Development and Validation of a Short Bowel Syndrome (SBS) Specific Quality of Life Scale

Rationale: GLP-2 analogues are developed for treatment of SBS. To measure treatment-induced health-related quality of life (HRQoL) changes over time, a patient-reported SBS-specific QoL scale (SBS-QoL™) was developed and validated. Methods: Principles from classical test theory and FDA guidance on patient-reported outcome measurements were applied. Item generation was based on literature, input from experts, physicians, and SBS patients. After item aggregation and raw scale construction, SBS-QoL™ was assessed in international focus groups. A factor analysis was done based on data from a multinational non-interventional observation in 185 SBS patients; construct validity (correlation to HPN-QoL© ) and internal consistency were evaluated. Test re-test reliability and responsiveness were determined in scope of a randomized, double-blind, placebo-controlled, multinational study in 86 SBS patients. Results: The self-administered SBS-QoL™ comprises 17 items measured by visual analogue scales and illustrated by pictograms. SBS patients assessed the scale as easy to handle and comprehensive. Factor analysis resulted in 2 subscales consisting of 11 and 6 items; no item was excluded. Construct validity was shown by a correlation coefficient of 0.74. SBS-QoL™ exhibits high internal consistency (Cronbach’s a: 0.95) and a measurement error of 5.4%. High test re-test reliability (correlation coefficient: 0.95) and responsiveness (responsiveness index: >0.8) of the scale were proven. Conclusion: SBS-QoL™ is a validated scale to measure treatment-induced HRQoL changes over time in SBS patients. Its psychometric properties are excellent.