• Time to recurrence, defined as the time between randomization to treatment in the double-blind period and the first documentation of a recurrence.
  

• Change in PANSS total and subscale scores from randomization to each visit and to the end of the study. Change from baseline in CGI-S at each assessment time point and at endpoint. Incidence of adverse events throughout study.
  

Paliperidone ER is currently being investigated as treatment for the acute symptoms of schizophrenia and also as maintenance treatment. This trial is designed to evaluate efficacy and safety of paliperidone ER in prevention of recurrence of psychotic symptoms in patients with schizophrenia. This trial is a randomized (patients will be assigned to different treatment groups based solely on chance), double-blind (neither the patient nor the physician will know if placebo or drug is being given and at what dose), placebo-controlled, parallel-group, multicenter study consisting of 5 phases: a screening phase of up to 5 days; a 8-week open-label run-in phase, during which all patients will be treated with open-label, flexibly dosed paliperidone ER (3 to 15 mg) orally once daily to identify a dose that will achieve control of their acute psychotic symptoms (only patients who maintain a stable dosage regimen and have a total Positive and Negative Syndrome Scale [PANSS] score </=70; Clinical Global Impression Scale - Severity [CGI-S] </=4; and scores of </=4 for PANSS items for delusions, conceptual disorganization, hallucinatory behavior, suspiciousness/persecution, hostility, and uncooperativeness during the last 2 weeks of the run-in phase will be eligible to continue in the stabilization phase); a 6-week open-label stabilization phase, patients who maintain control of their acute psychotic symptoms at the paliperidone ER dosage identified during the run-in phase and meet the total PANSS score, CGI-S, and PANSS items scores throughout the stabilization phase will be randomized to receive either flexibly dosed paliperidone ER, starting at the dose maintained during the stabilization phase of the study, or placebo; a double-blind treatment phase of variable duration, during which patients will be followed until they meet either defined criteria for recurrence or the study ends; a 52-week open-label extension phase for patients who experience a recurrence event during the double-blind phase of the study, or who remain recurrence free for the entire double-blind phase of the study. Efficacy will be assessed using the PANSS and CGI-S scores that will be collected every week, every 2 weeks, or every 4 weeks throughout. Safety assessments include the incidence of adverse events throughout the study; measurement of vital signs (orthostatic pulse rate, orthostatic blood pressure, and temperature); and clinical laboratory tests.

In the run-in, double-blind, and open-label extension phases of the study, paliperidone ER or matching placebo will be flexibly dosed in the range 3 to 15 mg orally once a day (3, 6, 9, 12, or 15 mg/day). The dosage in the stabilization phase will be fixed throughout at the dosage that achieved symptom control in the run-in phase.