Validation of the Structured Assessment of Gastrointestinal Symptoms Scale to Support Standardized Evaluation and Follow-up.

OBJECTIVES: Patient reported outcome measures (PROMs) facilitate evaluation of patients and allow to better assess treatment effects. Validated tools are lacking for paediatric gastroenterological patients. We thus aimed to adapt and validate for paediatric populations a self-administered Structured Assessment of Gastrointestinal Symptoms (SAGIS) tool that previously has been validated in adult cohorts.

METHODS: Each item of the original SAGIS instrument was thoroughly reviewed for its relevance in the paediatric population. The resulting paediatric (p)SAGIS was utilized over a 35 months' period in consecutive patients in a paediatric outpatient GI-clinic. Principal components analysis (PCA) followed by Varimax rotation and confirmatory factor analysis (CFA) was performed in derivation and validation samples. Responsiveness to change was assessed in 32 children with inflammatory bowel disease (IBD) after 12 months of therapy.

RESULTS: The final paediatric SAGIS consisted of 21 GI-related Likert-type questions, 8 dichotomous questions assessing extra-intestinal symptoms and two most bothersome symptoms. 1153 children/adolescents completed a total of 2647 questionnaires. Cronbach's alpha was 0.89, indicating good internal consistency. PCA supported a five-factor model (symptom groups: abdominal pain, dyspepsia, diarrhoea, constipation, dysphagia/nausea), CFA showed good model fit (CFI:0.96, RMSEA:0.075). The initial mean total GI-symptom score in IBD-patients (8.7 ± 10.3) decreased to 3.6 ± 7.7 after 1 year of therapy (p<0.01), and four of five symptom group scores decreased significantly upon treatment (p<0.05).

CONCLUSIONS: The pSAGIS is a novel, easy to use, self-administered instrument for GI-symptom assessment in children/adolescents with excellent psychometric properties. It may standardize GI-symptom assessment and may enable uniform clinical analysis of treatment outcomes.