Prospective associations between fixed term contract positions and mental illness rates in Denmark's general workforce: a cohort study protocol

Resume

BACKGROUND: In 2018, 14% of employees in EU had fixed term contracts. Fixed term contract positions are often less secure than permanent contract positions. Perceived job insecurity has been associated with increased rates of mental ill health. The association between fixed term contract positions and mental ill health is, however, uncertain. A recent review have concluded (i) that the quality of most existing studies is low and (ii) that the results in the few studies with sufficient quality are contradictory.

OBJECTIVE: The present project aims at estimating incidence rate ratios of psychotropic drug usage and psychiatric hospital treatment. These ratios will be considered, firstly, in relation to the contrast "fixed term vs. permanent contract" and, secondly, to "fixed term contract vs. unemployment".

METHODS: Interview data with baseline information on employment status from the Danish Labor Force Surveys in the years 2001-2013 will be linked to data from national registers. Participants will be followed for a period of up to five years after the interview. Poisson regression will be used to estimate incidence rate ratios for psychiatric hospital treatment for mood, anxiety or stress-related disorders and redeemed prescriptions for psychotropic drugs, as a function of employment status at baseline. The following contrasts will be considered: (i) Fulltime temporary employment vs. fulltime permanent employment; (ii) temporary employment (regardless of weekly working hours) vs. unemployment. The analyses will be controlled for a series of possible confounders. People who received sickness benefits, received social security cash benefits, redeemed a prescription for psychotropic drugs or received psychiatric hospital treatment for a mental disorder sometime during a one-year period preceding baseline will be excluded from the study. The study will include approximately 134,000 participants (13,000 unemployed, 106,000 with permanent contract and 15,000 with fixed term contract). We expect to find approximately 16,400 incident cases of redeemed prescriptions of psychotropic drugs and 2150 incident cases of psychiatric hospital treatment for mood, anxiety or stress-related disorders.

RESULTS: We expect the analyses to be completed by the end of 2021 and the results to be published mid-2022.

CONCLUSIONS: The statistical power of the study will be large enough to test the hypothesis of a prospective association between fixed term contract positions and mental illness in the general workforce of Denmark.

CLINICALTRIAL:

Reference

Hannerz H, Burr H, Soll-Johanning H, Nielsen ML, Garde AH, Flyvholm M. Prospective associations between fixed term contract positions and mental illness rates in Denmark's general workforce: a cohort study protocol. JMIR Research Protocols 2021;10(2):e24392.
doi: 10.2196/24392

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