Developing the Breast Utility Instrument, a preference-based instrument to measure health-related quality of life in women with breast cancer: Confirmatory factor analysis of the EORTC QLQ-C30 and BR45 to establish dimensions

Abstract

Objectives Breast cancer (BrC) and its treatments impair health-related quality of life (HRQoL). Utility is a measure of HRQoL that includes preferences for health outcomes, used in treatment decision-making. Generic preference-based instruments lack BrC-specific concerns, indicating the need for a BrC-specific preference-based instrument. Our objective was to determine dimensions of the European Organisation for Research and Treatment of Cancer (EORTC) general cancer (QLQ-C30) and breast module (BR45) instruments, the first step in our development of the novel Breast Utility Instrument (BUI). Methods Patients (n = 408) attending outpatient BrC clinics at an urban cancer centre, and representing a spectrum of BrC health states, completed the QLQ-C30 and BR45. We performed confirmatory factor analysis of the combined QLQ-C30 and BR45 using mean-and variance-adjusted unweighted least squares estimation. The hypothesized factor model was based on clinical relevance, item distributions, missing data, item-importance, and internal reliability of dimensions. Models were evaluated based on global and item fit, local areas of strain, and likelihood ratio tests of nested models. Results Our final model had 10 dimensions: physical and role functioning, emotional functioning, social functioning, body image, pain, fatigue, systemic therapy side effects, sexual functioning and enjoyment, arm and breast symptoms, and endocrine therapy symptoms. Good overall model fit was achieved: χ2/df: 1.45, Tucker-Lewis index: 0.946, comparative fit index: 0.951, standardized root-mean-square residual: 0.069, root-mean-square error of approximation: 0.033 (0.030–0.037). All items had salient factor loadings (λ>0.4, p<0.001). Conclusions We identified important BrC HRQoL dimensions to develop the BUI, a BrC-specific preference-based instrument.

Cross-cultural adaptation and psychometric properties of the Indonesian version for quality of life among breast cancer patients

“…It has 45 items, 23 of which are from the original QLQ-BR23, and has been translated into 19 languages (35). The English version of this questionnaire has been tested and found to be valid in Western countries (36,37); however, no specific validation and translation for Asian countries, including Indonesia, has been completed. To be able to translate the instrument into a good instrument in the target language, strategies should be applied to increase the accuracy of semantic equivalence with the target population, as well as to increase the conceptual accuracy where the concept of the source text is conveyed accurately and by taking the norms and culture of target population into account (38,39).…”

Developing the Breast Utility Instrument to Measure Health-Related Quality-of-Life Preferences in Patients with Breast Cancer: Selecting the Item for Each Dimension

“…This resulted in improved reliability (PSI = 0.784). SYS37 ( Hot flushes ), assigned to endocrine therapy from the confirmatory factor analysis, 25 was retained because it was rated most important by patients despite its high infit (1.81) and outfit (3.12) and uniform DIF (likelihood ratio χ 2 P = 0–0.419, McFadden’s pseudo R 2 = 0.001–0.023). Three items with low infit and outfit (<0.70) were retained ET63 ( Problems with your joints ), ET64 ( Stiffness in your joints ), ET65 ( Pain in your joints ) since iterative removal lowered model reliability (PSI < 0.7).…”

“…The sequence of applying the item importance approach could have influenced the final section of items. Patients and clinicians were asked to complete item importance ratings prior to our confirmatory factor analysis, 25 and the ranking of mean item importance ratings were considered in our final selection of each item per dimension.…”

“…In this study, we describe selecting 1 item representing each dimension using the same sample of our previous confirmatory factor analysis of the QLQ-C30 and BR45. 25 …”

Improving the Hearing Status Discrimination of the Health Utilities Index, Mark 3: Design of the Hearing Status Classification System

“…Item importance surveys like the one employed in this study have been demonstrated to be a reliable means of item selection for this purpose (7,8). The use of factor analysis and IRT in the generation of condition-specific utility instruments is a subject of ongoing research (20).…”