Table 2.

Criteria list for assessment of the methodological quality of prospective cohort studies [20-22]

Criteria a		I, V/P b	% studies meeting the item
Study population and participation (baseline)
1.	Adequate description of sampling frame, recruitment methods, period of recruitment, and place of recruitmentc	I	64%
2.	Participation rate at baseline at least 80%, or if the nonresponse was not selective	V/P	23%
3.	Adequate description of baseline study sample for key characteristicsc	I	32%
Study attrition
4.	Provision of the exact n at each follow up measurement	I	68%
5.	Provision of exact information on follow-up duration	I	95%
6.	Response at short-term follow-up was at least 80% of the n at baseline and response at long-term follow-up was at least 70% of the n at baseline	V/P	50%
7.	Information on not selective nonresponse during follow-up measurementd	V/P	18%
Data collection
8.	Adequate measurement of retirement status	V/P	23%
9.	Retirement status was assessed at a time prior to the measurement of the health outcome	V/P	86%
10.	Adequate measurement of the health outcome	V/P	64%
Data analyses
11.	The statistical model used was appropriate and point estimates with measures of variability (CI or SE) have been provided	V/P	59%
12.	The number of cases was at least 10 times the number of the independent variables	V/P	100%
13.	Important confounders were identified and there has been adjusted for	V/P	36%
14.	No selective reporting of results	V/P	91%

^aRating of criteria: + = yes; - = no; ? = unclear.

^bI, criterion on informativeness; V/P, criterion on validity/precision.

^cAdequate = sufficient information to be able to repeat the study; + is given only if adequate information is given on all characteristics.

^d+ is given only if nonselective dropout on key characteristics (age, gender, retirement status, health outcomes) is reported in the text or tables.