Inter- and intra-observer reliability of BITSS scale in the diagnosis and early follow-up of infectious diarrhea in children under 3 years of age

Abstract

The BITSS scale (Brussels Infant and Toddler Stool Scale) is an instrument used in the diagnosis and follow-up of infants and young children with infectious diarrhea. It consists of 7 pictures of diapers with different types of stools. 

Objective: To determine intra and interobserver reliability of the BITSS scale in infants and children using diapers. 

Patients and Method: Reliability study. Three pediatricians with experience in treating childhood infectious diarrhea were selected and, after training in applying the BITSS scale, they evaluated 70 pictures of stools obtained from pediatric patients, representing the 7 different types of stools categorized by the scale (10 images for each item). Two pediatricians participated in the interobserver reliability study and performed a blind evaluation of the same pictures, assigning a value to each one, and the third pediatrician participated in the intra-observer analysis, evaluating 70 images on two different occasions, 15 days apart. Interobserver agreement and kappa statistics were determined for the scale and each scale item. 

Results: 280 measurements were made, 140 for the inter-observer reliability study and 140 for the intra-observer one. The degree of inter-observer agreement for the scale was 85.7%; with a kappa of 0.817 (95% CI 0.72; 0.92), and standard error of 0.05; and the intra-observer kappa for the scale was 0.883 (95% CI 0.80; 0.96), with a standard error of 0.04. 

Conclusions: The BITSS scale has good intra- and interobserver reliability.