Table 3.

Risk of bias among 28 included randomized controlled trials.

First author	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data addressed	Selective outcome reporting
Xu and colleagues75	Unclear risk Quote: ‘All 61 patients were randomly and voluntarily divided into two groups.’ However, the method of random sequence generation was not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture plus moxibustion group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 61 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Sun and colleagues70	Low risk Quote: ‘The 63 patients were assigned by a random number table to two groups.’	Unclear risk Details not stated.	High risk Although the study was a single-blinded randomized control study, the blinded party was not mentioned. Blinding was not possible in the study as participants were either randomized to needle acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Low risk 60 out of 63 patients completed the study. Drop-out rate: 5.0%	Unclear risk Protocol is not available.
Luo and colleagues66	Unclear risk Quote: ‘95 patients were randomly divided into two groups.’ Random sequence generation method was not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to moxibustion group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 95 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Liu64	Unclear risk Quote: ‘Patients were randomized based on admission sequence.’ Random sequence generation method not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 60 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Kong and colleagues56	Low risk Quote: ‘Patients were randomized using a random number table into two groups.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Low risk: 57 out of 60 patients completed the study. Drop-out rate: 5.0%.	Unclear risk Protocol is not available.
Wei and colleagues72	Unclear risk Details not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 60 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Liu and Wang61	Unclear risk Quote: ‘Patients were randomized into treatment and control group.’ Random sequence generation method not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to electroacupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 60 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Sun and Song71	Low risk Quote: ‘60 patients were randomized using a random number table.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to electroacupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 60 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Li and colleagues57	Low risk Quote: ‘Patients recruited were randomized using a random number table.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to electroacupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 70 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Li59	Unclear risk Quote: ‘64 patients were randomized into treatment and control group.’ Random sequence generation method not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Low risk: 60 out of 64 patients completed the study. Drop-out rate: 6.3%.	Unclear risk Protocol is not available.
Li and colleagues58	Low risk Quote: ‘Patients recruited were randomized using a random number table.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 60 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Wu and Gao74	Unclear risk Quote: ‘Patients were randomized based on admission sequence.’ Random sequence generation method not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to electroacupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 60 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Pei and colleagues67	Low risk Quote: ‘65 eligible patients were randomized using a random number table.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Low risk: 60 out of 65 patients completed the study. Drop-out rate: 7.7%.	Unclear risk Protocol is not available.
Gao35	Low risk Quote: ‘A random number table was used to assign included patients into treatment and control group.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to periorbital acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Low risk: 60 out of 64 patients completed the study. Drop-out rate: 6.3%.	Unclear risk Protocol is not available.
Liu36	Unclear risk Quote: ‘60 patients were assigned into treatment and control group with randomized method.’ Random sequence generation method not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to periorbital acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Low risk: 58 out of 60 patients completed the study. Drop-out rate: 3.3%.	Unclear risk Protocol is not available.
Zeng and colleagues77	Low risk Quote: ‘The 65 patients were assigned by a random number table to two groups.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture plus moxibustion group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Low risk 61 out of 65 patients completed the study. Drop-out rate: 6.2%	Unclear risk Protocol is not available.
Shi and colleagues69	Low risk Quote: ‘The 40 patients were assigned by simple randomization to two groups.’	Unclear risk Details not stated.	High risk Although the study was a single-blinded randomized control study, the blinded party was not mentioned. Blinding was not possible in the study as participants were either randomized to needle acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 40 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Liu65	Unclear risk Quote: ‘Patients were randomized into treatment and control group.’ Random sequence generation method not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 62 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Shi and colleagues68	Low risk Quote: ‘Blocked randomization and random number table were used to assign 120 patients into treatment and control group.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to electroacupuncture group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 120 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Yao76	Low risk Quote: ‘Patients were randomized using a random number table.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to catgut embedding plus medication group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 60 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Guo and colleagues55	Unclear risk Quote: ‘The 100 patients were assigned to two groups using a randomized design.’ Random sequence generation method not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture plus moxibustion group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 100 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Chu and colleagues53	Low risk Quote: ‘The 60 patients were assigned by a random number table to two groups.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to moxibustion group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 60 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Ge and Zeng54	Low risk Quote: ‘(Patients were) divided into a warm needling group and a western medicine group by using random digits table method.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture plus moxibustion group or medication group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 120 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Liu and colleagues63	Low risk Quote: ‘The 300 patients were assigned by a random number table to four groups.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture plus Chinese herbal medicine (Geshanxiaoyao formula) group or Bifidobacterium group or Chinese herbal medicine (Geshanxiaoyao formula)-alone group or needle acupuncture alone group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 300 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.
Liu62	Low risk Quote: ‘Randomization was done using a random number table.’	Low risk Quote: ‘Random numbers were marked and put into opaque envelopes.’	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to catgut embedding group or Chinese herbal medicine (Tongxieyaofang) group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Low risk: 59 out of 60 patients completed the study. Drop-out rate: 1.7%.	Unclear risk Protocol is not available.
Wen73	Low risk Quote: ‘Two groups of patients were divided based on randomization from random number table.’	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture group or Chinese herbal medicine (Tongxieyaofang) group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Low risk: All patients completed the study. Drop-out rate: 0%.	Unclear risk Protocol is not available.
Liao60	Unclear risk Quote: ‘132 eligible patients were randomized into treatment and control group.’ Random sequence generation method not stated.	Unclear risk Details not stated.	High risk Although the study did not mention blinding of participants and researchers, blinding was not possible as participants were either randomized to needle acupuncture group or Chinese herbal medicine (Tongxieyaofang) group.	High risk Blinding of assessors was not mentioned and its impact may be high as global IBS symptoms improvement was a subjective outcome measure.	Unclear risk: 132 patients were randomized while the author did not mention the follow-up rate.	Unclear risk Protocol is not available.

IBS, irritable bowel syndrome.