One of the questions that most individuals diagnosed with irritable bowel syndrome (IBS) understandably have about their disorder is what will happen to it over time. Will it go away, continue for years and years, or even get worse or turn into another more dangerous medical problem? Several research studies have provided answers to this question in general terms. One additional study1 was added to that literature a couple of months ago — a large 10-year national population survey from Iceland — and it further reinforces a relatively consistent picture of what most typically happens to IBS in the course of time.
IBS goes away in as many as half or more of patients over several years.
By definition, IBS is a chronic health problem. The current Rome III diagnostic criteria require that the symptoms must have been present for at least 6 months for it to be diagnosable. However, research indicates that in a lot of patients the disorder disappears over time. In 2004, El-Serag and colleagues published a review of 14 studies with data about this published up to that point in time2. They found that across those studies, 2–18% of patients were reported to develop worse IBS symptoms over time, 30–50% of patients remained unchanged, and the rest either improved or became symptom-free. Some of these studies were quite small, though (as few as 13 IBS patients!), and they were all studies on clinic patients, which might not give a good idea of IBS in the general population. Moreover, the follow-up period was not always very long (from 6 months to 6 years).
However, four large health surveys of the general population in four different countries have also investigated (among other things) what happens to IBS across time, and have covered longer periods. The earliest of these was a Swedish study published in 20013, which found that of people who met IBS symptom criteria in their initial survey, 55% still had IBS at seven-year follow up. The majority of those who no longer met IBS criteria only had minor or no bowel symptom. A British study4. found that two-thirds to three-quarters of patients still had IBS 10 years later. A U.S. study5. in Minnesota found that more than half (55.1%) of individuals who met IBS criteria no longer qualified as having the disorder when surveyed again 12 years later, and about one in every three was free of bowel symptoms at that follow-up point. Finally, the conclusions from the newest population sample, the Icelandic study published in March of this year1, were almost identical to those of the Minnesota study in their 10-year follow-up: 55.6% of individuals with IBS no longer met symptom criteria, and a third were symptom-free.
When we take the results of all of these studies together, it is clear that a lot of people get over their IBS in a course of several years, and a substantial minority becomes free from the bowel symptoms altogether. Even though the course varies a lot, IBS symptoms are generally more likely to mellow or fade gradually over time rather than to get worse. However, this fading seems to typically happen quite slowly. Our research team looked at this as a part of one of our long-term research studies that is still ongoing. I presented the preliminary findings at Digestive Disease Week in 20086. We evaluated the symptoms of 124 IBS patients in our research laboratory, and re-assessed their symptoms 1-3 years later. We found that the overall severity of IBS (measured on the validated IBS-SS scale that summarizes symptoms into a single index score) was on the average 1.0% lower at 1 year follow-up, 5.5% lower after two years, and 22.5% lower after 3 years.
IBS is rarely found to be something else instead, and does not develop into more dangerous disease.
Another aspect to wondering about how IBS will turn out is the question of whether the problem that is labeled IBS by the doctor turns out to really be something else eventually, and also whether IBS evolves into a more physically harmful disease over time. The evidence indicates that this is generally not the case. Assuming that the diagnosis is competently made, research shows that the odds are overwhelmingly that a person with IBS will not be found later to have something else in stead. The systematic review by El-Serag and colleagues mentioned earlier2 found that only 2-5% of patients received an organic GI diagnosis instead (that is, not a functional problem like IBS) at follow up 6 months to 6 years later. Furthermore, Chey and colleagues7 recently used colonoscopies to search for evidence of organic/structural problems such as polyps, lesions or cancer in 466 IBS patients and 451 healthy individuals with no IBS symptoms. They found no significant differences in physical abnormalities in the bowels of the two groups. This confirms that IBS is generally a sound diagnosis and that the symptoms are rarely explained by other things going on in the gut (even though that is always prudent to keep in mind as a possibility in individual cases – especially if the symptom pattern changes or other troubling symptoms start). In our own sample of 124 IBS patients whom we followed up with after 1-3 years6, only four had been diagnosed with something else that could explain their bowel symptoms during that period (2 bacterial infections; 1 possible Crohn’s disease; 1 colonic atonia). That amounts to 3 percent of people in our sample, which is right in line with results from other studies.
In summary, the available research evidence to date indicates that IBS diagnosis almost always identifies the problem correctly, and that it is a disorder that gets significantly milder over time and goes away for the majority of patients who suffer from it, even though it may take some years to do so. What is currently sorely missing in our current the state of knowledge about the long-term fate of IBS, however, is information on why IBS goes away in the many people for whom it disappears. There are hardly any data in the studies published to date that give us good clues about what factors (such as particular treatments, lifestyle changes or specific self-management approaches), if any, faciliated making IBS disappear permanently. This needs to be examined systematically in future studies.
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