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| Type of control group | Number of studies |
|---|---|
| Two-arm studies (n = 48) | |
| Active control group | 7 |
| Educational control group | 5 |
| Similar activity with supervision | 1 |
| Usual care | 35 |
| Three-arm studies (n = 5) | |
| Active control group and usual care | 3 |
| Educational control group and usual care | 1 |
| Similar activity with supervision and usual care | 1 |
| Without control group (n = 10) |
