Risperidone long acting injection (RLAI) has in recent years gained widespread use in the treatment of schizophrenia and schizoaffective disorder. It is considered safe, tolerable, and the efficacy has been established in several studies. However, all these studies were funded by the manufacturer of RLAI.

To compare the efficiency of RLAI vs. conventional depot antipsychotics (CAD).

This study includes 9197 patients with schizophrenia being treated with depot injections in Denmark from January, 1996 until December, 2007. Prescription data were obtained from the national prescription database which contains information of sold defined daily dosages (DDD).

Of the 9197 patients 1056 had originally received a CAD treatment (zuclopentixole, haloperidol, perphenazine, fluphenazine or flupenthixol), but where switched to RLAI. The two periods were compared with regard to number of admissions and time spent in hospital. A Cox regression analysis of any-cause-discontinuation was performed on 9105 incident depot antipsychotic periods.

When receiving CAD treatment patients had 0.08 (95% CI [0.07; 0.08]) admissions to hospital per month vs. 0.50 (95% CI [0.47; 0.54]) when treated with RLAI. On average the patients spent 33 percent (95% CI [32; 35]) of the time during the CAD-period as admitted to hospital vs. 48 percent (95% CI [46; 50]) during the RLAI-period. Of the 1056 patients 83% where eventually switched back to a CAD.

Furthermore the RLAI patients have a higher hazard of discontinuing their treatment than the CAD patients (HR = 2.26, 95% CI [2.05; 2.48]).

RLAI was inferior compared to conventional depot antipsychotics.