METHODS: In this double-blind, randomized, placebo-controlled, single-center trial, 280 patients with PD were screened, and 72 eligible patients were block-randomized (1:1) to receive either multistrain probiotics capsules (n = 34) or identical-appearing placebo (n = 38), for 4 weeks. The primary endpoint was the change in the average number of spontaneous bowel movements (SBM) per week during the last 2 weeks of intervention compared with the 2-week preintervention phase, recorded by daily stool diary. Secondary outcome measures included changes in stool consistency, constipation severity score, and quality of life related to constipation. Satisfaction with intervention received was assessed. Change in levels of fecal calprotectin, a marker of intestinal inflammation, was an exploratory outcome.

RESULTS: SBM increased by 1.0 ± 1.2 per week after treatment with probiotics and decreased by 0.3 ± 1.0 per week in the placebo group (mean difference 1.3, 95% confidence interval 0.8-1.8, p < 0.001). Significant improvements were also seen for secondary outcomes after correction for multiple comparisons, including stool consistency (p = 0.009) and quality of life related to constipation (p = 0.001). In the treatment group, 65.6% reported satisfaction with the intervention vs only 21.6% in the placebo group (p < 0.001). One patient (2.9%) in the treatment group withdrew due to a nonserious adverse event. Fecal calprotectin did not change significantly during the study.

CONCLUSIONS: Multistrain probiotics treatment was effective for constipation in PD. Further studies are needed to investigate the long-term efficacy and safety of probiotics in PD, as well as their mechanisms of action.

CLINICALTRIALSGOV IDENTIFIER: NCT03377322.