Irritable bowel syndrome symptom severity improves equally with probiotic and placebo

Figure 1 Study outline. Volunteers were selected for screening visits by a prescreen for compliance over the phone. Eligible volunteers entered an 8-wk run-in period without any investigational product (IP) consumption and were thereafter randomized to receive low- or high-dose active IP or a placebo IP for 12 wk. The intervention period was followed by a 4-wk washout period without any IP consumption. Preceding each time point (weeks 0, 4, 12, and 16), volunteers recorded their stool consistency during each defecation event for 7 d. At each time point, questionnaires [Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS); IBS-related Quality of Life (IBS-QoL); Hospital Anxiety and Depression Score (HADS)] were filled out. All volunteers were contacted by phone prior to each sampling time point to inquire about adverse events (AEs) and to remind of the sampling procedures.

Figure 2 Disposition of volunteers. During the 8-wk run-in period prior to randomization, 17% of eligible volunteers dropped out. After randomization, most volunteers (87%) completed the trial. Withdrawals were evenly distributed between treatment groups. Low- and high-dose treatment groups received 10⁹ or 10¹⁰ CFU Lactobacillus acidophilus NCFM daily.

Figure 3 Irritable bowel syndrome symptom severity score over time. IBS-SSS is a 5-item composite score inquiring about the severity of abdominal pain, bloating/distension, satisfaction with bowel habits, and IBS-related quality of life on a 10-cm VAS scale and the number of days with abdominal pain over the past 10 d[18]. All items are scored from 0 to 100, allowing for IBS-SSSs to range from 0 to 500. Francis and colleagues have validated non-IBS controls and volunteers suffering from mild, moderate, and severe IBS symptoms to range between 0-75, 75-175, 175-300, and 300-500, respectively[18]. The composite symptom score declined similarly in all treatment groups during the intervention, showing no treatment effect for the active groups (low-dose and high-dose) receiving Lactobacillus acidophilus NCFM. The severity scores are given as mean ± SD. Differences from baseline to week 12 were not significant between treatment groups. All within-group comparisons to baseline (week 4, week 12, and washout) were significant (P < 0.001). IBS-SSS: Irritable bowel syndrome symptom severity score; IBS: Irritable bowel syndrome.