Is factor analysis as credible as other statistical tests of association and difference for assessing the construct validity of quality of life measures?

Construct validation of quality of life (QoL) instruments examines the degree to which they measure what they are supposed to measure. Though most validation exercises are based on statistical tests of difference/association, confirmatory factor analysis (CFA) has also been proposed as an alternative validation method. However, little is known about whether validation using CFA alone is sufficient and/or whether CFA validation results are comparable to those of other statistical tests. This issue is addressed within the context of validating six QoL instruments: the Women’s Health Questionnaire (WHQ-23), Fertility quality of life tool, (FertiQoL) the Adult Social Care Outcomes Toolkit (ASCOT), EuroQoL 5-Dimensions 5-Level (EQ5D-5L) and the Short-Form 6 Dimensions (SF6D).