Lactulose Breath Testing Does Not Discriminate Patients With Irritable Bowel Syndrome From Healthy Controls

Jason R. Bratten, B.S.; Jennifer Spanier, D.O.; Michael P. Jones, M.D.

Disclosures

Am J Gastroenterol. 2008;103(4):958-963. 

In This Article

Results

Two hundred seventy-nine patients were referred during the study period for LBT with a presumptive diagnosis of IBS, and two hundred twenty-four patients met Rome II criteria for IBS and did not have exclusion criteria (80%). Forty controls were also studied. All patients with IBS were referred by gastroenterologists practicing at Northwestern Memorial Hospital, with 58% of cases referred by the university practice group and 42% by private practice gastroenterologists. The control group was approximately 10 yr younger than the IBS group (33 ± 11 yr vs 43 ± 14 yr, t = 3.78, P = 0.002), but did not differ significantly with respect to gender (controls 9 M/31 F, IBS 41 M/183 F, χ2 = 0.45, P = 0.51). There was no correlation between age and either baseline breath H2 concentration or orocecal transit times for either controls or patients with IBS. For controls and patients with IBS, the correlations of age with baseline breath H2 levels were -0.09 (P = 0.62) and -0.07 (P = 0.38), respectively. For controls and patients with IBS, the correlations of orocecal transit time with age were -0.25 (P = 0.28) and -0.11 (P = 0.15), respectively.

CH4 production was found in 20% (44 of 224) of patients with IBS and 15% (6 of 40) of controls (χ2 = 0.48, P = 0.49). Among CH4-producing subjects, six out of six controls and 41 out of 44 patients with IBS also had detectable levels of breath H2 at baseline. Baseline breath H2 levels were significantly lower in CH4-producing patients with IBS than in non-CH4-producing patients with IBS (2.27 ± 2.07 vs 5.32 ± 6.02, P = 0.001). The difference was not significant for controls, although the number of CH4-producing controls was so small as to limit the value of statistical comparison. CH4-producing patients with IBS were significantly more likely than non-CH4-producing patients to report constipation (odds ratio [OR] 2.22, 95% CI 1.14-4.33, P = 0.02), and significantly less likely to report diarrhea as a major symptom (OR 0.33, 95% CI 0.16-0.67, P = 0.001) ( Table 1 ). No statistically significant association existed between CH4 production and symptoms of bloating or pain.

After excluding CH4-producing subjects, no significant differences existed between patients with IBS and controls for previously reported criteria for abnormal studies ( Table 2 ). Overall, 74% of patients with IBS had abnormal patterns of breath H2 excretion defined as either a rise in breath H2 that occurred less than 90 min after lactulose ingestion or an increase in breath H2 concentration of more than 20 ppm. Twenty-seven percent of subjects were positive by either criterion, and 46% were positive by both criteria. For controls, 85% were positive using the same criteria, with 35% positive for either criterion and 50% positive for both criteria. Dual H2 peaks were seen in 14% of patients with IBS and 26% of controls. Controls and patients with IBS did not differ significantly with respect to the percentage of subjects meeting any of the previously reported criteria for an abnormal LBT, although controls tended to be more likely than patients with IBS to manifest dual H2 peaks.

Controls and patients with IBS also demonstrated similar breath H2 excretion patterns over time (Fig. 1). Comparisons between breath H2 concentrations at each time point were made using unpaired t-tests. No statistically significant differences existed at any time point. Mean orocecal transit times did not differ significantly between controls (87 ± 56 min) and patients with IBS (96 ± 53 min, t = 0.969, P = 0.33).

Comparison of the rise in breath H2 over time in patients with IBS (solid line) and controls (dashed line). No significant differences are seen over time between the two groups.

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