Organic Psychosis Causing Secondary Schizophrenia in One-Fourth of a Cohort of 200 Patients Previously Diagnosed With Primary Schizophrenia

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Objective: To identify the prevalence of secondary schizophrenia (organic psychosis causing a schizophrenia-like syndrome) in patients with a prior diagnosis of schizophrenia presenting to Centro Hospitalar Psiquiátrico de Lisboa, Lisbon, Portugal.

Methods: Two hundred files were retrospectively assessed through paper and electronic records of patients admitted to the hospital with an International Classification of Diseases, Ninth Edition diagnosis of schizophrenia (eg, code 295.x) in a 1-year time span (September 1, 2015–September 1, 2016).

Results: One-fourth of patients (n = 50, 25%) received a new organic psychosis (secondary schizophrenia) diagnosis: epilepsy-related schizophrenia-like psychosis (9.5%), dementia-related schizophrenia-like psychosis (9.5%), brain mass (3.5%), stroke-related schizophrenia-like psychosis (2.0%), and encephalitis-related schizophrenia-like psychosis (0.5%). Among patients with organic psychosis (secondary schizophrenia), the mean delay until correct diagnosis was 12 years.

Conclusions: The most striking feature of this study was the high prevalence of incorrect diagnosis of schizophrenia, with patients not receiving the minimum correct assessment before that diagnosis, resulting in negative consequences. Caution is recommended when diagnosing severely psychotic patients independent of their acute or chronic condition.

Prim Care Companion CNS Disord 2020;22(2):19m02549