Abstract: We included eleven RCTs involving 1836 caregiver participants. Nine interventions were delivered directly to the caregiver. Seven of these provided support in the caring role, another involved a family life review, and one grief therapy. None provided practical support. The other two interventions aimed to support caregivers indirectly via patient care. Overall the risk of bias is unclear, as all trials under-reported methods. There is low quality evidence that interventions directly supporting the caregiver significantly reduce psychological distress in the short term (8 trials: standardised mean difference (SMD) -0.15; 95% confidence interval (CI) -0.28 to -0.02). There is also low quality evidence that these interventions in the short term may marginally improve coping skills and quality of life, but neither results were statistically significant (7 trials: SMD -0.05; 95% CI -0.24 to 0.14; 6 trials: SMD 0.08; 95% CI -0.11 to 0.26, respectively). One study assessed physical outcomes, specifically sleep improvement, and found no difference (median effect 0.00). No study measured health service use or adverse outcomes. In one study, however, a subgroup of intervention participants had higher levels of family conflict. Evidence was less clear on the indirect interventions. While both trials in this category found that supporting the patient may reduce psychological distress, none of the four assessments were statistically significant. There were no evaluations of coping with the caring role, quality of life, service use or adverse outcomes. In one trial there was no difference between trial arms in the proportion of caregivers reporting good physical health. There is evidence that supportive interventions may help reduce caregivers' psychological distress. These findings suggest that practitioners should enquire about the concerns of caregivers and should consider that they may benefit from additional support. There is, however, a need for further research to explore the benefits identified, and to assess the interventions' effects on physical health, and potential harms. Trials need to report their methods fully.

Plain-language summary: We found 11 trials involving 1836 caregiver participants in total. The trials commonly evaluated an intervention that provided emotional support and advice on coping. Two studies aimed to help support the family and friends indirectly by addressing the needs of the patient. Apart from one trial providing patient care, none provided practical support. Trials compared those who received the intervention with those who did not, to see if the intervention helped the family, family member or friend cope with their caring role. Trials commonly evaluated the intervention by measuring whether it improved the caregiver's general wellbeing. The review found that interventions that directly support the family and/or friends help them to cope emotionally, and may help them to cope with their role in caring and improve their quality of life. There were few assessments of the impact of the interventions on physical health; one study found overall no difference in sleep improvement. No study looked at whether the interventions increased or decreased the carers' health service use or looked for potential harms, although higher levels of family conflict was identified in some participants in one trial. Interventions that aimed to help support the family and/or friends indirectly via patient care, may also help them cope emotionally. There were no assessments on whether the indirect interventions helped them cope with their role in caring, improved quality of life, increased or decreased their health service use, or had potential harms. In one of these trials there was no difference in caregiver physical health between those whose friend or relative had received the additional patient care, and those who had not. The findings of some studies included in this review may be at risk of bias, because they under-report key design features and may have been conducted poorly.