Table 1 Types of questions about healthcare interventions that overviews can examine^a

1

Different interventions for the same condition or population.

2

Different approaches to the application of the same intervention for the same condition or population.

3

Same intervention for different conditions or populations.

4

Adverse effects of an intervention for one or more conditions or populations.

5

The same intervention for the same condition or population, where different outcomes or time points are addressed.