Table 2.
Methodological quality of observational studies.
| Observational studies | The healthy elderly | MCI | Dementia | ||||
|---|---|---|---|---|---|---|---|
| Nyberg et al. 2003 [30] | Clare et al. 2009 [31] | Hampstead 2011 [32] | Belleville et al. 2011 [33] | Nagaya et al. 2005 [34] | Tanaka et al. 2007 [35] | Spironelli et al. 2013 [36] | |
| Definition study population | 0 | 1 | 1 | 1 | 0 | 1 | 1 |
| Selection bias | 0 | 0 | 0 | 1 | 0 | 0 | 0 |
| Intervention description and allocation | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Outcome definition | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Blinded outcome assessments | 0 | 0 | 0 | 1 | 0 | 0 | 0 |
| Completeness dataset/follow-up | 0 | 1 | 1 | 1 | 0 | 1 | 1 |
| Loss to follow | 0 | 1 | 1 | 1 | 1 | 1 | 1 |
| Confounders | 1 | 0 | 0 | 1 | 0 | 0 | 0 |
| Validity and applicability | 0 | 1 | 0 | 1 | 0 | 0 | 1 |
|
| |||||||
| Total | 3 | 6 | 5 | 9 | 3 | 5 | 6 |
| CBO classification | C | C | C | B | C | C | C |
The CBO classification reflects the level of evidence. A1 is a systematic review of at least two independent randomized double blind studies of sufficient quality and size. A2 is a randomized double blind study of sufficient quality and size. B is a comparative study, which does not meet all the criteria of an A2 study. C is a noncomparative study and D is the opinion of experts (http://www.cbo.nl/).