To evaluate the efficacy of risperidone long-acting injectable (RLAI) for reducing negative symptoms of schizophrenia in patients with predominantly negative symptoms at baseline.

This subanalysis on data from the 6-month, open-label Switch to Risperidone Microspheres (StoRMi) trial included patients with Positive and Negative Syndrome Scale (PANSS) negative subscale score >= 21, which was higher than their PANSS positive subscale score. Improvement in negative symptoms was assessed on the PANSS negative subscale and the negative factor score based on [1]. Additional outcome variables included measures in general functioning, quality of life, and patient satisfaction.

A total of 842 patients were eligible for inclusion in this subanalysis. Six months of treatment were completed by 631 (74.9%) patients. 43 (5.1%) patients discontinued treatment due to an adverse event. Negative symptoms were significantly reduced by 6.1 +/- 6.3 points for the PANSS negative score and 6.1 +/- 6.4 points for the negative factor score1, (P<0.0001 for both). Significant improvements were also noted for total PANSS and other PANSS subscale scores, general functioning, quality of life, and patient satisfaction (P<0.0001). The most common treatment-emergent adverse events (>5%): anxiety (6.8% of patients), exacerbation of disease (6.2%), and insomnia (5.7%). Overall RLAI was well tolerated and associated with significant reductions in movement disorder severity.

RLAI treatment resulted in significant improvement in negative symptom severity and was well tolerated in patients with predominantly negative symptoms, who switched from a stable antipsychotic regimen.