Table 2.

Procedures for recruitment of sick-listed workers in Co-WORK study

Recruitment procedures	Explanation
1. Invitation by Dutch SSA	Workers without a (permanent) employment contract who had applied for a sickness benefit at the SSA because of mental health problems and were belonging to one of the participating SSA offices, received an invitation package from the medical advisor of the SSA 1–2 weeks after sick-listing
	The package included an invitational letter, a flyer with information about the study, a consent form for contact, a screening questionnaire and a return envelope
	The sick-listed workers were invited to fill out the forms, and send these back to the researchers
2. First check of eligibility by screening questionnaire	The returned screening questionnaires were assessed by the researcher or a research assistant for a first check of eligibility
3. Screening for in- and exclusion criteria by telephone	The sick-listed workers with a positive screening result were contacted by the researcher by telephone to give more information about the study and to screen for (other) in- and exclusion criteria
	Sick-listed workers who were screened positive and were willing to participate, were invited to an intake meeting at the SSA
4. Intake meeting at SSA office	Prior to the intake meeting, the sick-listed workers received a brochure with detailed information about the study procedures
	The sick-listed worker was included in the study, after signing informed consent and completion of the baseline questionnaire
	After inclusion, randomization and allocation of the sick-listed worker to the control- or intervention group was performed