Reliability and Validity of a Modified Bristol Stool Form Scale for Children

Abstract

Objectives This study sought to: 1) evaluate the ability of children to reliably use a modified Bristol Stool Form Scale for Children (mBSFS-C), 2) evaluate criterion-related validity of the mBSFS-C, and 3) identify the lower age limit for mBSFS-C use. Study design The mBSFS-C comprises five stool form types described and depicted in drawings. Children 3–18 years rated stool form for ten stool photographs. Due to low reliability when stool form descriptors were not read aloud (n=119), a subsequent sample (n=191) rated photographs with descriptors read. Results Intraclass correlation coefficients for descriptor-unread versus -read samples were 0.62 and 0.79. Children were increasingly reliable with age. Percentage of correct ratings varied by stool form type but generally increased with age. With descriptors unread, children 8 years and older demonstrated acceptable inter-observer reliability with over 78% of ratings correct. With descriptors read, children 6 years and older demonstrated acceptable reliability and over 80% of ratings correct. Conclusions The mBSFS-C is reliable and valid for use by children, age 6 being the lower limit for scale use with descriptors read and age 8 without descriptors read. We anticipate that the mBSFS-C can be effectively used in pediatric clinical and research settings.