| Study | Reason for exclusion |
|---|---|
| Bergstrom 1999 | Allocation: randomised. Participants: healthy people. |
| Kinon 2001 | Allocation: not randomised, open label study. |
| Wright 1999a | Allocation: not randomised, open label study. |
| Wright 1999b | Allocation: not randomised, open label study. |
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