The WHOQOL-BREF: a modern psychometric evaluation of its internal construct validity in people with multiple sclerosis

Abstract

Purpose Symptoms of Multiple Sclerosis (MS) differentially impact upon quality of life (QoL) and a comprehensive measure is required for use in observational and interventional studies. This study examines the abbreviated World Health Organisation Quality of Life tool (WHOQOL-BREF) which was designed to be used as a broad measure of QoL across different cultures and diseases. Methods Data were collected from 3186 subjects as part of the TONiC study in MS and was examined with a systematic, iterative approach using Rasch analysis to investigate the internal construct validity of the WHOQOL-BREF. Results Mean age was 49.8 years (SD 11.8), disease duration was 11.2 years (SD 9.6) and 73.2% were female. Subjects represented all stages of MS with EDSS scores of 0-4, 4.5-6.5, 7-7.5 and ≥ 8 seen in 49.8%, 38.5%, 6.8% and 4.9% of patients, respectively. Using a super-item approach, it was possible to demonstrate fit to the assumptions of the Rasch model for 3 of the 4 domains of the WHOQOL-BREF (physical, psychological and environment) as well as a broad 24-item total score. In addition, item subsets derived from the stem of each question were shown to function as novel scales measuring impact and life satisfaction. We have provided transformation tables from ordinal raw scores to interval scales where data are complete. Conclusions The validation of multiple conceptual frameworks validates the WHOQOL-BREF as a powerful and flexible end-point for use in clinical trials and in testing conceptual models of factors influencing QoL in MS.

An item analysis according to the Rasch model of the German 12-item WHO Disability Assessment Schedule (WHODAS 2.0)

“…The proportion of explained common variance (ECV) [31][32][33] of the general factor should be > 0.9 to consider the scale as unidimensional. The ECV is indicated in RUMM2030 as A-factor [31]. One more assumption is that there is no item bias with regard to exogenous variables (no DIF).…”

German Translation, Cultural Adaption and Validation of the Unidimensional Self-efficacy Scale for Multiple Sclerosis Using Rasch Analysis

“…Residual correlations of + 0.2 above the mean correlation of the total matrix indicate local dependence (27). This denotes a confounding factor inducing an association between items, or multidimensionality (28,29). In the presence of item-dependency, two "super-items" can be created from alternative items and compared with each other running a robust conditional chi-square test of t (28).…”

“…This denotes a confounding factor inducing an association between items, or multidimensionality (28,29). In the presence of item-dependency, two "super-items" can be created from alternative items and compared with each other running a robust conditional chi-square test of t (28). The proportion of common to total variance retained in a bi-factor equivalent solution corresponds to the explained common variance (ECV) (30).…”

“…The proportion of common to total variance retained in a bi-factor equivalent solution corresponds to the explained common variance (ECV) (30). For a unidimensional scale, the ECV should be > 0.9, indicating that > 90% of the variance is common and retained in the latent estimate (28). which was based upon the unrestricted or partial credit model (34).…”

Evaluation of the quality of life of patients submitted to renal replacement therapy: cross-sectional study

“…Therefore, the importance of measuring it to assist professionals in the construction of care plans according to the needs of these patients (Luxardo et al, 2017). To assess QoL, some instruments were constructed such as Whoqol-Bref, with 26 questions, which evaluates the social, physical, psychological domains among others and whose score ranges from 0 to 100 points.Another questionnaire used is the SF-36 which can assess QoL in a generalized way, with ease of understanding and application, containing 11 questions, with scores ranging from 3 to 10 points each, with 9 domains, of which 8 will be classified individually and the overall condition in general (Pomeroy et al, 2020). Therefore, nursing plays a relevant role in assisting these patients seeking quality of life.…”