Examining the Nocebo Effect in Trials of Neuromodulators for Use in Disorders of Gut-Brain Interaction.

INTRODUCTION: Nocebo effects are believed to influence the rate of reported adverse events (AE) and subject withdrawal in both the treatment and placebo groups of randomized clinical trials (RCT). Neuromodulators are commonly prescribed to treat disorders of gut-brain interaction (DGBI), but adherence to these medications is often limited by side effects such as headache, dry mouth, fatigue, and altered bowel habits. We performed a systematic review and meta-analysis to assess the proportion and risk difference of patients who experienced side effects leading to withdrawal in the placebo arm vs the treatment arm of RCT of neuromodulators for DGBI. We also sought to estimate the risk of developing any AE in the placebo arm of these studies and the rate of specific individual AEs. METHODS: We searched MEDLINE, Embase, Web of Science Core Collection, and the Cochrane Central Register of Controlled Trials Searches to identify RCT that included terms for DGBI and for commonly prescribed neuromodulators. We calculated pooled proportions of patients experiencing an AE leading to withdrawal in the active treatment group vs the placebo group with 95% confidence intervals (CI), the pooled proportions of patients experiencing any AE, the pooled proportions of patients experiencing specific AE such as dizziness and headache, the pooled proportions of patients experiencing severe AE, and corresponding pooled risk differences with 95% CI. RESULTS: There were 30 RCT included representing 2,284 patients with DGBI. Twenty-seven RCT reported data on AE leading to withdrawal. The pooled proportion of total patients with AE leading to withdrawal in the placebo group was 4% (95% CI 0.02-0.04). The pooled proportion of patients with AE leading to withdrawal who received neuromodulators was 9% (95% CI 0.06-0.13). In the 12 studies reporting data on patients experiencing at least 1 AE, the pooled proportion of patients experiencing any AE in the placebo group was 18% (95% CI 0.08-0.30), compared with 43% (95% CI 0.24-0.63) in the neuromodulator group. Thus, approximately 44% of the rate of withdrawal (0.04/0.09) and 42% of the rate reporting any side effects (0.18/0.43) in the neuromodulator group may be attributed to nocebo effects in the right context. Subgroup analysis by sex, medication class, risk of bias, and specific DGBI revealed differing withdrawal rates. There was no statistically significant difference in patients experiencing individual AE of dizziness, headache, or diarrhea. Rates of dry mouth, fatigue, and constipation were higher in treatment groups compared with those in placebo groups. DISCUSSION: Patients with DGBI in RCT randomized to placebo groups frequently experience AE and AE that lead to withdrawal consistent with a strong nocebo effect. Nonspecific AE such as dizziness, headaches, and diarrhea occurred similarly in patients receiving placebo compared with those receiving neuromodulators.

What Is Unspecified Functional Bowel Disorder? A Commonly Seen, Rarely Recognized, and Poorly Understood Diagnosis.

INTRODUCTION: Unspecified functional bowel disorder (FBD-U) is a Rome IV diagnosis of exclusion and occurs when patients report bowel symptoms but do not meet the criteria for other functional bowel disorders (FBD; irritable bowel syndrome [IBS], functional constipation [FC], functional diarrhea [FDr], or functional bloating). Previous research suggests that FBD-U is as/more common than IBS. METHODS: One thousand five hundred one patients at a single-center tertiary care center completed an electronic survey. Study questionnaires included Rome IV Diagnostic Questionnaires, anxiety, depression, sleep, health care utilization, and bowel symptom severity measures. RESULTS: Eight hundred thirteen patients met Rome IV criteria for a FBD and 194 patients (13.1%) met criteria for FBD-U, representing the second most common FBD after IBS. Severity of abdominal pain, constipation, and diarrhea were lower in FBD-U compared with other FBD, whereas health care utilization was similar among the groups. Scores on measures of anxiety, depression, and sleep disturbances were similar in FBD-U compared with FC and FDr but were less severe than IBS. Between 25% and 50% of patients with FBD-U did not meet Rome IV criteria for other FBD due to timing of onset of the target symptom (e.g., constipation for FC, diarrhea for FDr, and abdominal pain for IBS). DISCUSSION: FBD-U, by Rome IV criteria, is highly prevalent in clinical settings. These patients are not represented in mechanistic studies or clinical trials for not having met Rome IV criteria for other FBD. Making future Rome criteria less stringent would minimize the number fulfilling criteria for FBD-U and maximize the true representation of FBD in clinical trials.

Gastroenterologist Primer: Endometriosis for Gastroenterologists.

BACKGROUND AND AIM: A comprehensive understanding of endometriosis and its common gastrointestinal presentations are critical for gastroenterologists to ensure appropriate and timely screening and diagnosis. Endometriosis is a common inflammatory disease that frequently presents with gastrointestinal symptoms overlapping with irritable bowel syndrome (IBS) and other gastrointestinal disorders. Many endometriosis patients first present to a gastroenterologist or generalist, which may prolong the time to diagnosis and appropriate care. METHOD AND RESULTS: This review describes the current literature on endometriosis presentation, overlap with gastrointestinal conditions, and standard diagnostic and treatment options for gastroenterologists to consider. For appropriate and swift treatment, gastroenterologists must consider an endometriosis diagnosis in females of menstruating age presenting with pain, bloating, altered stools, and non-gastrointestinal symptoms and refer patients for further evaluation.