Irritable Bowel Syndrome in the United States: Prevalence, Symptom Patterns and Impact

A. P. S. Hungin; L. Chang; G. R. Locke; E. H. Dennis; V. Barghout


Aliment Pharmacol Ther. 2005;21(11):1365-1375. 

In This Article


From approximately 14 000 initial telephone contacts, a total of 5009 screening interviews were conducted; all questions in this section were related to general health. Among these, 708 individuals were identified as having current IBS (any diagnostic criteria) and, from this group, 318 individuals participated in the second phase of the questionnaire (366 individuals either did not want to take part in the second phase of the questionnaire or did agree but were not available when contacted).

Overall 708 individuals (14.1% of total screened) were identified as having current IBS [medically diagnosed ( n = 166; 3.3%) or met any diagnostic criteria (not medically diagnosed; n = 542; 10.8%)]. Results from this questionnaire are shown in Table 1 .

In general, medically diagnosed IBS patients reported a greater prevalence of individual IBS symptoms. The Manning criteria identified all current IBS sufferers (100%); the Rome I criteria identified 73% and the Rome II criteria identified 62%. Thus, only partial overlap of the IBS diagnosis was seen across these diagnostic criteria. The Rome II criteria appeared to be the most restrictive set. Of those individuals who had been medically diagnosed with IBS, 4% were deemed to have IBS-C compared with 21% with IBS-D. In those not medically diagnosed, these percentages were 15% and 21%, respectively. Most individuals with IBS (74% of those medically diagnosed and 63% not medically diagnosed) reported alternating symptoms of constipation and diarrhoea (IBS-A). When IBS sufferers were asked to categorize themselves according to these three subgroups, only approximately one-third of individuals medically diagnosed and not medically diagnosed with IBS defined themselves as having IBS-A (33% and 27%, respectively) compared with IBS-C (17% and 30%, respectively) and IBS-D (45% and 29%, respectively).

Overall, the peak ages for current IBS symptoms were between 25 and 54 years (67.3% of IBS total; Table 1 ). IBS was more common in women than men (64% vs. 36%, respectively), particularly among those who had been medically diagnosed with IBS (81.3% vs. 18.7%, respectively). The highest prevalence of IBS was seen in working women, with a prevalence of 21% (5% medically diagnosed, 16% not medically diagnosed).

Current IBS sufferers (both medically diagnosed and not medically diagnosed) were more likely to have suffered from other GI disorders of function (previously diagnosed by a doctor) compared with non-IBS sufferers. IBS sufferers were twice as likely to suffer from gastro-oesophageal reflux disease (GERD; 22% vs. 10%, P < 0.001) compared with non-IBS sufferers.

Results of the second phase of this study confirmed that IBS is a chronic disorder, with 16% of current IBS sufferers being medically diagnosed with the condition in the previous 12-month period, 8% in the previous 13-24 months, 26% in the previous 2-5 years and 14% 6-10 years ago. Overall, one-third of current IBS sufferers had had IBS for more than 10 years.

Although respondents had IBS for considerable periods of time, IBS symptoms remained fairly constant over time with 73% of medically diagnosed IBS sufferers reporting that their symptoms had never changed. Only 22% of current IBS sufferers reported some degree of symptom improvement since the screening interview. Current IBS sufferers typically experienced symptoms for an average of 8.1 days/month and reported a wide range of symptoms, with abdominal pain/discomfort being the most commonly reported (90%; Figure 1). The majority (71%) described their overall IBS symptoms as fairly or very painful. On each day with current symptoms (designated as a 'suffering day'), respondents with IBS had an average of 2.4 episodes of IBS. These episodes varied in duration but more than half (52%) of current sufferers experienced episodes more than 60 min in duration. More than half (64%) of individuals with current IBS symptoms believed that an episode of IBS was triggered by a certain food or drink while 30% cited stress as the trigger.

Symptoms suffered by current irritable bowel syndrome sufferers (medically diagnosed and not medically diagnosed).

There appeared to be a gender difference in the reporting of IBS-related symptoms in current IBS sufferers. Women were more likely to report constipation, bloating, trapped wind, swollen tummy, tightness of clothing and tiredness. There were no differences in prevalence of abdominal pain, diarrhoea and heartburn between men and women with IBS.

Responses from current IBS sufferers (medically diagnosed and not medically diagnosed) indicate that IBS negatively impacted upon a wide range of daily activities. Work productivity, particularly the ability to concentrate, and time management, was significantly affected in respondents with IBS compared with individuals without IBS (Figure 2; P = 0.01). The proportion of men and women reporting an impact was not significantly different.

Impact of irritable bowel syndrome on work activities.

In the 12 months prior to the survey, IBS sufferers had more time off work, spent more days in bed and cut down on usual activities on more days compared with non-IBS sufferers. Nearly one-quarter of IBS respondents worked fewer hours, 11% missed work and 67% felt less productive when at work because of their symptoms. Two-thirds of current IBS sufferers had cut back on the number of overall activities during the previous 12-month period for an average of 15 days. The average number of days affected by ill health leading to absenteeism was 6.4 vs. 3.0 days (current IBS sufferers vs. non-IBS sufferers). Overall, current IBS sufferers were twice as likely to spend at least 1 day in bed or cut back on usual activities compared with non-IBS sufferers. Nearly one-quarter of current IBS sufferers had missed social engagements.

IBS symptoms also had a significant impact on social well-being and daily social activities among sufferers compared with non-sufferers ( P = 0.01). Undertaking long journeys, going out for a meal and going on holiday were all noted as more of a problem for IBS sufferers than controls (Figure 3a; P = 0.01). In addition, diet and food choice were also adversely affected by current IBS symptoms (Figure 3b; P = 0.01 vs. individuals without IBS). IBS sufferers reported a wide range of effects of symptoms on daily life (≥5 points on a scale of 0 = no impact to 10 = significant impact), in particular many felt they had to be either near a toilet or make frequent trips to the toilet (Figure 4). Again, the proportion of men and women reporting an impact was not significantly different.

(a) Impact of irritable bowel syndrome on social activities. (b) Impact of irritable bowel syndrome on well-being.

Impact of irritable bowel syndrome (IBS) on daily life in current IBS sufferers.

Current IBS sufferers were more likely to perceive themselves as having poor health; compared with 54% of non-IBS sufferers, only 35% of IBS sufferers described themselves as having good health. More than half (57%) of all current IBS sufferers questioned felt that they would have more control over their life without IBS symptoms. An impact of health on relationships was also more evident amongst current IBS sufferers compared with non-IBS sufferers: more IBS sufferers found it difficult to make new friends (46% vs. 40%, P < 0.001) and have physical relationships (52% vs. 41%, P < 0.001), and they felt that their IBS symptoms affected family relationships (48% vs. 40%, P < 0.001).

In general, the attitude towards health and overall quality of life appeared to be affected to a greater extent in medically diagnosed patients than in IBS sufferers who were not medically diagnosed ( Table 2 ).

Current IBS sufferers commonly informed their partner about their condition (68%). Although they also often told other family members (56%) and friends (54%), they were less likely to inform colleagues (22%) or their employer (16%). Most confidants were deemed to be very (44%) or fairly (39%) understanding. Overall, one-quarter of IBS sufferers highlighted that their self-confidence was reduced as a result of IBS; this was particularly evident among the medically diagnosed group (46% vs. 17% of those not medically diagnosed). The majority (87%) of respondents medically diagnosed with IBS believed their IBS to be a real medical condition, compared with only 43% of individuals not medically diagnosed ( Table 2 ). As an indication of desire for effective therapy, nearly half of current IBS sufferers (46%) agreed that they would try 'anything' to alleviate their IBS symptoms.

A primary care doctor was the most common health professional seen by current IBS sufferers (83%); gastroenterologists were the next most commonly consulted group (40%; Table 2 ). Abdominal pain/discomfort was the most common reason for consulting a health professional (28% of consultations), followed by symptom frequency (10%). Current IBS sufferers had seen a doctor or nurse an average of 4.2 times in the past 12 months if medically diagnosed or 1.3 times if not medically diagnosed. More than half (53%) of respondents not medically diagnosed had seen a health professional at some time for their condition. In patients medically diagnosed with IBS, 25% had visited a health professional five or more times before their IBS diagnosis.

More than half (58%) of the current IBS sufferers who had visited their health professional had been prescribed medication and a similar number (57%) received dietary and lifestyle advice ( Table 2 ). The main medications taken were antacid and acid suppression therapy (25%), antidiarrhoeals (22%) and laxatives (11%); the serotonergic agents, tegaserod and alosetron, were not available at the time of the study. Antidepressant/anti-anxiety medication was taken by 1% of participants (5% in the medically diagnosed group and 0% in those not medically diagnosed). Most IBS sufferers regularly used over-the-counter medication (60%) and 47% had altered their diet in an attempt to alleviate their IBS symptoms. Treatments were deemed ineffective for a number of symptoms including constipation (41%), bloating (34%) and trapped wind (31%). Treatments for abdominal pain/discomfort were considered to be fairly effective in 53% of sufferers, although 18% considered them to be not at all effective.


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