Predisposing factors for positive D-Xylose breath test for evaluation of small intestinal bacterial overgrowth: a retrospective study of 932 patients.
OBJECTIVE
To investigate, in the largest cohort to date, patient characteristics and associated risk factors for developing small intestinal bacterial overgrowth (SIBO) using the D-Xylose breath test (XBT).


METHODS
We performed a retrospective cross-sectional study to analyze patient characteristics who underwent the XBT for evaluation of SIBO. Diagnostic testing with the XBT was performed based on a clinical suspicion for SIBO in patients with symptoms of bloating, abdominal pain, abdominal distension, weight loss, diarrhea, and/or constipation. Consecutive electronic medical records of 932 patients who completed the XBT at the University of Florida between 2005 and 2009 were reviewed. A two-way Analysis of Variance (ANOVA) was used to test for several associations including age, gender, and body mass index (BMI) with a +XBT. A two-way ANOVA was also performed to control for the differences and interaction with age and between genders. A similar analysis was repeated for BMI. Associations between medical conditions and prior surgical histories were conducted using the Mantel-Haenszel method for 2 by 2 contingency tables, stratified for gender. Reported odds ratio estimates reflect the odds of the prevalence of a condition within the +XBT group to that of the -XBT group. P values of less than 0.05 (two-sided) were considered statistically significant.


RESULTS
In the 932 consecutive eligible subjects studied, 513 had a positive XBT. A positive association was found between female gender and a positive XBT (P = 0.0025), and females with a positive test were, on average, greater than 5 years older than those with a negative test (P = 0.024). The mean BMI of positive XBT subjects was normal (24.5) and significantly lower than the subjects with a negative XBT (29.5) (P = 0.0050). A positive XBT was associated with gastroesophageal reflux disease (GERD) (OR = 1.35; 95%CI: 1.02-1.80, P = 0.04), peptic ulcer disease (PUD) (OR = 2.61; 95%CI: 1.48-4.59, P < 0.01), gastroparesis (GP) (OR = 2.04; 95%CI: 1.21-3.41, P < 0.01) and steroid use (OR = 1.35; 95%CI: 1.02-1.80, P = 0.01). Irritable bowel syndrome, independent proton-pump inhibitor (PPI) usage, or previous abdominal surgery was not significantly associated with a positive XBT. No single subdivision by gender or PPI use was associated with a significant difference in the odds ratios between any of the subsets.


CONCLUSIONS
Female gender, lower BMI, steroid use, PUD, GERD (independent of PPI use), and GP were more prevalent in patients with SIBO, determined by a positive XBT. Increasing age was associated with SIBO in females, but not in males.
Richard A Schatz, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States.
Richard A
RA
Schatz
Richard A Schatz, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States.
Qing
Q
Zhang
Richard A Schatz, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States.
Nilesh
N
Lodhia
Richard A Schatz, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States.
Jonathan
J
Shuster
Richard A Schatz, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States.
Phillip P
PP
Toskes
Richard A Schatz, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States.
Baharak
B
Moshiree
D000328:Adult; D000367:Age Factors; D000368:Aged; D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D015992:Body Mass Index; D001944:Breath Tests; D003430:Cross-Sectional Studies; D005260:Female; D005431:Florida / Q000453:epidemiology; D005767:Gastrointestinal Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000401:mortality; D006801:Humans; D007421:Intestine, Small / Q000382:microbiology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D014994:Xylose / Q000378:metabolism*
D015415:Biomarkers; D014994:Xylose
Bacteria; Breath tests; Gastroparesis; Intestine; Irritable bowel syndrome; Proton pump inhibitors; Small; Xylose