RESUMEN
OBJECTIVES: The Brussels Infants and Toddlers Stool Scale (BITSS) was developed for the assessment of stool consistency in non-toilet-trained children. This study aimed to (1) investigate the intra-rater reliability of the BITSS among health care professionals (HCPs) and caregivers (CGs); (2) study a potential learning curve; (3) explore the impact of photo quality on intra-rater reliability. METHODS: Photos of diapers containing stool were assessed twice by 4 HCP (2432 photos) and 8 CGs (492 photos) using the BITTS. Intra-rater reliability was calculated by the percentage of exact agreement and a κ-value. A learning effect and the impact of photo quality was explored using mixed linear model and generalized estimating equations. RESULTS: HCPs generated 24,320 stool consistency ratings: 12.1% were scored as watery, 31.0% loose, 29.4% formed, and 27.6% hard. CGs performed 7872 ratings: 9.2% classified as watery, 34.6% loose, 28.9% formed, and 27.3% hard. Intra-rater reliability (κ) for HCPs ranged from 0.64 [95% confidence interval (CI) = 0.61-0.66] to 0.78 (95% CI = 0.76-0.80) and from 0.68 (95% CI = 0.63-0.73) to 0.94 (95% CI = 0.91-0.97) in the CG group. Both groups had <1% improvement in the odds of identical classification per 50 photos. The percentage of absolute agreement was higher in photos rated as good quality than those that were not (HCPs: 80.3% vs 69.5%, P < 0.001; CGs: 90.4% vs 86.3%, P < 0.001). CONCLUSIONS: The BITSS has an excellent intra-rater reliability for the stool consistency scoring of photographs of stools in diapers, but can be influenced by photo quality. A clinically meaningless learning effect was found.
