| Recommended feature | Number of higher quality studies evaluating training including feature | Number of higher quality studies evaluating training without feature | Not reported | Number of lower quality studies evaluating training including feature | Number of lower quality studies evaluating training without feature | Not reported |
| Engaging informal supporters in the issue of domestic abuse | Mandatory training | 1 [56] | 2 [54, 60] | 1 [58] | 0 | 2 [57, 62] | 0 | Acknowledge discomfort | 0 | 0 | 4 [54, 56, 58, 60] | 0 | 0 | 2 [57, 62] |
| Training content and materials | Curricula content includes (a) warning signs and nature of domestic abuse | 4 [54, 56, 58, 60] | 0 | 0 | 2 [57, 62] | 0 | 0 | Curricula content includes (b) impacts | 2 [58, 60] | 0 | 2 | 1 [62] | 0 | 1 [57] | Curricula content includes (c) how to respond and local resources | 4 [54, 56, 58, 60] | 0 | 0 | 2 [57, 62] | 0 | 0 | Tailored training | 4 [54, 56, 58, 60] | 0 | 0 | 1 [57] | 1 [62] | 0 | Diverse representation in materials but without stereotyping | 1 [58] | 0 | 3 [54, 56, 60] | 0 | 0 | 2 [57, 62] | Use nontext formats in materials | 2 [54, 58] | 0 | 2 [56, 60] | 1 [62] | 0 | 1 [57] |
| Training delivery | Work alongside domestic abuse sector | 1 [60] | 3 [54, 56, 58] | 0 | 2 [57, 62] | 0 | 0 | Diverse attendees (experience, sector) and group learning formats | 1 [60] | 1 [58] | 2 [54, 56] | 1 [62] | 1 [57] | 0 |
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