ABSTRACT
Introduction: Informal caregivers of people with a mental illness are at increased risk of developing depression, anxiety, and stress, so preventive interventions are needed. Method: The review was reported in PROSPERO (ID: CRD42018094454). The PsycINFO, PubMed, and Scopus databases were searched in June 2019. The Cochrane Risk of Bias and Jadad scale scores were used to assess study quality. Inclusion criteria were: RCTs of informal caregiver interventions regardless of the care receiver's mental illness and intervention modality. Interventions should be compared to a waitlist, treatment as usual or active control, taught in real-time by a mental health professional, include an outcome measure on psychological distress, and published in a peer-reviewed journal article in English. RCTs were excluded if the intervention was given in dyads (caregiver + care receiver), limited to the provision of respite care where the patient sample included a mix of both physical and psychological illnesses, unpublished, not peer-reviewed, study protocols, or dissertations. Results: A total of 2,148 studies were identified; of these, 44 RCT studies met the inclusion criteria, and 31 had sufficient data to conduct a meta-analysis including subgroup analysis (N = 1,899). The systematic review showed that thirty-one out of the 44 RCTs had an effect of the intervention on decreasing psychological distress. The results of the meta-analysis, which included informal caregiver interventions, compared to waitlist, treatment as usual, or active control, regardless of care-receiver mental illness or intervention modality showed a small effect of -0.32 (95% CI -0.53 to -0.11). The heterogeneity of the included studies was high (I 2 = 78). The subgroup analysis included manualized interventions lasting at least 8 weeks and the subgroup analysis that included an active control showed a small effect and low heterogeneity. Lack of active control and long-term follow-up is a limitation of most of the studies. Conclusion: The evidence supports that several interventions improve the mental health of caregivers. Manualized interventions ≥ 8 weeks with active participation are most effective. Future RCTs should improve methodology, and research should investigate which intervention modality is most effective for what kind of caregiver. Future research should clearly specify what the included intervention components are, use longer follow-up times, and conduct mediational analyses to better understand what mechanisms create the effect of an intervention. Systematic review registration: Identifier: CRD42018094454.
