American College of Gastroenterology Monograph on the Management of Irritable Bowel Syndrome and Chronic Idiopathic Constipation

Abstract

Irritable bowel syndrome (IBS) and chronic idiopathic constipation ((CIC) also referred to as functional constipation) are two of the most common functional gastrointestinal disorders worldwide. IBS is a global problem, with anywhere from 5 to 15% of the general population experiencing symptoms that would satisfy a definition of IBS (1,2). In a systematic review on the global prevalence of IBS, Lovell and Ford (1) documented a pooled prevalence of 11% with all regions of the world suffering from this disorder at similar rates. Given its prevalence, the frequency of symptoms, and their associated debility for many patients and the fact that IBS typically occurs in younger adulthood, an important period for furthering education, embarking on careers, and/or raising families, the socioeconomic impact of IBS is considerable. These indirect medical costs are frequently compounded by the direct medical costs related to additional medical tests and the use of various medical and nonmedical remedies that may have limited impact. CIC is equally common; in another systematic review, Suares and Ford (3) reported a pooled prevalence of 14%, and also noted that constipation was more common in females, in older subjects, and those of lower socioeconomic status (3). Chronic constipation has also been linked to impaired quality of life (4), most notably among the elderly (5). Neither IBS nor CIC are associated with abnormal radiologic or endoscopic abnormalities, nor are they associated with a reliable biomarker; diagnosis currently rests entirely, therefore, on clinical grounds. Although a number of clinical definitions of both IBS and CIC have been proposed, the criteria developed through the Rome process, currently in its third iteration, have been those most widely employed in clinical trials and, therefore, most relevant to any review of the literature on the management of these disorders. According to Rome III, IBS is defined on the basis of the presence of: Recurrent abdominal pain or discomfort at least 3 days/month in the past 3 months associated with two or more of the following: Improvement with defecation Onset associated with a change in frequency of stool Onset associated with a change in form (appearance) of stool These criteria should be fulfilled for the past 3 months with symptom onset at least 6 months before diagnosis (6). Rome III defines functional constipation as: the presence of two or more of the following: Straining during at least 25% of defecations Lumpy or hard stools in at least 25% of defecations Sensation of incomplete evacuation for at least 25% of defecations Sensation of anorectal obstruction/blockage for at least 25% of defecations Manual maneuvers to facilitate at least 25% of defecations (e.g., digital evacuation, support of the pelvic floor) Fewer than three defecations per week Furthermore, loose stools are rarely present without the use of laxatives and there are insufficient criteria for IBS. Again, these criteria should be fulfilled for the past 3 months with symptom onset at least 6 months before diagnosis (6). In Rome III, IBS is subtyped according to predominant bowel habit as IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), mixed type (IBS-M), and unclassified (IBS-U). The definition of bowel habit type is, in turn, based on the patient’s description of stool form by referring to the Bristol Stool Scale (7). The recognition that IBS sufferers segregate into subtypes according to predominant bowel habit, together with research findings suggesting that IBS-C and IBS-D may be pathophysiologically distinct entities (8,9,10), led to the development of therapies specifically directed at each of these subtypes. Nonetheless, it is worth noting that symptoms may not be stable over a lifetime and individuals may exhibit one IBS subtype during a period, and then a different IBS subtype during another period in their lives. However, although there is general awareness of the Rome criteria, they are infrequently employed in the assessment of IBS and CIC in clinical practice (11). To provide more “clinician friendly” definitions, as well as to permit inclusion of studies that predated the Rome process, American College of Gastroenterology Task Forces suggested the following definitions in prior systematic reviews: IBS is defined by: abdominal discomfort associated with altered bowel habits (12). Constipation is defined as: a symptom-based disorder defined as unsatisfactory defecation and is characterized by infrequent stools, difficult stool passage, or both. Difficult stool passage includes straining, a sense of difficulty passing stool, incomplete evacuation, hard/lumpy stools, prolonged time to stool, or need for manual maneuvers to pass stool. CIC is defined as the presence of these symptoms for at least 3 months (13). It is important to note that the Rome III criteria state that individuals with chronic constipation do not fulfill criteria for IBS, with pain or discomfort bein