title: Chronic Constipation and Constipation-Predominant IBS: Separate and Distinct Disorders or a Spectrum of Disease?
abstract: Rome III diagnostic criteria separate patients with idiopathic chronic constipation into mutually exclusive categories of constipation-predominant irritable bowel syndrome (IBS-C) or functional constipation (FC). However, several experts think that these conditions are not different disorders, but parts of a continuum. To shed light on this issue, we examined studies that compared IBS-C with FC with respect to symptoms, pathophysiologic mechanisms, and treatment response. When the Rome III requirement that patients meeting criteria for IBS cannot also be given a diagnosis of FC is suspended, most patients meet criteria for both, and, contrary to expectation, IBS-C patients have more symptoms of constipation than patients with FC. No symptoms reliably separate IBS-C from FC. Physiologic tests are not reliably associated with diagnosis, but visceral pain hypersensitivity tends to be more strongly associated with IBS-C than with FC, and delayed colonic transit tends to be more common in FC. Although some treatments are effective for both IBS-C and FC, such as prosecretory agents, other treatments are specific to IBS-C (eg, antidepressants, antispasmodics, cognitive behavior therapy) or FC (eg, prucalopride, biofeedback). Future studies should permit IBS-C and FC diagnoses to overlap. Physiologic tests comparing these disorders should include visceral pain sensitivity, colonic transit time, time to evacuate a water-filled balloon, and anal pressures or electromyographic activity from the anal canal. To date, differential responses to treatment provide the strongest evidence that IBS-C and FC may be different disorders, rather than parts of a spectrum.
authors.affiliation: Dr Siah is an associate consultant in the Division of Gastroenterology and Hepatology at the University Medicine Cluster at National University Hospital and Yong Loo Lin School of Medicine at the National University of Singapore in Kent Ridge, Singapore. Dr Wong is an adjunct associate professor of medicine at Yong Loo Lin School of Medicine at the National University of Singapore. Dr Whitehead is a professor of medicine, adjunct professor of obstetrics and gynecology, and director of the Center for Functional Gastrointestinal and Motility Disorders at the University of North Carolina at Chapel Hill in Chapel Hill, North Carolina.
authors.forename: Kewin T H
authors.initials: KT
authors.lastname: Siah
authors.affiliation: Dr Siah is an associate consultant in the Division of Gastroenterology and Hepatology at the University Medicine Cluster at National University Hospital and Yong Loo Lin School of Medicine at the National University of Singapore in Kent Ridge, Singapore. Dr Wong is an adjunct associate professor of medicine at Yong Loo Lin School of Medicine at the National University of Singapore. Dr Whitehead is a professor of medicine, adjunct professor of obstetrics and gynecology, and director of the Center for Functional Gastrointestinal and Motility Disorders at the University of North Carolina at Chapel Hill in Chapel Hill, North Carolina.
authors.forename: Reuben K
authors.initials: RK
authors.lastname: Wong
authors.affiliation: Dr Siah is an associate consultant in the Division of Gastroenterology and Hepatology at the University Medicine Cluster at National University Hospital and Yong Loo Lin School of Medicine at the National University of Singapore in Kent Ridge, Singapore. Dr Wong is an adjunct associate professor of medicine at Yong Loo Lin School of Medicine at the National University of Singapore. Dr Whitehead is a professor of medicine, adjunct professor of obstetrics and gynecology, and director of the Center for Functional Gastrointestinal and Motility Disorders at the University of North Carolina at Chapel Hill in Chapel Hill, North Carolina.
authors.forename: William E
authors.initials: WE
authors.lastname: Whitehead
keywords: Functional constipation; balloon evacuation test; colonic transit time; dyssynergic defecation; irritable bowel syndrome; visceral hypersensitivity