As in our prior 2 trials, potential participants with IBS were recruited through general advertisement (flyers, newspapers, public radio, posters on city busses, and targeted mailings to GI clinic patients) in a metropolitan area in the Pacific Northwest (United States). Interested adults were screened over the phone. Eligibility was assessed across the 5-week baseline assessment (initial interview and 4-week diary). During the last 2 weeks of this assessment period, preselected candidate biomarkers were obtained. The criteria for inclusion specified men and women 18–70 years of age. In addition, participants had to have a history of IBS symptoms for at least 6 months prior to their IBS diagnosis and for at least 6 months after their diagnosis by a healthcare provider. They had to meet the Rome-III research criteria.17 Adults age 50 or older had to have a negative colonoscopy, sigmoidoscopy, abdominal ultrasonography, or barium enema. Anyone with a “red flag” symptom (eg, lost 10 lbs without trying, blood in stool - except blood due to hemorrhoids) was referred to their healthcare provider for further evaluation (eg, colonoscopy).
Potential participants were excluded if they were taking the following medications: antibiotics, corticosteroids, daily use of anticholinergics, tricyclic antidepressants, calcium-channel blockers; had a medical history of abdominal surgery (except appendectomy, Cae-sarian section, tubal ligation, laparoscopic cholecystectomy, hysterectomy, or abdominal wall hernia repair); organic GI disease, celiac disease, or a moderate to severe pain condition (eg, low back pain and fibromyalgia); diabetes, current mental health disorders (psychosis, bipolar disorder, or moderate to severe depressive episodes, recent suicide attempt or drug or alcohol abuse or dependence); cardiac valve or conduction defects, immune-compromised disorders (eg, autoimmune conditions) or women who were pregnant, breast feeding, or planning to get pregnant in the next year (Figure).