Open AccessDiscriminant and convergent validity of the GSRS‐IBS symptom severity measure for irritable bowel syndrome: A population study
Author(s) -
Ljótsson Brjánn,
Jones Michael,
Talley Nicholas J,
Kjellström Lars,
Agréus Lars,
Andreasson Anna
Publication year - 2020
Publication title -
ueg journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.667
H-Index - 35
eISSN - 2050-6414
pISSN - 2050-6406
DOI - 10.1177/2050640619900577
Subject(s) - irritable bowel syndrome , medicine , discriminant validity , constipation , quality of life (healthcare) , rating scale , convergent validity , population , confirmatory factor analysis , diarrhea , clinical psychology , psychometrics , structural equation modeling , psychology , developmental psychology , statistics , nursing , environmental health , mathematics , internal consistency
Background The Gastrointestinal Symptom Rating Scale–Irritable Bowel Syndrome (GSRS‐IBS) is a 13‐item measure of IBS symptom severity. The scale has been used in several studies, but its psychometric properties have been insufficiently investigated and population‐based data are not available. Objective The objective of this article is to establish the factor structure and discriminant and convergent validity of the GSRS‐IBS. Methods The study was based on a Swedish population sample (the Popcol study), of which 1158 randomly selected participants provided data on the GSRS‐IBS. We used confirmatory factor analysis (CFA) and compared total and subscales scores in different groups, including IBS diagnostic status, treatment‐seeking behavior, and predominant bowel habits. The GSRS‐IBS scores were also correlated with quality of life indexes. Results The sample included 164 participants with a confirmed Rome III IBS diagnosis and 994 participants without the disease. The CFA confirmed the subscales with one exception, in which the incomplete bowel‐emptying item belonged to the constipation subscale rather than the diarrhea subscale. The GSRS‐IBS total score and subscales were associated with diagnostic status, treatment‐seeking behavior, and quality of life dimensions. The relevant subscales scores also differed between the diarrhea‐ and constipation‐predominant subtypes of IBS. Conclusion The GSRS‐IBS total score and subscales have high discriminant and convergent validity. The CFA confirmed the overall validity of the subscales but suggest that a sense of incomplete emptying belongs to the constipation rather than the diarrhea symptom cluster. We conclude that the GSRS‐IBS is an excellent measure of IBS symptom severity in the general population.