Efficacy of washed microbiota transplantation for therapeutic targets of refractory functional constipation and the influencing factors: a single-center, retrospective, 24-week follow-up study

BACKGROUND: The efficacy of washed microbiota transplantation (WMT) in terms of refractory functional constipation (FC)-related therapeutic targets and influencing factors have not been elucidated. This study aimed to assess the efficacy and influencing factors of WMT in treating refractory FC-related therapeutic targets. METHODS: The clinical data of patients diagnosed with refractory FC and received with WMT were retrospectively collected. The therapeutic targets included straining, hard stools, incomplete evacuation, a sense of anorectal obstruction, manual maneuvers, and decreased stool frequency. Each target was recorded as 1 (yes) or 0 (no). All patients were followed up for approximately 24 weeks from the end of the first course of WMT. The primary outcomes were the improvement rates for the individual therapeutic targets and the overall response in respect of the therapeutic targets decreased by 2 at weeks 4, 8, and 24. The secondary outcomes were the clinical remission rate (i.e., the proportion of patients with an average of 3 or more spontaneous complete bowel movements per week), clinical improvement rate (i.e., the proportion of patients with an average increase of 1 or more SCBMs/week or patients with remission), stool frequency, Wexner constipation score, Bristol Stool Form Scale (BSFS) score, and adverse events. The factors influencing the efficacy were also analyzed. RESULTS: Overall, 63 patients with 112 WMT courses were enrolled. The improvement rates at weeks 8 and 24 were 45.6% and 35.0%, 42.9% and 38.6%, 45.0% and 35.7%, 55.6% and 44.4%, and 60.9% and 50.0%, respectively, for straining, hard stools, incomplete evacuation, a sense of anorectal obstruction, and decreased stool frequency. The overall response rates were 49.2%, 50.8%, and 42.9%, respectively, at weeks 4, 8, and 24. The rates of clinical remission and clinical improvement were 54.0% and 68.3%, respectively, at weeks 4. The stool frequency, BSFS score, and Wexner constipation score tended to improve post-WMT. Only 22 mild adverse events were observed during the 112 WMT courses and the follow-up. The number of WMT courses was identified to be the independent factor influencing the efficacy. CONCLUSIONS: WMT is efficacious in improving refractory FC-related therapeutic targets. The effectiveness of WMT in the management of FC is enhanced with the administration of multiple courses.