IBS is a prevalent and expensive condition that can significantly impair health-related quality of life (HRQOL) and reduce work productivity. Epidemiological studies suggest that 7 percent to10 percent of people worldwide have IBS.
Community-based studies indicate that the subgroup of IBS patients with a mixture of diarrhea and constipation symptoms (IBS-M) occurs more commonly than those with predominantly diarrhea (IBS-D) or constipation (IBS-C), and that switching among subtype groups may occur over time. IBS is 1.5 times more common in women than in men. IBS is more common in lower socioeconomic groups and more commonly diagnosed in patients younger than 50 years. IBS patients make more visits to their physicians, undergo more diagnostic tests, prescribed more medications, miss more workdays, have lower work productivity, are hospitalized more frequently, and account for greater overall direct costs than patients without IBS. Resource utilization is highest in patients with severe symptoms, and poorer HRQOL.
Defining IBS
IBS is defined by the presence of abdominal pain or discomfort that occurs in association with altered bowel habits over a period of at least three to six months. Individual symptoms have limited accuracy for diagnosing IBS and the disorder should be considered as a symptom complex. In clinical research and to a lesser degree clinical practice, IBS is defined by symptom-based criteria such as Kruis, Manning or Rome I, II, or III criteria.
It is widely accepted that the presence of "alarm features" identifies a population of patients in whom the likelihood of organic disease is greater. Unfortunately, the overall diagnostic accuracy of alarm features is disappointing. Rectal bleeding and nocturnal pain offer little discriminative value in separating patients with IBS from those with organic diseases. Although anemia and weight loss have poor sensitivity for organic diseases, they offer reasonably good specificity. As such, in patients who fulfill symptom-based criteria of IBS, the absence of selected alarm features, including anemia, weight loss and a family history of colorectal cancer, inflammatory bowel disease (IBD) or celiac disease, should reassure the clinician that the diagnosis of IBS is correct.
Diagnostic Testing in IBS
Because of the low likelihood of uncovering organic diseases, routine diagnostic testing with complete blood count, serum chemistries, thyroid function studies, stool for ova and parasites, and abdominal imaging should not be routinely performed in patients with typical IBS symptoms and no alarm features. Routine serologic screening for celiac sprue should be pursued in patients with IBS-D and IBS-M. Lactose breath testing can be considered when lactose maldigestion remains a concern despite dietary modification.
Currently, there are insufficient data to recommend breath testing for small intestinal bacterial overgrowth in IBS patients. Because of the low pre-test probability of Crohn's disease, ulcerative colitis, and colonic neoplasia, routine colonic imaging is not recommended in patients under the age of 50 years with typical IBS symptoms and no alarm features. Colonoscopic imaging should be performed in IBS patients with alarm features to rule out organic diseases and in those over the age of 50 years for the purpose of colorectal cancer screening. When colonoscopy is performed in patients with IBS-D, obtaining random biopsies can be considered to rule out microscopic colitis.
Treatment of IBS
In general, treatments for IBS are directed towards patient's predominant symptoms. There are a wide variety of available therapies many of which improve individual IBS symptoms. Only a small number of therapies have been shown to be of benefit to the global symptoms of IBS.
Fiber is the most widely recommended treatment in patients with IBS. Psyllium hydrophilic mucilloid (ispaghula husk) is moderately effective for the treatment of IBS symptoms. A single study reported improvement with calcium polycarbophil. Bran is no more effective than placebo in the relief of global symptoms of IBS and cannot be recommended for routine use.
The antidiarrheal agent loperamide is no more effective than placebo in the treatment of pain, bloating or global symptoms of IBS. However, loperamide is an effective agent for the treatment of diarrhea, reducing stool frequency and improving stool consistency in IBS patients. There is currently little safety and tolerability data on loperamide.
No randomized controlled trials have been reported on the effect of laxatives (eg. milk of magnesia, bisocodyl, senna) in patients with IBS.
Antispasmodics are a heterogeneous group of compounds which are thought to exert their beneficial effects in IBS patients by relaxing gut smooth muscle. Certain antispasmodics (hyoscine, cimetropium, and pinaverium) may provide short-term relief of abdominal pain/discomfort in IBS. Evidence for long-term efficacy is currently not available. Evidence for safety and tolerability of the antispasmodics are limited—these agents should be used cautiously in the elderly.
The 5-HT4 receptor agonist tegaserod has proven more effective than placebo at relieving global IBS symptoms in female IBS patients with constipation and IBS patients with mixed bowel habits. The most common side-effect of tegaserod is diarrhea. A small number (0.11 percent) of cardiovascular events (myocardial infarction, unstable angina, or stroke) were reported among patients who had received tegaserod in clinical trials. Because of this, tegaserod was withdrawn from the U.S. market in April of 2008. Other 5-HT4 agonists are currently undergoing testing as treatments for IBS-C.
The 5-HT3 receptor antagonist alosetron is more effective than placebo at relieving global IBS symptoms in male and female IBS patients with diarrhea predominance. Potentially serious side effects including constipation and colon ischemia occur more commonly in patients treated with alosetron compared with placebo. Because of these potentially serious side effects, alsoetron is only available through a restricted access program for women with severe IBS-D who have not responded to conventional medical therapies.
New Patient Tools for IBS
Because of the difficult diagnosis of IBS, as well as patient uncertainty about the disease, recently, the American College of Gastroenterology (ACG) announced the availability of two new interactive tools aimed at helping IBS sufferers. The first tool—also called "The IBS Test"—is intended to help undiagnosed individuals recognize the signs and symptoms of IBS. The second—called the "IBS Treatment Matrix"—is based on the aforementioned data to help in analyzing IBS treatment options. This tool offers basic information as well as graded recommendations on 16 categories of IBS therapies.
Over the last 20 years, a number of scientific studies have demonstrated that people with IBS tend to have higher levels of sensitivity in the intestines compared to individuals who do not have IBS.
The IBS Test interactive tool allows individuals to quickly distinguish whether they are experiencing the most common symptoms associated with IBS through a series of easy-to-answer questions. Capturing this data enables a patient to have a more comprehensive conversation with their doctor concerning their unique symptoms.
Once diagnosed, IBS can still be challenging to treat. As outlined above, there are many treatment options to consider—from therapies which act on bowel symptoms to new agents and alternatives including antidepressants, antibiotics and even probiotics. While there is a large number of choices for patients and physicians, few treatments have proven effective at improving the global symptoms of IBS in well-designed clinical trials.
The IBS Treatment Matrix provides an at-a-glance overview of all currently available IBS treatment options, plus evidence supporting the safety and efficacy of those options, enabling IBS patients and their physicians to consider all the possible alternatives while formulating a treatment plan. They provide a good reference point for educating the patient about the symptoms and potential treatment options.
To help people with IBS gain a better understanding of the condition and how it's diagnosed, as well as what foods may trigger symptoms, and the over-the-counter and prescription treatments available, Chey offers these seven tips to help separate IBS fact from fiction.
Seven Common Myths – and Facts – About IBS
1.MYTH: IBS is psychosomatic
FACT: For many years, physicians believed IBS was a psychological condition – it only existed in the patient's head. While some patients with IBS experience depression or anxiety, it is likely that psychological distress or stress worsen IBS, but may not be the primary cause of it.
2. MYTH: IBS only affects young women
FACT: Although IBS does tend to occur more frequently in women, Chey says, "it's important that people know that there are many men diagnosed with IBS, and it also affects the elderly. In fact, there's some early evidence to suggest that IBS affects 8 percent to 10 percent of older individuals."
3. MYTH: IBS is not an important condition
FACT: "Many physicians believe that IBS is not an important condition because it does not affect a person's lifespan," says Chey. While that may be the case, IBS can significantly impact a person's quality of life and ability to function on a day-to-day basis, and should be taken seriously by doctors and patients alike.
4. MYTH: IBS is related to lactose intolerance
FACT: About a quarter of patients with IBS are also lactose intolerant. However, Chey notes that about a quarter of the general population who don't have IBS are lactose intolerant as well. So, he says, while lactose intolerance may play a role in some patients, it is not the cause of symptoms in the vast majority of patients with IBS.
5. MYTH: IBS means a lifetime of bland food
FACT: "A lot of patients with IBS end up on these very bland diets, and I think most of the time it is not justified," says Chey. Instead, Chey has his patients keep a diary to record all of the food that they eat, and any symptoms they may experience.
"At the end of a two-week period, it's possible to get a fairly good idea about whether there are specific trigger foods associated with the onset of symptoms. Those foods then can be easily eliminated from a patient's diet." Certain foods, however, such as fatty foods, milk products, chocolate, alcohol, caffeine and carbonated drinks are more likely to aggravate symptoms in some IBS patients.
6. MYTH: IBS cannot be accurately diagnosed
FACT: Contrary to what some physicians believe, Chey says most patients do not need a lot of medical tests to be diagnosed with IBS. "Identifying the presence of persistent or recurrent abdominal pain in association with altered bowel habits, and excluding warning signs (e.g., new symptoms occurring after age 50, GI bleeding, unexplained weight loss, nocturnal diarrhea, severe or progressively worse symptoms or a family history of colon cancer, inflammatory bowel disease, colon cancer or celiac disease), is enough to accurately diagnose IBS in most patients."
7. MYTH: There are no good treatment options for IBS
FACT: Not true, says Chey. With effective counseling, dietary and lifestyle intervention, and use of over-the-counter or prescription medications, IBS can be effectively managed. "Treating infrequent or mild symptoms with over-the-counter medication is effective for most patients," he says. "If symptoms are persistent, however, it's important to see your physician because the excessive use of over-the-counter medications can actually lead to more gastrointestinal symptoms." If symptoms do not improve with changes in diet and lifestyle, or over-the-counter medications, prescription medications are available for people with IBS.
William D. Chey, MD, FACG, AGAF, is professor of medicine and director of the GI Physiology Laboratory for the University of Michigan Health System.
