In order to derive such descriptive knowledge from available data, specific methodological criteria have to be met (e.g., representativeness).
As the Lievense et al [ 13] did not include criteria specific to the methodological assessment of randomised controlled trials (RCTs), the PEDro scale was used for the quality assessment of RCTs [ 14].
Studies were included only when they adhered to specific diagnostic criteria for ischemic events and met the published methodological criteria.
All included studies were methodologically assessed with the original Jadad scale and the additional methodological criteria.
Finally, based on strict methodological criteria, only three studies reported robust, but conflicting, results.
✓, fulfilled satisfactorily the methodological criteria (1 check point); ≠, fulfilled partially the methodological criteria (0.5 check point); ✘, did not fulfill the methodological criteria (0 check point).
According to the pre-established methodological criteria, modifying or confounding variables were not identified (Table 3).
Covariance between methodological criteria should also be examined.
No significant improvements were found in adherence to methodological criteria.
Nineteen studies are described with respect to eight methodological criteria.
