Table 1. Criteria for assessing methodological quality.

A positive score of 1 applied if:

1) Study sample is nationally or regionally representative of the elderly population

2) Sample inclusion and/or exclusion criteria are formulated

3) Information on participants lost-to-follow-up is reported

4) The process of data collection is described (e.g. interview or self-report)

5) Training and quality control methods for interviewers’ technique are applied

6) Definition of the outcome criteria incident depression is provided: e.g. cut-off-score, measuring instrument for depression

7) Descriptive data are provided on depression: e.g. number of incident cases

8) Characteristics of study participants (socio-demographic, clinical, social) are given

9) For each variable of interest, sources of data and details of methods of assessment are given

10) Reliability and/or validity of study instruments is reported

11) Detailed description of statistical analysis is given

12) Adjustment for cognitive status in analyses is made (0 if no information is provided)

13) Individuals living with dementia are excluded from the analysis (0 if no information is provided)

14) Information on non-significant risk factor and protective factor variables is reported

15) Precision of estimates is given (e.g. 95% confidence interval)

16) model is adjusted for potentially relevant cofounders

Table 1 shows all criteria used for assessing the methodological quality of the studies about risk factors or protective factors for depression in individuals 65+. If one of the 17 criteria were met, 1 point was added. If the study did not meet one criterion, 0 points were added. Studies reaching 16 to 14 points were considered as “high quality”, studies reaching 13 to 11 points “medium quality” and studies reaching 10 points or less “lower quality”.