Irritable bowel syndrome (IBS) is common, occurring worldwide in males and females of all age-groups. Prevalence figures vary, owing partly to the lack of definitive diagnostic criteria. On the basis of information compiled from diagnostic and symptom-associated surveys, prevalence ranges from 2.9% to 20%. A meta-analysis conducted by the ACG task force determined a rate of about 10% to 15%. Data from the Second National Health and Nutrition Examination Survey (NHANES II), gathered from 1976 to 1980, revealed that 4.7 million people in the US reported “spastic colon” (another term for IBS) or “mucous colitis” (mucus in the stool is common in patients with IBS). Rates of IBS in females in the US range from two to four times that of males, depending on the reference study. Whites have a rate of IBS 5.3 times that of African-Americans.
These findings are supported by the results of the National Ambulatory Medical Care Survey (NAMCS), with results for 1975, 1980 to ’81, and 1985 indicating that women were more than twice as likely as men to present with symptoms of irritable bowel syndrome (IBS). Women between ages 15 and 24 also show a sharp increase in diagnosis, without a corresponding peak for males. For many women, the initial presentation coincides with menarche; this, along with perimenstrual symptoms, suggests a hormonal association.More than 50% of patients with IBS first present to a physician before age 45. Sandler reported that rates increased between ages 25 to 44 and peaked at ages 45 to 64.
Functional bowel disorders account for a large portion of outpatient primary and specialty care practices and are associated with considerable morbidity and health care costs. Irritable bowel syndrome (IBS) accounts for 12% of primary and 28% of tertiary gastroenterology practices. Overall health care use is also greater among patients with IBS. Drossman et al reported that persons with IBS saw physicians 1.64 times for gastrointestinal (GI) complaints in the year evaluated and 3.88 times in that same year for nongastrointestinal complaints. This is compared to frequencies of 0.09 and 1.77 visits to a physician, respectively, in the previous year for patients without IBS. Irritable bowel syndrome (IBS) is reportedly responsible for 2.4 to 3.5 million physician visits and more than 2.2 million prescriptions per year in the US.
Of the population affected by IBS, 50% to 70% of those who experience symptoms may not visit a physician. A group of 301 apparently healthy individuals were evaluated for functional gastrointestinal (GI) disorders. In this sample, most of whom had not sought medical care, typical irritable bowel syndrome (IBS) symptoms were present in 13.6%, colonic pain in 7%, and painless diarrhea in 3.7%.
IBS has a significant negative impact on quality of life (QOL). Patients with chronic gastrointestinal (GI) complaints had some of the lowest QOL scores compared with patients with other chronic illnesses. The impact on QOL may correlate less with bowel symptom severity and more with psychological status of the patient.
Conservative estimates place direct costs associated with irritable bowel syndrome (IBS), exclusive of outpatient medications, at more than $25 billion. One study calculated that the yearly direct medical costs for patients with IBS were $742 versus $429 (1992 dollars) for patients with no GI symptoms. Absenteeism from work is estimated to be about three times greater for IBS patients. Decreased work productivity, lost work days, and sick time use are higher among irritable bowel syndrome (IBS) sufferers, and are estimated to account for 75% of the total IBS economic burden.