This is a prospective, non-interventional, multicentre study designed to collect information about the effectiveness, safety and tolerability of Risperidone ISM in patients diagnosed with schizophrenia who are suffering an acute exacerbation, according to routine clinical practice.

This is a non-interventional, multicentre, prospective study conducted in psychiatric inpatient units, and designed to collect information about the effectiveness, safety and tolerability of Risperidone ISM in patients diagnosed with schizophrenia and who are suffering an acute exacerbation, according to routine clinical practice.

The study comprises five visits in total:

Baseline Visit: This visit must be conducted within 48 hours after the first injection of Risperidone ISM. During this visit, the patient must meet all inclusion and exclusion criteria and sign the Informed Consent Form.

Follow-up Visit I: Scheduled approximately 8 ± 2 days after the first injection.

Follow-up Visit II: Scheduled approximately 28 ± 2 days after the first injection.

Discharge Visit: Conducted on the day of discharge, which may vary depending on the individual patient.

Final Visit: Occurs approximately 28 days after the second injection of Risperidone ISM and may be conducted in person or via telephone.

The study will be conducted in five visits: the Baseline Visit is the day on which the patient fulfils the inclusion and exclusion criteria, including signature of the Informed Consent; two follow-up visits will be scheduled after the first injection of Risperidone ISM; in addition, there will be another visit on the day of discharge; and the Final Visit will occur approximately 28 days after the 2nd injection of Risperidone ISM.

The primary objective of the study is to assess, under usual clinical practice, the effectiveness of Risperidone ISM in patients hospitalised due to a schizophrenia relapse.

The secondary objectives include:

Analysis of patterns of use of Risperidone ISM in hospital settings across several European countries.

Characterisation of patient profiles treated with Risperidone ISM in routine clinical practice.

Assessment of social functioning in schizophrenia patients treated with Risperidone ISM.

Evaluation of duration of hospitalisation across participating countries. Measurement of patient-reported treatment satisfaction. Evaluation of safety and tolerability of Risperidone ISM in routine clinical practice.

To assess these objectives, the following scales will be used:

PANSS-6: Baseline visit, Follow-up Visit I, Follow-up Visit II, and Final Visit.

CGI-S: Baseline visit, Follow-up Visit I, Follow-up Visit II, and Final Visit. PSP: Baseline visit, Follow-up Visit II, and Final Visit. MSQ: Baseline visit, Follow-up Visit II, and Final Visit.

Approximately 1,200 adults' patients were calculated to be enrolled in the sites from the participating countries.

The initial sample size estimation relied on an extremely small effect size that would be very unlikely given the results on a previous clinical trial with Risperidone ISM. After the examination of preliminary trial data and considering that the recruitment period was going to be longer than expected (mostly related to administrative issues for activating sites), the Sponsor has decided to re-evaluate the sample size required for the study. For this new estimation, the objective was to calculate the sample size that would allow to perform the analyses of the primary effectiveness variables not only in the total study population, but also in the subgroups who were pre-specified in the study protocol. Accordingly, the estimation was adjusted for each of the subgroups estimated share of the total study sample, and then accounted for the expected loss of patients, that was adjusted upwards to 35%. After that, the new sample size was set at approximately 272 patients.

Inclusion Criteria:

1. Patient aged 18 years or older at the time of hospitalisation.
2. Patient with diagnosis of schizophrenia, as per clinical judgment.
3. Patient admitted to a psychiatric inpatient unit due to an acute exacerbation.
4. Patient has started treatment with Risperidone ISM within the previous 48 hours, according to the current Summary of Product Characteristics (SmPC).
5. Patient or their legal representative provides written informed consent to participate in the study.

Exclusion Criteria:

1. Patient with a diagnosis of schizoaffective disorder, bipolar disorder mental retardation, or other cognitive and neurodevelopmental disorders.
2. Patient with substance-induced psychosis or psychosis during intoxication (patients with comorbid substance abuse/dependence are allowed).
3. Patient unable to answer the study questionnaires.
4. Patient who is currently participating in another clinical study.
5. Patient pregnant or breast-feeding.
6. Patient with a serious and unstable medical condition, forensic patients, or patients with any contraindication mentioned in the SmPC of Risperidone ISM.
7. Patients currently on antipsychotic treatment with clozapine or any long-acting injectable antipsychotic.

Patients aged 18 diagnosed with schizophrenia who are admitted to a psychiatric unit due to a relapse and initiate treatment with Risperidone ISM (OKEDI®), according to the therapeutic indication of the marketing authorization ("Treatment of schizophrenia in adults for whom tolerability and effectiveness has been established with oral risperidone") under routine clinical practice.