Probiotic therapy of the irritable bowel syndrome (IBS)

Probiotic therapy trials in IBS have produced conflicting results. It is unknown whether therapeutic efficacy can be optimized when the study is conducted in collaboration with primary care physicians.

Methods: Two hundred ninety-seven patients (117: 180 males: females, 49.8±14.4 years of age) with lower abdominal symptoms (abdominal pain, diarrhea, constipation) diagnosed as IBS according to the WONCA criteria of World Health Organization (WHO) primary care physicians (1983, 1998) were recruited in 10 primary care centers, and were treated for 8 weeks by the probiotic compound Pro-Symbioflor (R) (Symbiopharm GmbH, Herborn, Germany), (3×1.5ml daily), an E-coli prepapration containing 6 to 10 different bacterial clones, or placebo in a double-blinded, randomized fashion. Patients were seen weekly by the physician, who assessed the presence or absence of a total of 9 gastrointestinal and related symptoms. Responders were defined as having at least a 50% decrease in overall symptom score as well as in abdominal pain reports, to match current standards in IBS trial response definitions as set by FDA and EMEA. Response rates were compared between groups by means of chi-square test or Fisher's exakt test; in addition, the time course of responses was compared by means of Kaplan-Meier analysis.

Results: The overall symptom response to the drug was 68.5% in comparison to placebo with 37.8%, the difference was statistically significant (p<0.001). The relative benefit of the compound in comparison to placebo was 1.8, i.e. nearly double the number of patients profited from verum than from placebo, and resulted in a low number-needed-to treat (NNT) of 3.3. The result was similar for the abdominal pain report (benefit: 1.7, NNT: 3.5). While superiority of one center was noted (benefit: 1.2; NNT: 8.3), all other centers also had significant results (benefit: 1.7; NNT: 8.1). No significant differences were found between men and women. Kaplan-Meier analysis revealed a mean response time of 5.4 weeks for verum and 6.9 weeks for placebo (Kaplan estimator, p<.0001).

Conclusion: Probiotic treatment of IBS is effective, and superior to other treatment options because of low NNT.

(Supported by a research grant from Symbiopharm)