The paranoid quotient. A BPRS ratio for exploring subtypes in schizophrenia

A paranoid quotient developed from two items of the Brief Psychiatric Rating Scale, suspiciousness and disorganized speech, is presented as a novel method for estimating the degree of paranoia of chronic schizophrenic patients. The mean quotient for paranoid schizophrenic patients was 70 which significantly exceeded that of non-paranoid patients (mean quotient = 47, P less than 0.002). This difference proved more discriminatory than that obtained by examining the constituent items alone. Hence, the quotient strategy offers a promising way to quantify paranoid symptoms in a population of patients in whom diagnostic subtyping is often difficult.