Supplementary Material for: Polarity Index of Psychological Interventions in Maintenance Treatment of Bipolar Disorder

<b><i>Background:</i></b> Although several adjunctive psychological interventions are effective in the maintenance of bipolar disorders (BD), no attempt has been made to classify them according to their ability to prevent manic versus depressive episodes. Our study aims to rank the adjunctive psychotherapies for the prophylaxis of BD by means of their polarity index (PI). <b><i>Methods:</i></b> Randomized controlled trials comparing the efficacy of a psychological intervention with a comparator in BD maintenance treatment in patients aged over 18 were systematically reviewed. Exclusion criteria were a small sample size, a study sample not exclusively composed of bipolar patients and the absence of a control group. PI is a novel metric indicating the relative antimanic versus antidepressive preventive efficacy of treatments. PI was retrieved by calculating the ratio of the number needed to treat (NNT) for prevention of depression and the NNT for prevention of mania. PI >1.0 indicates a relatively higher antimanic prophylactic efficacy and PI <1.0 a greater antidepressive efficacy. <b><i>Results:</i></b> A total of 9 studies were included. PI was 0.33, 0.63 and 0.89 for cognitive-behavioral therapy, 0.42 for family-focused therapy, 0.73 and 0.78 for psychoeducation, 1 for enhanced relapse prevention, 1.78 for caregiver group psychoeducation and 3.36 for brief technique-driven interventions. With regard to the PI for 1 cognitive-behavioral study, enhanced relapse prevention and brief technique-driven interventions may not be reliable since those trials were negative. <b><i>Conclusions:</i></b> The PI provides a measure of how much depression-preventive or (hypo) mania-preventive an intervention is and may guide the choice of adjunctive psychotherapy in the context of individualized long-term treatment of BD.