Background: Irritable bowel syndrome (IBS), a disorder of altered bowel habits associated with abdominal pain or discomfort. The pain, discomfort, and impairment from IBS often lead to healthcare medical consultation (Talley 1997) and workplace absenteeism, and associated economic costs (Leong 2003). A recent randomized controlled trial shows variable results but no clear evidence in support of acupuncture as an effective treatment for IBS (Fireman 2001).

Objectives: The objective of this systematic review is to determine whether acupuncture is more effective than no treatment, more effective than 'sham' (placebo) acupuncture, and as effective as other interventions used to treat irritable bowel syndrome. Adverse events associated with acupuncture were also assessed.

Search strategy: The following electronic bibliographic databases were searched irrespective of language, date of publication, and publication status: MEDLINE, the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library, EMBASE, the Chinese Biomedical Database, the Cumulative Index to Nursing and Allied Health (CINAHL), and the Allied and Complementary Medicine Database (AMED). References in relevant reviews and RCTs were screened by hand. The last date for searching for studies was 7 February 2006.

Selection criteria: Published reports of randomized controlled trials (RCTs) and quasi-randomised trials of acupuncture therapy for IBS.

Data collection and analysis: All eligible records identified were dually evaluated for eligibility and dually abstracted. Methodological quality was assessed using the Jadad scale and the Linde Internal Validity Scale. Data from individual trials were combined for meta-analysis when the interventions were sufficiently similar. Heterogeneity was assessed using the I squared statistic.

Main results: Six trials were included. The proportion of responders, as assessed by either the global symptom score or the patient-determined treatment success rate, did not show a significant difference between the acupuncture and the sham acupuncture group with a pooled relative risk of 1.28 (95% CI 0.83 to 1.98; n=109). Acupuncture treatment was also not significantly more effective than sham acupuncture for overall general well-being, individual symptoms (e.g., abdominal pain, defecation difficulties, diarrhea, and bloating), the number of improved patients assessed by blinded clinician, or the EuroQol score. For two of the studies without a sham control, acupuncture was more effective than control treatment for the improvement of symptoms: acupuncture versus herbal medication with a RR of 1.14(95% CI 1.00 to 1.31; n=132); acupuncture plus psychotherapy versus psychotherapy alone with a RR of 1.20 (95% CI 1.03 to 1.39; n=100). When the effect of ear acupuncture treatment was compared to an unclearly specified combination of one or more of the drugs diazepam, perphenazine or domperidone, the difference was not statistically significant with a RR of 1.49(95% CI 0.94 to 2.34; n=48).

Authors' conclusions: Most of the trials included in this review were of poor quality and were heterogeneous in terms of interventions, controls, and outcomes measured. With the exception of one outcome in common between two trials, data were not combined. Therefore, it is still inconclusive whether acupuncture is more effective than sham acupuncture or other interventions for treating IBS.