Results The overall response rate was 61%. The adjusted difference in mean IBS SSS at 24 months was −18.28 (95% CI −40.95 to 4.40) in favour of the acupuncture arm. Differences at earlier time points estimated from the multivariate model were: −27.27 (−47.69 to −6.86) at 3 months; −23.69 (−45.17 to −2.21) at 6 months; −24.09 (−45.59 to −2.59) at 9 months; and −23.06 (−44.52 to −1.59) at 12 months.