Table 1.

Characteristics of 12 included studies

Ref.	Region	Patients		Study design
		Gender	Mean age (yr)
Fang et al[9]	Zhejiang	NA	> 18	CCT study
Cheng et al[16]	Guangzhou	21 M, 3 F	29.3 ± 10.3	Self-control study
Dang et al[17]	Shandong	38 M, 20 F	41	Self-control study
He et al[18]	Beijing	NA	> 18	CCT study
Liu et al[19]	Shandong	17 M, 8 F	39.6 ± 11.2	Self-control study
Liu et al[20]	Hunan	20 M, 10 F	31.4 ± 13.8	Self-control study
Sun et al[21]	Shanghai	9 M, 4 F	34.4 ± 10.4	Self-control study
Sun et al[22]	Shandong	22 M, 7 F	> 18	Self-control study
Tang et al[23]	Beijing	8 M, 1 F	38.2 ± 11.2	RCT study
Tang et al[24]	Guangzhou	16 M, 5 F	31 ± 8.9	CCT study
Wu et al[25]	Shanghai	23 M, 12 F	40.5 ± 10.4	Self-control study
Xia et al[26]	Shandong	28 M, 14 F	35.4 ± 17.1	Self-control study

M: Male; F: Female; NA: Not available; RCT: Randomized controlled trial; CCT: Clinical controlled trial.