Table 1.

Checklist of methodological quality

Study objective
1	Positive if a clearly stated objective is described
Study population
2	Positive if the main features of the study population are clearly described
3	Positive if the inclusion and exclusion criteria are described
Outcome
4	Positive if a clear definition of retirement (timing) is given
5	Positive if outcome source is register-based
Determinants
6	Positive if adjusted for other confounders/determinants from different scientific fields
7	Positive if age (if possible), gender (if possible) and education are taken into account as confounders
Analysis and data evaluation
8	Positive if appropriate statistical model is used to evaluate data
9	Positive if effect size of variables was presented or p-value 0.05 was shown or can be calculated