Table 1 Experimental/statistical methods to evaluate the EV of RCTs

1. Comparing differences of characteristics and/or NNT analysis from not-enrolled eligible patients with enrolled patients [49–52]

2. Conduction of observational studies to assess the “real world” applicability of RCTs [20, 53, 54]

3. Meta-analysis of patient characteristics data from RCTs [55, 56]

4. Comparison of data from RCTs with data from health record database and/or other epidemiological data:

a) retrospectively [55–59]

b) simulation-based (a priori and retrospective) [60, 61]

5. Review of exclusion criteria in RCTs which would limit the EV [62]