Long term disability and mental disorders: a prospective cohort study with 1-year follow-up

Mental disorders with a chronic course, such as depression, anxiety disorder or
substance related disorder, are highly prevalent among workers. Moreover, they
often coincide with somatic disorders or other mental disorders, thus causing
long term work disability. Personal and external factors, such as health care
utilization, coping strategies and social support seem to play an important
role in perpetuating long term work disability. However, reliable data on the
prevalence of mental disorders among chronically disabled persons, mental
co-morbidity, course, prognosis of health and functioning, and perpetuating
factors are sparse.

Perpetuating factors associated with long term disability due to mental
disorders are unclear. More knowledge about these factors is needed for
professionals in insurance, occupational and curative healthcare to identify
high-risk groups, to prevent unnecessary long term vocational disability with
effective interventions and to improve societal participation.

The research design is a prospective cohort study of about 1150 persons
claiming disability benefit after 2-year sickness absence at the Dutch
Implementing Institute Employee Insurances (UWV) in Groningen, a northern
province of the Netherlands, with a follow-up period of one year. Procedures
will be tested in a pilot study. Inclusion and data collection starts in
October 2008. The inclusion period is one year. Mental as well as somatic
disorders are included. Diagnosis, functioning, disability, return to work,
care utilization, coping strategies and social support are measured at two
moments, at baseline (t0) and after one year (t1). Participants with a good
prognosis of recovery of health and functioning are measured at a variable
moment (tvar) between t0 and t1. Mental disorders specified at t0 will be
evaluated with a structured psychiatric interview at t1 (and at tvar, depending
on prognosis). Mental disorders developing during follow-up will be detected
after screening at t1 (and at tvar, depending on prognosis). The validity,
reliability and optimal cut-off value of each screening instrument will be
determined using ROC-analysis at t0 against the structured psychiatric
diagnostic interview as external criterion.
Data gathered with the questionnaire and CIDI will be linked to data registered
by UWV concerning impairments, functioning, work, disability and return to
work.

Participation and measurements (questionnaire and psychiatric interview) are
unlikely to cause any significant distress. There are no risks associated with
participation. At any time, respondents can contact the principal investigator
and/or an independent physician. Therefore, the investigator requests
exemption from the obligatory insurance.