Table 2.

Detailed risk of bias of each trial

	Random sequence generation	Allocation concealment	Blinding of participants	Blinding of outcome assessment	Incomplete outcome data	Selective outcome reporting	Other sources of bias
AcuTENS
Lau, 2008 [9]	Low	Low	Low	Low	Low	Unclear	Low
Liu X, 2015 [10]	Low	Low	Low	Low	Low	Unclear	Low
Ngai, 2010 [11]	Low	Unclear	Low	Low	Low	Unclear	Low
Jones, 2011 [12]	Low	Unclear	Low	Low	Unclear	High	Unclear
Öncü, 2017 [13]	Low	Unclear	Low	Unclear	Unclear	Unclear	Unclear
Shou, 2014 [14]	Low	Unclear	Unclear	Unclear	Low	Unclear	Unclear
Wen Q 2011 [15]	Low	Unclear	Low	Unclear	Low	Unclear	Unclear
Moxibustion
Bai 2018 [26]	Unclear	Unclear	High	Unclear	Unclear	Unclear	Unclear
Cheng AP, 2011 [23]	Unclear	Unclear	Unclear	Unclear	Unclear	Low	Unclear
Cui XX, 2015 [22]	Low	Unclear	Unclear	Unclear	Unclear	Low	Unclear
Guang, 2017 [25]	Low	Unclear	High	Unclear	Unclear	Unclear	Unclear
He F, 2013 [21]	Unclear	Unclear	High	High	Unclear	Low	Low
Liang, 2018 [27]	Low	Unclear	High	Unclear	Unclear	Unclear	Unclear
Liu SR, 2015 [20]	Low	Unclear	Unclear	Unclear	Unclear	Low	Unclear
Tang J 2012 [19]	Unclear	Unclear	Unclear	Unclear	Unclear	Low	Unclear
Wang WH, 2016 [18]	Unclear	Unclear	Unclear	Unclear	Low	Unclear	Unclear
Wen X, 2013 [8]	Low	Unclear	Unclear	Unclear	Unclear	Low	Unclear
Yang XQ, 2016 [17]	Low	Unclear	Unclear	Unclear	Unclear	Low	Unclear
Zhang QY, 2016 [16]	Low	Unclear	Unclear	Unclear	Unclear	Low	Unclear
Zhe, 2017 [24]	Low	Unclear	High	Unclear	Unclear	Unclear	Unclear
Acupressure
Guo 2017 [32]	Low	Unclear	High	Unclear	Unclear	Unclear	Unclear
Huang 2018 [33]	Low	Unclear	High	Unclear	Unclear	Unclear	Unclear
Maa, 1997 [30]	Low	Unclear	Low	Unclear	Low	Unclear	Low
Tsay, 2005 [28]	Unclear	Unclear	Low	Low	Low	Unclear	Unclear
Wu, 2004 [31], 2007 [29]	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear	Unclear
Wu, 2017 [34]	Low	Unclear	High	Unclear	Unclear	Unclear	Unclear
Xu 2018 [35]	Unclear	Unclear	High	Unclear	Unclear	Unclear	Unclear
Ear acupuncture
Cao L, 2012 [36]	Low	Low	Low	Low	Low	Unclear	Unclear
Hu ZH, 1997 [41]	Unclear	Unclear	Unclear	Unclear	Low	Unclear	Unclear
Jin RF, 2009 [37]	Unclear	Unclear	Unclear	Unclear	Low	Low	Unclear
Li, 2017 [40]	Unclear	Unclear	High	Unclear	Low	Unclear	Unclear
Pang CL, 2014 [39]	Unclear	Unclear	Unclear	Unclear	Low	Unclear	Unclear
Pang CL, 2016 [38]	Unclear	Unclear	High	Unclear	Low	Low	Unclear
Acupressure plus ear acupuncture
Rao, 2017 [42]	Low	Unclear	High	Unclear	Unclear	Unclear	Unclear
Cupping
Xiao W, 2009 [43]	Unclear	Unclear	High	Unclear	Low	Unclear	Unclear