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Research Project: Pediatric Clinical Nutrition

Location: Children's Nutrition Research Center

Title: Bristol Stool Form Scale reliability and agreement decreases when determining Rome III stool form designations

item CHUMPOITAZI, B - Baylor College Of Medicine
item SELF, M - Texas Children'S Hospital
item CZYZEWSKI, D - Baylor College Of Medicine
item CEJKA, S - Texas Children'S Hospital
item SWANK, P - University Of Texas Health Science Center
item SHULMAN, R - Children'S Nutrition Research Center (CNRC)

Submitted to: Neurogastroenterology & Motility
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2015
Publication Date: 3/1/2016
Citation: Chumpoitazi, B.P., Self, M.M., Czyzewski, D.I., Cejka, S., Swank, P.R., Shulman, R.J. 2016. Bristol Stool Form Scale reliability and agreement decreases when determining Rome III stool form designations. Neurogastroenterology & Motility. 28(3):443-448.

Interpretive Summary: The Bristol Stool Form Scale (BSFS) is an important tool used by healthcare workers and researchers to allow patients to describe their stools and the response of stools to changes in diet or medications. It also is used to determine if a patient's stools are normal. We had gastroenterologists use the BSFS to determine if they agreed on how to describe stools based on the BSFS. We found that the gastroenterologists could accurately describe stools with the BSFS but could not agree on whether stools were normal or not. Further studies are needed to define normal stooling patterns and develop better methods to describe normal stools.

Technical Abstract: Rater reproducibility of the Bristol Stool Form Scale (BSFS), which categorizes stools into one of seven types, is unknown. We sought to determine reliability and agreement by individual stool type and when responses are categorized by Rome III clinical designation as normal or abnormal (constipation or diarrhea).Thirty four gastroenterology providers from three institutions rated 35 stool photographs using the BSFS. Twenty rerated the photographs. 1190 individual stool type ratings were completed. Though only four photographs had absolute agreement (all Type 1 or Type 7), general agreement was high with 1132 (95.1%) of ratings being within one category type of the modal rating. Inter-rater and intra-rater reliability of the BSFS by individual stool type wasexcellent with intraclass correlations of 0.88 (95% CI: 0.86–0.90, p < 0.001) and 0.89 (95% CI: 0.86–0.91, p < 0.001), respectively. However, agreement decreased when using Rome III designations with 13 (37%) photographs having significantly diverging classifications (semi-interquartile range = 0.5). These 13 photographs were rated by the majority of raters as either type 2 vs type 3 or type 5 vs type 6 stools, representing the boundaries of normal vs abnormal stools. Inter-rater and intra-rater reliability of the BSFS by Rome III clinical categorization decreased with intraclass correlations of 0.75 (95% CI: 0.69–0.81,p < 0.001) and 0.65 (95% CI: 0.49–0.81, p < 0.001), respectively. We conclude that the Bristol Stool Form Scale has excellent reliability and agreement when used to rate individual stool type by raters. However, BSFS reliability and agreement decreases when determining Rome III stool form categories.