation	Outcomes	Limitations	Inconsistency	Indirectness	Imprecision	Publication bias	Quality
Cao et al. [21]	FEV1	-1①	-1②	0	0	-1④	Very low
	FVC	-1①	-1②	0	0	-1④	Very low
	FEV1/FVC	-1①	-1②	0	0	-1④	Very low
	6-MWD	-1①	-1②	0	0	-1④	Very low
	SGRQ	-1①	-1②	0	0	-1④	Very low
	CAT	-1①	-1②	0	0	-1④	Very low
Liu et al. [22]	6-MWD	0	-1②	0	0	0	Moderate
	FEV1	0	-1②	0	0	0	Moderate
	FEV1%	0	-1②	0	0	0	Moderate
	FVC	0	0	0	0	0	High
	FEV1/FVC	0	-1②	0	0	0	Moderate
	Quality of life	0	-1②	0	0	0	Moderate
Chen et al. [23]	FEV1	0	0	0	0	-1④	Moderate
	FEV1%	0	0	0	0	-1④	Moderate
	FVC	0	0	0	0	-1④	Moderate
	FEV1/FVC	0	-1②	0	0	-1④	Low
	CAT	0	-1②	0	0	-1④	Low
Han et al. [24]	6-MWD	0	0	0	-1③	-1④	Low
	FEV1	0	-1②	0	0	-1④	Low
	FEV1%	0	0	0	0	-1④	Moderate
	FVC	0	0	0	-1③	-1④	Low
	FEV1/FVC	0	-1②	0	-1③	-1④	Very low
Li et al. [25]	FEV1/pred%	0	-1②	0	0	-1④	Low
	FEV1	0	-1②	0	-1③	0	Low
	FEV1%	0	-1②	0	0	0	Moderate
	FVC	0	0	0	-1③	0	Moderate
	6-MWD	0	-1②	0	0	0	Very low
Xie et al. [26]	6-MWD	-1①	-1②	0	0	-1④	Very low
	FEV1	-1①	-1②	0	0	-1④	Very low
	FEV1%	-1①	-1②	0	0	0	Low
	FVC	-1①	-1②	0	0	-1④	Very low
	FEV1/FVC	-1①	-1②	0	0	-1④	Very low
	CAT	0	-1②	0	-1③	-1④	Very low
	SGRQ	-1①	-1②	0	0	-1④	Very low
	WHOQOL-BREF	0	-1②	0	0	-1④	Low
Xiao et al. [27]	MRC	0	-1②	0	-1③	-1④	Very low
	6-MWD	0	0	0	-1③	-1④	Low
	FEV1	0	-1②	0	0	-1④	Low
	FEV1/pred%	-1①	-1②	0	0	-1④	Very low
	FEV1/FVC	0	-1②	0	0	-1④	Low
	CAT	0	-1②	0	0	-1④	Low
	SGRQ	0	-1②	0	-1③	-1④	Very low
Gao et al. [28]	MRC	0	0	0	0	-1④	Moderate
	6-MWD	0	0	0	0	0	High
	FEV1	0	0	0	0	0	High
	FEV1%	0	-1②	0	0	0	Moderate
	FEV1/FVC	0	-1②	0	0	0	Moderate
	Quality of life	0	-1②	0	0	-1④	Low
Liu et al. [29]	6-MWD	-1①	0	0	-1③	-1④	Very low
	FEV1	-1①	0	0	-1③	-1④	Very low
	FEV1%	-1①	0	0	-1③	-1④	Very low
Zhang et al. [30]	MRC	-1①	0	0	-1③	-1④	Very low
	6-MWD	0	-1②	0	0	-1④	Low
	FEV1	-1①	-1②	0	-1③	-1④	Very low
	FEV1%	-1①	-1②	0	0	-1④	Very low
	CAT	-1①	0	0	-1③	-1④	Very low
Tong et al. [31]	6-MWD	0	-1②	0	0	-1④	Low
	FEV1	0	-1②	0	0	-1④	Low
	FEV1/FVC	0	0	0	0	-1④	Moderate
	FEV1%	0	-1②	0	0	-1④	Low
	CAT	0	-1②	0	-1③	-1④	Very low
Li et al. [32]	FEV1% (3 months)	0	0	0	0	-1④	Moderate
	FEV1% (6 months)	0	-1②	0	0	-1④	Low
	FEV1/FVC (3 months)	0	-1②	0	0	-1④	Low
	FEV1/FVC (6 months)	0	-1②	0	0	-1④	Low
	CAT	0	0	0	-1③	-1④	Low
	6-MWD (3 months)	0	0	0	0	-1④	Moderate
	6-MWD (6 months)	0	-1②	0	0	-1④	Low
Yuan et al. [33]	FEV1	-1①	-1②	0	-1③	-1④	Very low
	FEV1%	-1①	-1②	0	-1③	-1④	Very low
	FEV1/FVC	-1①	-1②	0	0	-1④	Very low
	FEV1/pred%	-1①	-1②	0	-1③	-1④	Very low
	6-MWD	-1①	-1②	0	-1③	-1④	Very low

Note: ① the included studies have a large bias in methodology such as randomization, allocation concealment, and blinding. ② The confidence interval overlaps less or the I² value of the combined results was larger. ③ The sample size from the included studies does not meet the optimal sample size or the 95% confidence interval crosses the invalid line. ④ The funnel chart is asymmetry; FEV1: the forced expiratory volume in one second; FVC: forced vital capacity; 6-MWD: 6 min walking distance; FEV1/FVC: the amount of air exhaled in the first second divided by all of the air exhaled during a maximal exhalation; SGRQ: St George's respiratory questionnaire; CAT: COPD assessment test; FEV1%: percentage of the forced expiratory volume in one second; QOL: quality of life; WHOQOL-BREF: the World Health Organization on quality of life brief scale; MRC: medical research council dyspnea scale; FEV1%pred: the percentage of predicted values of FEV1.