The effectiveness of antipsychotics in preventing relapses and attaining symptomatic remission is a relevant topic of psychopharmacological research. The purpose of the present study was to compare the relapse and symptomatic remission rates during the first year of treatment between low doses of haloperidol and SGAs (olanzapine and risperidone) in drug-naïve first-episode non-affective psychosis individuals. This is a prospective, randomized, open-label study conducted from February 2001 to February 2006. Data for the present investigation were obtained from a large epidemiologic and 3-year longitudinal intervention program of first-episode psychosis (DSM-IV criteria) conducted at the University Hospital Marques de Valdecilla, Santander, Spain. One hundred and seventy four patients were randomly assigned to haloperidol (N = 56), olanzapine (N = 55), or risperidone (N = 63) and followed up for 1 year. Primary effectiveness measures were the time up to relapse and rates of relapse and symptomatic remission. There were no significant differences in the relapse rate between treatments (11.1% haloperidol; 18.5% olanzapine, and 13.8% risperidone) (χ(2) = 1.230; p = 0.541) or in the time up to relapse (Log Rank χ(2) = 0.308; p = 0.857). The rates of relapse for adherent (11.2%) and non-adherent (26.9%) patients were significantly different (χ(2) = 4.215; df = 1; p = 0.040). The remission rate did not differ significantly between treatment groups (χ(2) = 2.760; p = 0.252) and adherence to medication did not seem to significantly influence remission rates. We conclude that haloperidol, olanzapine and risperidone show a similar effectiveness in relapse prevention or in remission attainment during the first year of treatment.
