Who gets irritable bowel syndrome and does seeing a gastroenterologist affect its course ?

HOW COMMON IS THIS PROBLEM? Prevalence rates of IBS over the past two decades have ranged from 9% to 23%, depending on the nature of the study performed (Table 1). For instance, in populationbased surveys, rates have been 9% (United States householder’s survey [1]) and 13% (Australia [2]). Rates have been as high as 23% in family practice settings in the United Kingdom (3). The study of prevalence rates through a doctor’s office includes a selection bias of subjects who present to the doctor and may bias the data toward higher rates. Nearly 50% of the population may have IBS-type symptoms but not meet the Manning or Rome criteria for IBS (Table 1).

United Kingdom (5) and one study was a United States householder survey (4).Other studies suggested that having abdominal pain (Olmsted County, Minnesota [6,7], United Kingdom [3] and Australia [2]) increased the likelihood of medical attention, and this association correlated with severity or intensity of pain (Table 2).

WHAT PREDISPOSES PEOPLE TO IBS?
There is an emerging consensus that patients with IBS may be genetically predisposed and may have suffered an important intestinal insult (ie, a past infection).There is a widely held view that these patients are more likely to have endured major psychosocial trauma, or currently are enduring major chronic life stress or may simply be more likely to have concurrent psychiatric disorders.No discreet cause of IBS has ever been discerned, and it is extremely unlikely that a single cause will ultimately account for all cases.In fact, because there are several clinical subsets of IBS (diarrhea-predominant, constipation-predominant, mixed bowel habit pattern, pain-predominant), there are likely several etiological pathways that lead to IBS.For some patients there may be a sensorineural disturbance at a peripheral (gut) or central level.For other patients there may be primary intestinal motor disturbances.For some patients no neurophysiological disturbances may be discerned.IBS is not an inflammatory disorder, but the likelihood that a prior inflammatory event occurred in some patients is plausible.
Investigators have pursued studies regarding life stress, psychiatric diagnoses and sexual abuse.There are data suggesting that IBS patients are more likely to have been sexually or physically abused at some time in their lives than patients with organic gut disorders or no disorders at all.Because much of the sexual abuse data come from specialized centres, it is hard to know how much the data reflect the general population.For subjects who complete population surveys, it is hard to know whether patients who have been sexually abused would be more or less likely to answer those questions.Past sexual abuse is common in society and, thus, its role as a predisposing factor in IBS must be carefully weighted (Table 3).
One type of IBS that may be short lived is postinfectious IBS.In a study performed through travel clinics in Winnipeg in 1999 (8), it was found that the incidence of new onset IBS post-traveller's diarrhea was as low as approximately 2% in people who were completely healthy before travel.Up to 6% of people may develop new gut symptoms that, as a whole, do not qualify under Manning or Rome criteria as IBS.These numbers may seem to be small; however, they may contribute a significant burden on the population, considering the extent of travel to areas with high risks of associated traveller's diarrhea, and considering that subjects often travel recurrently, not simply once in a lifetime.

Bernstein
Can J Gastroenterol Vol 15 Suppl B October 2001 6B  It has been suggested that the depth of the physicianpatient interaction and the time that the physician spends discussing the patient's symptoms and concepts regarding IBS should enhance patient outcome.Ilnyckyj et al (9) undertook a study in Winnipeg through the offices of two academic-based and two private practice-based gastroenterologists to determine the impact of gastroenterology consultation on health care utilization patterns and the well-being of the patient when followed up over a two-year period.The authors' preliminary data reveal that, after a structured gastroenterology consultation, the number of office visits for gastrointestinal-related complaints and for psychiatric complaints significantly diminishes in the first year postconsultation, whereas all other visit types did not change.Data on well-being are forthcoming.

Irritable bowel syndrome
Can J Gastroenterol Vol 15 Suppl B October 2001 7B

TABLE 3 Literature review of abuse and gastrointestinal illness
Abuse history, psychiatric disturbance and medical symptoms are significantly associatedAbuse history is more commonly reported by women Abuse history is more common in referral practice than in primary carePatients with functional gastrointestinal disorders report abuse more frequently than patients with organic disorders Abuse history is associated with an increased tendency to seek health care and poorer health status (psychological dysfunction, symptom reporting, more frequent surgery)Patients' physicians are usually unaware of the history of abuse Data from reference 5