Test-retest reliability, measurement invariance, and usability of a condensed physical and psychosocial workplace assessment instrument (WAge Index) among manufacturing and service workers aged 18–65 across three European countries: a prospective observational validation study
Musculoskeletal disorders, psychosocial wellbeing, physical capacity, and workplace health across age groups
Prospective observational study with two measurement time points (T1 and T2), conducted in manufacturing and service workplaces in Portugal, Spain, and Poland. The interval between measurements will be approximately 3 to 6 weeks, depending on company availability. No intervention is introduced between time points. At both time points, participants will complete a condensed questionnaire battery assessing physical exposure (perceived physical load and musculoskeletal symptoms), psychosocial factors (based on the HERO model: organisational practices and resources, employee characteristics, and organisational outcomes), and individual factors (demographics, work characteristics, and age-related variables). The condensed battery is derived from the instruments used in the first cross-sectional study (WAGE-S1) and reduced based on confirmatory factor analysis results. At T2, structured feedback on the usability and acceptability of the assessment instruments will also be collected from participants and organisational stakeholders (Occupational Safety and Health [OSH] managers, Human Resources [HR] representatives, and union representatives) through feedback sessions. Recruitment will follow the same principles as the cross-sectional study, drawing on workforce characteristics provided by each company to ensure representation across job roles, sexes, and age groups. Where possible, participants from the first study will be invited to participate. A minimum of 50 participants per country is targeted, based on power analysis for small to medium effect sizes (power 0.80, α = 0.05) for the primary analyses. Data collection is conducted locally by partner institutions (Faculdade de Motricidade Humana [FMH] in Portugal, Central Institute for Labour Protection - National Research Institute [CIOP-PIB] in Poland, Instituto de Biomecánica (IBV) and the Universitat Jaume I (UJI) in Spain) under their respective ethics approvals. Only anonymised data is shared with SINTEF for int
1. Currently employed in manufacturing or service sector organisations participating in the WAge project in Portugal, Spain, or Poland 2. Correct understanding of the native language 3. Currently performing their work as their main occupation for at least 20 hours per week
1. Pregnancy 2. Acute illnesses, accidents, or other health conditions that currently affect physical capacity 3. Sickness absence on the day of the measurements