| Resumen: |
The OTS Cohort is an observational open cohort study of salaried workers aged 25 years or older in Spain, designed to examine longitudinal relationships between labor management practices, workrelated psychosocial risks, and health. This cohort profile describes the study design, recruitment procedures, data collection, participation status definitions, response rates and sample attrition patterns across annual survey waves. Participants were recruited from a contact list of 9,913 members of Comisiones Obreras, Spain's largest trade union, who had previously agreed to be contacted for future work-related research. The cohort included two baseline recruitment waves, conducted in 2023 and 2024, followed by annual online survey waves carried out during the first quarter of each year. Invitations were sent by email and included a link to a self-administered questionnaire, with up to two reminders sent at approximately two-week intervals. A total of 3,739 participants entered the cohort: 3,174 in 2023 and 565 in 2024. When calculated over participants in the previous wave, response rates were 68. 5% in 2024, 65. 9% in 2025, and 71. 9% in 2026. When pending participants were also included in the denominator, defined as those who had participated two waves earlier but not in the immediately preceding wave, response rates were 57. 1% in 2025 and 63. 6% in 2026. Re-engagement was observed among pending participants who responded again in the following wave, accounting for 31. 7% of pending participants in 2025 and 42. 6% in 2026. Analytical eligibility was assessed at each wave among respondents according to their current labor market situation. Eligible participants included salaried workers currently at work, salaried workers on sickness absence, and participants who had responded in the previous wave and became unemployed during the following year. Permanent losses were defined as explicit withdrawal, full retirement, permanent disability, or non-response in two consecutive waves. The recruitment strategy and follow-up process should be considered when interpreting findings. The OTS Cohort is not representative of the overall salaried working population in Spain, since participants were recruited from a trade-union contact list, had previously agreed to be recontacted, were aged 25 years or older, and participated voluntarily through an online questionnaire. Accordingly, the cohort should not be used to estimate population prevalences or to describe the distribution of work-related exposures or health outcomes among salaried workers in Spain. Its primary purpose is to support longitudinal analyses of relationships between labor management practices, work-related psychosocial risks, and health. In this context, selection and attrition processes are relevant insofar as they may affect estimated associations, particularly if participation or loss to follow-up is related to both exposures and outcomes. Overall, attrition-related bias appears to be limited, as standardized differences between participants and non-participants across follow-up waves were generally small. Nevertheless, participants retained over time tended to show somewhat more favorable employment conditions, particularly regarding The OTS Cohort on Work Organization and Health: a cohort profile (POWAH Working Paper Series, No. 1) 3 whether salary covered basic needs. This may reflect selection processes during follow-up, but also expected changes over time as some workers move toward more stable employment situations. In addition, there was some indication of a possible healthy worker selection effect, since participants who discontinued follow-up tended to report slightly poorer health status than those who remained in the cohort. Taken together, these patterns suggest that attrition bias is likely very low overall, although it cannot be considered entirely negligible when interpreting longitudinal associations between workrelated exposures and health outcomes. The OTS Cohort provides a longitudinal resource for studying changes in work organization, psychosocial risks at work, and health among salaried workers in Spain. This working paper establishes the methodological basis for future studies using the cohort and provides standardized definitions and indicators to support transparent reporting of recruitment, response rates, analytical eligibility, sample attrition, and potential selection processes. |
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identificación
(Universitat Autònoma de Barcelona. Departament de Pediatria, Obstetrícia i Ginecologia i de Medicina Preventiva i Salut Pública)
