YOUNG VERSUS OLD GUT: DISTINCT AGE-RELATED CHARACTERISTICS IN IRRITABLE BOWEL SYNDROME

Objectives
Ageing seems to have a beneficial effect on irritable bowel syndrome (IBS) (Sperber et al. Gastroenterology 2021), and the odds of developing IBS are lower when age is above 50 years (Lovell & Ford CGH 2012). Older age may also affect symptom reporting and quality of life. In this study, we aimed to characterize IBS patients of different age, by comparing patient reported outcomes and measures of gut physiology.

Methods
IBS patients (n=1677; 74% females; Rome II–IV) that had completed questionnaires and gut physiology testing in studies of pathophysiologic mechanisms were included. Patient reported outcomes were gastrointestinal (GI) symptom severity (GSRS-IBS), psychological distress (HADS), somatic symptom severity (PHQ-12), GI-specific anxiety (VSI), and quality of life (IBS-QOL). Subsets of the patients underwent the following gut physiology tests: transit time by radiopaque markers and/or the wireless motility capsule, a rectal sensitivity test (barostat), anorectal manometry, and a lactulose/mannitol urinary excretion test for small bowel permeability.
Linear regression analyses (controlled for sex) were done to assess if age was associated with the dependent variables. IBS patients were stratified into age groups (‘younger’ 18–29 years; ‘intermediate’ 30–49 years; ‘older’ ≥50 years) and groups were compared by ANOVA.

Results
Most of the patient reported outcomes and measures of gut physiology were associated with age (Table 1). Younger patients had more severe GI symptoms compared to both patients of intermediate and older age, except for diarrhea (younger vs. intermediate) and constipation (younger vs. older). No differences in severity of GI symptoms were observed between patients of intermediate and older age. Younger age was associated with higher levels of general and GI-specific anxiety, and more severe somatic symptoms, and older age was associated with better QOL (Table 2). Older patients had longer oroanal transit times and colonic transit times compared to younger IBS patients, as well as a higher proportion with delayed transit time. Rectal urgency, discomfort, and pain thresholds were lower (=more sensitive) in patients of younger/intermediate age compared to older patients. Anorectal function differed between the groups with lower resting anal sphincter pressures in older patients compared to the other age groups. Small bowel permeability did not differ between the age groups (Table 2).

Conclusion
The overall symptom burden seems to decrease in IBS with increasing age, which may partly be related to age-related changes in GI sensorimotor function. Age is an important factor to take into consideration in the management of patients with IBS, as well as in pathophysiological research.