LOS ANGELES — Even the experts disagree about what tests should be ordered to rule out organic disease in patients presenting with symptoms of irritable bowel syndrome, according to survey results presented at the annual Digestive Disease Week.
Dr. Brennan M. Spiegel and associates at the University of California, Los Angeles, surveyed 27 recognized experts in irritable bowel syndrome (IBS), 53 randomly chosen gastroenterologists from the American Gastroenterological Association, 89 primary care physicians, and 102 nurse-practitioners to determine whether various health care professionals consider IBS to be a diagnosis of exclusion.
Their results suggest that many physicians and other health care professionals are not following practice guidelines issued in 2002 by the American College of Gastroenterology (ACG), which emphasize the importance of assessing IBS symptoms and discourage extensive work-ups for patients who do not have alarming symptoms or findings on physical examination.
Survey respondents were presented with a fictitious patient scenario and asked what tests they would order to establish a diagnosis of IBS. In the vignette, the patient was a 42-year-old woman with a history of loose stools for many years and up to six bowel movements a day. She described crampy, left lower quadrant pain that improved with stool passage. Neither her history nor her physical exam revealed any alarming symptoms.
On that description alone, two-thirds of IBS experts were willing to endorse a diagnosis of IBS, compared with 34% of primary care physicians, 43% of gastroenterologists, and 41% of nurse-practitioners.
IBS experts were in strong agreement that two tests would be warranted to rule out organic disease: a complete blood count and a test for antibodies to celiac sprue. They also agreed on one inappropriate test: a breath test for small-intestine bacterial overgrowth.
“Everything else was uncertain, even among experts, about what to do,” Dr. Spiegel said. Respondents showed “extreme variation” in the additional tests they said they would order, with some advocating a chemistry panel, erythrocyte sedimentation rate, thyroid stimulating hormone, stool white blood cell count, and other tests.
On average, the IBS experts said they would order a total of 2 tests, while gastroenterologists would order 3.9; primary care physicians, 4.1; and nurse-practitioners, 4.3.
The experts, chosen on the basis of their publications and selection for guidelines committees, were also far less likely than other health professionals to say they believed IBS was a diagnosis of exclusion; the rate was 8% of experts, compared with 42% of gastroenterologists and 72% of both primary care physicians and nurse-practitioners.
After adjustment was made for type of health professional, practice type, age, gender, and experience treating IBS patients, the belief that IBS is a diagnosis of exclusion predicted the desire to order 1.6 more tests and spend $364 more on diagnostic testing of the patient in the vignette.
“In general, this disconnect indicates that these guidelines, [which] have been much ballyhooed by the ACG and other groups, either are not being disseminated correctly or simply are not being followed or believed,” Dr. Spiegel said.
An audience member praised the study, saying the findings were “dead on.”
“I think we all realize that the diagnosis of IBS is probably imperfect and fraught with error,” Dr. Spiegel responded.
Interim results of an unrelated study presented at the meeting suggest that if one test is going to be ordered for patients meeting Rome II criteria for diarrhea-predominant or mixed IBS, a celiac disease panel is probably a good choice.
A study from the National Naval Medical Center in Bethesda, Md., Walter Reed Army Medical Center in Washington, and the University of Maryland, Baltimore, attempted to identify organic gastrointestinal findings among 323 patients with IBS who received an extensive array of tests: complete blood count, comprehensive metabolic panel, thyroid function test, erythrocyte sedimentation rate, C-reactive protein panel, inflammatory bowel disease panel, hypolactasia (lactase deficiency) genetic assay, celiac disease panel, and colonoscopy with rectosigmoid biopsies.
A total of 9 of 323 patients, or 2.8%, were diagnosed with organic gastrointestinal disease based on the exhaustive testing. These included four, or 1.2%, with celiac disease; three with inflammatory bowel disease; one with malignancy; and one with sigmoid volvulus.
The only test that identified significantly more disease in IBS patients than in 241 controls was the celiac sprue test, reported Dr. Brooks D. Cash, director of clinical research and a gastroenterologist at the National Naval Medical Center.