Open-label placebo (OLP) is significantly better than no-pill control (NPC) and is similar to double-blind placebo (DBP) for improving symptoms among patients with irritable bowel syndrome (IBS), according to a study in Pain.
In the 6-week, randomized clinical trial, researchers sought to determine whether OLP treatment was superior to NPC in patients with IBS and to compare the efficacy of OLP with DBP. The analysis included 262 participants randomized into 1 of 3 groups: those who received OLP (n = 89), those who received DBP (n = 87), and those who received NPC (n = 86). Participants’ mean age was 42.0 years (Standard Deviation [SD], 18.1), 72.9% were women, and 83.6% were white.
The investigators found that mean improvement on the IBS Severity Scoring System (IBS-SSS) from baseline to the 6-week end point was significantly greater among participants in the OLP group compared with those in the NPC group (90.6 vs 52.3, respectively; P = .031). No significant differences were observed between the OLP and DBP groups regarding IBS-SSS improvement (P = .485). The effect sizes were moderate for the OLP group compared with those in the NPC group (d = .43) and small for OLP participants versus DBP participants (d =.10). In addition, DBP was superior to NPC (100.3 vs 52.3; P = .004).
About 70% of OLP and DBP participants reported a 50-point reduction in the IBS-SSS, compared with about 54% of NPC participants. Also, about 30% of OLP and DBP participants reported a 150-point reduction, compared with about 12% of the NPC group.
OLP and DPB had similar effects that did not differ significantly, suggesting that blinding may not be necessary for placebos to be effective. Thus, OLP could play a role in the management of refractory IBS patients, according to the study authors.
“We found that OLP was significantly better than NPC at improving IBS symptoms as measured by our primary outcome (IBS-SSS), as well as by 1 of our secondary outcomes, global improvement (IBS Global Improvement Scale [IBS-GIS]),” the researchers stated. “We also found that improvement in IBS symptoms (IBS-SSS) and global improvement (IBS-GIS) in participants receiving OLP was similar to those receiving DBP.”
One study limitation is that participants may not be representative of the general population of patients with IBS, as they were willing to try OLP and/or herbal medicine, such as peppermint oil, as a treatment. Also, because no objective markers have been associated definitively with IBS, the results are based on the standard measures of self-reported symptoms.
“It appears that in some conditions, concealment or deception is not necessary for patients to benefit from placebo treatment,” the study authors concluded. “Moreover, our data suggest that OLP has comparable efficacy to DBP in IBS. Despite these conclusions, more research is required in order to harness OLP as an ethical and effective treatment for IBS, and perhaps, other chronic functional disorders.”
Lembo A, Kelley JM, Nee J, et al. Open-label placebo vs double-blind placebo for irritable bowel syndrome: a randomized clinical trial. Pain. Published online February 12, 2021. doi: 10.1097/j.pain.0000000000002234