DIFFERENTIAL-DIAGNOSIS OF SUBSTANCE-INDUCED PSYCHOSIS AND SCHIZOPHRENIA IN PATIENTS WITH SUBSTANCE USE DISORDERS

We derived a statistical model that discriminates between substance-in duced psychosis (i,e,, DSM-III-R organic delusional disorder or organi c hallucinosis; ODD-OH) and DSM-III-R schizophrenia in patients who ha ve both DSM-III-R psychoactive substance use disorders (PSUD) and prom inent delusions or hallucinations, A sample of 211 PSUD inpatients was divided by year of admission into data sets A and B, each of which wa s divided between those with concurrent schizophrenia and those with c oncurrent ODD-OH, A six-predictor discriminant function correctly clas sified 76.2 percent of all set A patients, including 83.1 percent with schizophrenia, Formal thought disorder and bizarre delusions signific antly predict a diagnosis of schizophrenia, with odds ratios (OR) of 3 .55:1 and 6.09:1, respectively, Suicidal ideation (OR = 0.32:1), intra venous cocaine abuse (0.18:1), and a history of drug detoxification (0 .26:1) or methadone maintenance (0.18:1) demonstrate inverse relations hips with a schizophrenia diagnosis, The model was validated in set B, correctly predicting the diagnostic status of 70.4 percent of patient s (72.5% with schizophrenia), The pattern of presenting symptoms and c linical history differs in patients with psychosis due to PSUD and in those whose psychosis is due to schizophrenia, The model presented her e contributes to the differential diagnosis of schizophrenia and ODD-O H among patients with PSUD.