Comparison of the Bristol Stool Scale and modified version for children: Use by providers vs children: BSFS vs mBSFS-C.

Introduction: Accurate report of stool form is essential to diagnosis and assessment of treatment response. The modified Bristol Stool Form Scale for Children ( mBSFS-C ) classifies stool form into 5 types and is reliable and valid. However, a direct comparison of provider's and children's ratings using the mBSFS-C vs the traditional Bristol Stool Form Scale ( BSFS ) that uses 7 stool form types has not been done.

Methods: Pediatric gastroenterology providers and children rated the same 35 stool photos, reflecting diverse stool forms, using both scales. The order of photo presentation and scale use were randomized. For each photo, the most common rating (modal rating) was calculated for both scales and study samples. The percentage of child and provider ratings matching their respective modal ratings was determined.

Results: Twenty-one providers (21 faculty, 11 fellows, 3 nurse practitioners) and 200 children (mean age 12 ± 3 years) participated. No order effect (mBSFS-C vs BSFS used first) was observed. Of 1225 provider ratings using the mBSFS-C, 90.0% agreed with the provider's modal ratings vs 77.8% using the BSFS. Of 7,000 child ratings using the mBSFS-C, 84.6% agreed with the children's modal ratings vs 71.8% using the BSFS. Using providers' modal ratings as the reference, all mBSFS-C photograph modal ratings matched between children and providers (35/35 photos) whereas only 86% (30/35 photos) matched with the BSFS.

Conclusions: 1) The mBSFS-C showed greater modal agreement among both providers and children compared to the BSFS; 2) Provider-child concordance was greater with the mBSFS-C than with the BSFS. Validation in other regions/populations is needed.