Table 1.
Patient demographics and characteristics
| Parameter | Rifaximin 1200 mg/day (n = 162) | Rifaximin 2400 mg/day (n = 81) |
|---|---|---|
| Mean age (range), years | 58 (17–91) | 60 (17–91) |
| Male:Female | 37:125 | 22:59 |
| Race, n (%) | 43 (27) | 25 (31) |
| White | 2 (1) | 1 (1) |
| Black | 2 (1) | 0 (0) |
| Asian | 4 (2) | 2 (2) |
| Hispanic | 2 (1) | 2 (2) |
| Other | 109 (67) | 51 (63) |
| Not reported | 43 (27) | 25 (31) |
| Mean duration of IBS (range), mo | 113.1 (6–480) | 128.4 (6–480) |
| Disease subclass, n (%) | ||
| IBS-D | 45 (28) | 24 (30) |
| IBS-C | 33 (20) | 16 (20) |
| IBS-M | 24 (15) | 11 (14) |
| Not reported | 60 (37) | 30 (37) |
| Lactulose breath test results, n (%)a | ||
| Distal positiveb | 17 (10) | 10 (12) |
| Hydrogen | 91 (56) | 44 (54) |
| Methane | 32 (20) | 18 (22) |
| Hydrogen and methane | 9 (6) | 4 (5) |
| High baselinec | 23 (14) | 10 (12) |
| Flatlined | 27 (17) | 15 (19) |
| Negativee | 4 (2) | 1 (1) |
| Inconclusive | 34 (21) | 18 (22) |
Notes:
a
Patients positive for hydrogen, methane, or both gases may have exhibited a high baseline or lacked a biphasic excretion pattern (distal positive);
b
patients who did not exhibit a biphasic pattern of gas excretion;
c
patients with ≥20 ppm before lactulose ingestion;
d
patients with a < 10 ppm increase in gas excretion within 120 minutes of lactulose ingestion;
e
patients with a < 10 ppm increase in gas excretion within 90 minutes of lactulose ingestion.
Abbreviations: IBS, irritable bowel syndrome; IBS-D, diarrhea-predominant irritable bowel syndrome; IBS-C, constipation-predominant irritable bowel syndrome; IBS-M, mixed-symptom irritable bowel syndrome.