P147 The valuation of the Short Inflammatory Bowel Disease Questionnaire for use in economic evaluations
P. Petryszyn*1, P. Piotrowski2, P. Ekk-Cierniakowski3, A. Staniak1, M. Well4
1Wroclaw Medical University, Clinical Pharmacology, Wroclaw, Poland, 2Wroclaw Medical University, Wroclaw, Poland, 3Warsaw School of Economics, Warsaw, Poland, 4Wroclaw University of Economics, Wroclaw, Poland
The employment of general instruments (such as EQ-5D) validated using direct preferences measurement techniques in inflammatory bowel disease (IBD) patients is limited. The Short Inflammatory Bowel Disease Questionnaire (SIBDQ) is a health-related quality of life (HRQoL) tool evaluating physical, social, and emotional status. The aim of this study was to value health states defined by the SIBDQ using the time trade-off (TTO) technique so that outcome can be used directly to estimate quality adjusted life years (QALYs).
Health states defined by the SIBDQ were valued by pharmacy students (n = 135, 113F, 22 M, 22–29 years, mean 24 ± 1.4 years) and IBD patients (n = 169, 93 F, 76 M, 18–61 years, mean 29.9 ± 8.98 years, 84 Crohn’s disease [CD], 73 ulcerative colitis [UC], 12 IBD undetermined). Before the valuation task, the respondents gained experience with TTO using general health states as defined by the EQ-5D questionnaire. Then they had to imagine that they were in a SIBDQ defined chronic health state. TTO values ranged from 1.0 for perfect health to 0.0 for the value of death. As the SIBDQ provides 710 = 282 475 249 unique health states, to facilitate the administration of TTO we firstly reduced the number of health states using factor analysis and merging of answer levels. As a result, we obtained 34 = 81 health states (4 factors corresponding to 4 dimensions of SIBDQ [systemic, social, emotional, and bowel], together with 3 response categories [usually, half the time/sometimes, and rarely/never]).
We obtained 405 useable valuations by pharmacy students and 507 by IBD patients. The worst health state was valued at 0.6 and 0.5 by students and patients, respectively. The significant predictors of utility weights in a multivariable regression analysis were SIBDQ total score (β = 0.046), systemic (β = 0.021), social (β = 0.031), emotional (β = 0.022), and bowel (β = 0.045) dimensions according to students and SIBDQ total score (β = 0.04), social (β = 0.031), and emotional (β = 0.044) dimensions according to patients.
The valuation of the SIBDQ facilitates economic evaluation of new pharmaceutical interventions for IBD. The differences observed between the results of the valuation carried out in healthy people and IBD patients point out the phenomenon of compensation and relative importance of social and emotional issues from the patient perspective.