Table 1.

Quality assessment criteria

	Application of the criteria to specific study designs	Definition of each criterion
Study objective	All	A specific objective has been clearly formulated.
Study population	All	The response rate is at least 80%.
	Prospective	The response rate is at least 80% after at least one year or the non-responders are not selective.
	Case–control	Cases and controls originate from the same population and there is a clear definition of cases and controls.
Exposure	All	The original ERI questionnaire was used, including the ascertainment of over-commitment.
	All	Data on physical work-related stress was collected and taken into account in the analysis.
Outcome	Case–control	Prospective enrolment was used (identification of new cases and selection of controls occurs at the same time).
	Prospective	Follow-up completed at least one year later.
Analysis	All	Risk predictors including confidence intervals or p-values were calculated and confounding was controlled for.