Effectiveness of dyadic interventions in improving outcomes for adults with multiple long-term conditions or frailty and their informal carers: a systematic review.

Dyadic interventions targeting carer-care recipient pairs are effective in improving psychosocial outcomes in single diseases, but whether similar interventions are beneficial in the context of multiple long-term conditions or frailty remains unclear. In this systematic review, we synthesised evidence on the effectiveness of community dyadic interventions in improving outcomes for adults aged 55 years or older with multiple long-term conditions or frailty, or both, and their informal carers. We searched six databases for experimental and quasi-experimental studies published from Jan 1, 2010 to Sept 25, 2025. Of the 5284 records screened, eight randomised controlled trials (seven with a moderate risk of bias) reporting on seven unique trials and 3630 dyads were included. Dyadic interventions had some beneficial effects on reducing emergency care visits, hospital readmissions, and functional decline in care recipients, and on reducing caregiving burden in carers (low certainty of evidence), but showed little or no effect on quality of life (low certainty of evidence) or mental health outcomes (predominantly very low certainty of evidence) in both care recipients and carers. No trial evaluated effects on social aspects of care or mortality.