The abilitator summary scale items and summary scores

Objectives According to the Consensus-based Standards for the selection of
health Measurement Instruments (COSMIN) panel, structural validity
describes how well Patient-Reported Outcome Measures’ (PROM) scores
reflect the dimensions of the measured construct. Reaching structural
validity is important for PROMs that reflect unidimensional effect
indicators, but not for formative PROMs in which the items are not
necessarily correlated. The main purpose of this study was to examine the
structural components of the Abilitator, a co-developed self-report
questionnaire on work ability and functioning for the population in a weak
labour market position. Methods We examined to what extent the Abilitator
has reflective and formative elements in its five summary scales: “C.
Inclusion”, “D. Mind”, “E. Everyday life”, “F. Skills”, and “G. Body”. The
Abilitator data sample (n=4555, men 51%, mean age 37 years) was collected
in 2017–2022 by the Finnish Institute of Occupational Health in
cooperation with the European Social Fund Priority 5 projects in which the
participants have multiple challenges to gain employment. For the
structural components and validity analysis we implemented both
Confirmatory Factor Analysis (CFA) and Exploratory Factor Analysis (EFA).
Results Based on the COSMIN criteria for structural validity, the
Abilitator reached approximate model fit with CFA when we analysed the
different concepts of the questionnaire separately rather than in one
unified model. An exception was “E. Everyday life” which was a formative
summary scale, and it did not reach approximate fit. EFA showed that the
items in the Abilitator’s summary scales loaded on ten factors.
Conclusions The Abilitator had both reflective and formative elements in
its structure. It reached structural validity in those separate concepts
that were based on a reflective model. This study revealed interesting
connections between different aspects of the Abilitator and produced
valuable information for further  modification of the
questionnaire.