Unveiling the applicability of the Brussels Infant and Toddler Stool Scale for hard stool in young children: A South Asian perspective

Background and Aim: The Rome IV criteria, the standard for diagnosing functional constipation (FC), deem the Bristol Stool Scale (BSS) unsuitable for assessing stool consistency in young children. Hence, the Brussels Infant and Toddler Stool Scale (BITSS) was developed. We aimed to validate and test the reliability of BITSS for hard stools and FC among infants and toddlers, where there is limited evidence in Asian populations. Methods: The research evaluated FC in children aged 0–48 months who came for medical examination using Rome IV criteria. Stool properties provided by caregivers were assessed sequentially through three methods: the BSS, the BITSS, and caregiver reports. Results: A total of 370 responses were received, with an average age of 26.2 months. Substantial agreement was observed between the BITSS and caregiver reports for hard stools (concordance rate: 91.9%, κ = 0.75), while near-perfect agreement was found between BITSS and BSS (concordance rate: 93.5%, κ = 0.81). The BITSS exhibited higher sensitivity than the BSS in assessing hard stools (95.3% vs 87.5%, P < 0.001). And the BITSS (23.5%) identified the highest prevalence of FC than the BSS (20.5%) and caregiver report (18.7%), with near-perfect agreement. Moderate agreement was reported when evaluating the test–retest reliability between BITSS and caregiver reports (concordance rate: 86.2%, κ = 0.44). Conclusions: The BITSS, more sensitive than the BSS in identifying abnormal, especially hard stools, aids in early FC detection in young children. These findings support using BITSS over BSS for evaluating hard stools in infants and toddlers, both in Vietnam and globally.