Gulf War Digestive Health Study
Condition: Irritable Bowel Syndrome; Small Intestinal Bacterial Overgrowth
MeSH terms: Irritable Bowel Syndrome; Syndrome
Study type: Interventional

Summary: 
      The purposes of this study are to estimate the burden of disease due to chronic
      gastrointestinal illness in PG veterans, to evaluate whether Small Bowel Bacterial Overgrowth
      (SBBO) is associated with chronic diarrhea in PG veterans, and to determine whether
      eradication of SBBO reduces symptoms of chronic diarrhea, abdominal pain and bloating in PG
      veterans.
    

Detailed description: 
      Approximately 700,000 United States military personnel were deployed in the first Persian
      Gulf (PG) War. Several months after their return, up to 25% of Veterans had persistent
      symptoms which they suspected were related to their military service in the Gulf. Among the
      most frequent were gastrointestinal symptoms such as loose stools, excessive gas and
      abdominal pain. These symptoms are typical of diarrhea-predominant irritable bowel syndrome
      (IBS).

      The cause of IBS is not known; speculated mechanisms include altered GI motility, bacterial
      overgrowth, visceral hypersensitivity and psychological stress. Another proposed mechanism
      relates to the fact that up to one third of patients with IBS describe the onset of their
      symptoms following acute gastroenteritis. This is called post-infective IBS (PI-IBS). How
      acute gastroenteritis leads to persistent GI symptoms of IBS is not known. A limited amount
      of data suggests that patients with IBS may have an imbalance in their gastrointestinal
      microflora. Several studies indicate that small bowel bacterial overgrowth is more common in
      individuals with IBS. Symptoms of SBBO are similar to diarrhea-predominant IBS and include
      chronic diarrhea, bloating and abdominal pain.

      More than 50 percent of military personnel developed acute gastroenteritis while on duty in
      the Gulf. Most of them who reported symptoms of IBS had an acute onset which occurred in
      association with an episode of acute gastroenteritis during their tour of duty. Other
      travelers are known to be colonized by new micro-organisms during travel to foreign
      countries. This acquisition is thought to be related to a change in diet. The natural history
      of this change in bowel flora, in part, depends on host factors and can persist for months
      after travel abroad. It seems likely, that PG veterans with persistent diarrhea and a
      negative work-up for known GI diseases have PI-IBS. No study in the past has evaluated the
      role of SBBO in causing chronic GI symptoms in PG Veterans. Furthermore, soldiers involved in
      combat are exposed to a highly stressful environment, perhaps making them more susceptible to
      persistent symptoms.

      We hypothesize that PG veterans with chronic GI symptoms have symptoms of diarrhea
      predominant IBS and this is caused by SBBO due to a change in microflora during deployment in
      the Persian Gulf and that it is predisposed to by the stress of combat. Intestinal
      microflora, once altered, is known to be relatively stable; once mucosal damage occurs it may
      become permanent.

      Objectives Objective # 1: Estimate the burden of disease due to chronic gastrointestinal
      illness in PG veterans.

      Hypothesis:

      i. The prevalence of GI symptoms is high in PG veterans. ii. The prevalence of IBS is higher
      in veterans who report acute gastroenteritis during the period of deployment.

      iii. PG Veterans with IBS have a lower IBS related QOL

      Objective # 2: Evaluate whether SBBO is associated with chronic diarrhea in PG veterans.

      Hypothesis i. SBBO is more common in PG veterans than non deployed veterans. ii. SBBO is more
      common in PG veterans with diarrhea-predominant IBS vs. those without.

      Objective: # 3: Determine whether eradication of SBBO reduces symptoms of chronic diarrhea,
      abdominal pain and bloating in PG Veterans.

      Hypothesis:

      i. Treatment with rifaximin, a non-absorbable antibiotic, will improve symptoms and QOL in
      Veterans with SBBO.
    

Intervention name(s): Placebo; Rifaximin
Intervention type(s): Drug; Drug
Intervention description(s): orally two times per day for 14 days; 550 mg orally two times per day for 14 days
Other intervention name(s): Inactive pill; Xifaxan
Intervention MeSH terms: Rifaximin
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Irritable Bowel Syndrome; Diarrhea; Gulf War; Veterans; Small intestinal bacterial overgrowth (SIBO)