| Date | Event | Description |
|---|---|---|
| 10 May 2012 | New citation required and minor changes | New author added, one author withdrew. |
| 10 April 2012 | Amended | Change to the protocol title Minor revisions made to the objective, types of interventions, types of studies and outcomes. A statement that we will analyse each type of intervention separately has been included. Embase and CENTRAL search strategies added. |
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