Experience with anxiety and depression treatment studies: implications for designing irritable bowel syndrome clinical trials

This report highlights various considerations regarding the potential effects of concurrent psychiatric conditions and a history of abuse in patient volunteers for clinical trials in irritable bowel syndrome (IBS). Even though many studies have used psychological rating scales to assess personality and psychological traits of patients with IBS, the prevalence of the different psychiatric diagnoses (i.e., categorical assessment) in patients with IBS has only recently been assessed systematically. Recent studies of treatment-seeking patients have indicated that the majority of individuals (50% to 90%) who seek treatment for IBS have a lifetime history or currently have one or more common psychiatric conditions: major depressive disorder, generalized anxiety disorder, panic disorder, social phobia, somatization disorder, and posttraumatic stress disorder. Traditional clinical wisdom is that the presence of a psychiatric disorder increases the likelihood that an IBS patient will seek treatment. However, recent data suggest that IBS and psychiatric disorders are associated regardless of treatment-seeking status. Patients with psychiatric disorders should be included in clinical IBS studies, because this reflects the actual patient population. Extrapolating from the psychiatric literature, inclusion of patients with IBS with mild to moderate anxiety or depression is warranted.