Do Age and Sex Influence Anorectal Manometry Parameters?

High-resolution anorectal manometry (HRM) is widely used in the evaluation of anal incontinence and constipation, which become increasingly prevalent with age. However, the impact of age and comorbidities on physiological digestive parameters remains poorly understood. In this study, we aimed to evaluate the effect of age on anorectal function.

We conducted a retrospective study on patients at our digestive motility clinic between January 2016 and May 2019. All patients with a normal HRM were included. Clinical data and HRM parameters were collected in a database. Multivariate regression analyses were performed to evaluate the effects of age, sex, medical comorbidities and obstetric history on anorectal HRM parameters.

One hundred and forty-four patients were included (mean age: 53 ± 16 years, 72% females). The main indications for anorectal HRM were incontinence (44%), constipation (37%) and anorectal pain (9%). Age was significantly associated with higher maximum tolerable volume (β = +0.48 mL year^-1, P = 0.04) and higher rectal compliance (β = +0.04 mL year^-1, P = 0.01). Independently from age and medical comorbidities, female demonstrated significantly lower mean endurance squeeze pressure (β = -44.4 mmHg, P < 0.001), maximal squeeze pressure (β = -62.3 mmHg; P < 0.001), volume at first urge (β = -16.7 mL, P = 0.02) and maximum tolerable volume (β = -16.1 mL, P = 0.046). Vaginal birth was associated with lower tolerable maximum pressure (β = -39.4 mmHg, P = 0.046).

Age and sex are independent factors which influence anorectal HRM parameters. These findings should be taken into consideration when interpreting anorectal HRM.