# Stability of Classification Systems for Irritable Bowel Syndrome

## TL;DR

This study evaluates how stable different classification systems for irritable bowel syndrome are over 12 months, finding that stool form and psychological burden classifications are most stable.

## Contribution

The study introduces a comparison of four classification systems for IBS and identifies their stability over time.

## Key findings

- Stool form-based IBS classification showed the highest stability (κ = 0.60) over 12 months.
- Classification based on psychological burden also demonstrated moderate stability (κ = 0.54).
- Subgrouping by most troublesome symptom and latent class analysis showed lower stability (κ = 0.47 and κ = 0.37 respectively).

## Abstract

Irritable bowel syndrome (IBS) is a common disorder characterised by recurrent abdominal pain and altered bowel habits. Although IBS is classified according to stool form, symptom patterns fluctuate over time, posing challenges for subtype‐based management.

To assess stability of IBS classification over 12 months using four approaches: stool form, most troublesome symptom, a seven‐cluster latent class analysis (LCA) incorporating gastrointestinal and psychological symptoms and a simplified LCA based on degree of psychological burden.

Participants were recruited from ContactME‐IBS, a national UK registry. Individuals meeting Rome IV criteria for IBS completed validated online questionnaires at baseline and 12 months assessing gastrointestinal and psychological symptoms. Participants were sub grouped according to the four classification methods, and stability between baseline and follow‐up was evaluated using Cohen's kappa statistic.

Of 752 participants meeting Rome IV criteria at baseline, 352 completed 12‐month follow‐up, with 259 (73.6%) continuing to meet Rome IV criteria. The highest stability was observed for stool form‐based subtyping (κ = 0.60), particularly in IBS with diarrhoea (83% remained stable). Classification based on psychological burden showed similar stability (κ = 0.54). In contrast, subgrouping by most troublesome symptom (κ = 0.47) and the seven‐cluster LCA (κ = 0.37) demonstrated lower stability.

Different IBS classifications showed only moderate stability over 12 months, highlighting the fluctuating nature of the disorder. Stool form and psychological burden‐based systems were most stable, but no method fully captured IBS variability. Future work could develop dynamic models integrating gastrointestinal and psychological factors to better guide management.

Four classification systems for irritable bowel syndrome were evaluated over 12 months. Stool form and psychological burden‐classification approaches showed the greatest stability, whereas most troublesome symptom and latent class analyses were less stable, emphasising the fluctuating nature of IBS.