A study theorized that many extra-intestinal symptoms reported as adverse events in clinical trials on irritable bowel syndrome (IBS) may actually be pre-existing symptoms that are misattributed to side effects from the study intervention. The study, led by Sarah Ballou, and published in Clinical Gastroenterology and Hepatology, suggested that “participants with IBS often experience extra-intestinal symptoms at baseline and that these symptoms generally improve in severity of the course of the a clinical trial, regardless of the treatment arm.”
The authors’ analysis included 173 patients from a six-week clinical trial on IBS. The participants in the trial were randomized to groups of 30, 71, and 72 patients, which received double-blind peppermint oil (DBM), double-blind placebo (DBP), or treatment as usual (TAU), respectively.
Each group presented with approximately five extra-intestinal symptoms per participant at baseline. That number decreased to an average of three by the final study visit, “and this change was statistically significant in all groups (p <0.001),” the investigators added. Notably, when individual extra-intestinal symptoms were assessed, most patients did not report new or worsened symptoms. “In fact, between the baseline assessment and the final assessment, the average symptom severity decreased significantly in all three groups (p <0.001),” wrote Ballou.
In closing, the authors posited that “systematic assessment of extra-intestinal symptoms at the beginning of a clinical trial is necessary to determine more definitively whether these symptoms may be considered an adverse event attributable to a study medication.”