Prospective cohort study of phenotypic variation based on an anal sphincter function in adults with fecal incontinence

BackgroundOne-third of patients with fecal incontinence (FI) do not have any anal dysfunction. The aim was to characterize patients with FI with normal anal function compared with patients with anal weakness. MethodsThe general characteristics and data of anal manometry, endosonography, and defecography of patients who were evaluated for FI at a single institution from 2005 to 2015 were prospectively assessed. Fecal incontinence was defined by the Cleveland Clinic Incontinence Score (CCIS) >4. Anal weakness was defined by one or more of the three following parameters: <25 mmHg at the upper part of the anal canal, <26 mmHg at the lower part of the anal canal, and <60 mmHg for the mean squeeze pressure. Key ResultsA total of 439 patients with FI were included (152 with normal anal function/287 with anal weakness). Severe constipation (Kess score 21) was predominant in patients with normal anal function (44/151 vs 50/284, respectively; p = 0.0054). Fecal incontinence with normal anal function was significantly associated with lower age (>63 years; odds ratio [OR] = 0.29), higher weight (>65 kg; OR = 1.69), fecal urgency (OR = 1.58), less severe FI score (CCIS score >10; OR = 0.52), higher abdominal pressure (>36 mmHg; OR = 2.15), and paradoxical puborectal contraction (OR = 2.07) in a multivariate analysis model. Conclusion & inferencesFecal incontinence with normal anal function is a specific phenotype that involves distal constipation and may be an early stage of FI with anal weakness. Physicians should adapt their management to focus on the treatment of constipation.