Psychoeducational family intervention (PFI) has been proposed to supplement pharmacotherapy in order to improve the clinical outcome of people with bipolar I disorder. Only a few studies have been carried out on the efficacy of PFI on patients' social functioning and on relatives' burden.

to improve patients' social functioning and to reduce the level of family burden in relatives of people with bipolar I disorder.

to improve clinical outcome and social functioning of patients with bipolar I disorder, and to reduce family burden, in those receiving the experimental intervention compared with treatment as usual (TAU) group.

A multicentre, real-world, randomized, controlled, outpatient trial was carried out in 11 Italian mental health centres. Enrolled patients and key-relatives were consecutively allocated either to receive PFI and TAU or to a waiting list receiving TAU alone.

70 families were allocated to the experimental group and 67 to the control group. At the end of the intervention, a significant improvement in patients' clinical status and social functioning was found in the experimental group compared to TAU, as well as a significant reduction in the levels of relatives' subjective and objective burden. The effect of the intervention remained significant also after controlling for several confounding patient's socio-demographic and clinical factors.

PFI is effective in improving the clinical and social outcomes of patients with bipolar I disorder and of their relatives.