High False-Positive Rate of a Putative Biomarker Test to Aid in the Diagnosis of Schizophrenia

Objective: The current study determined the ability of a 51-analyte immunoassay panel to discriminate between subjects with chronic schizophrenia and healthy control subjects in an American population.

Methods: Serum samples were collected from 25 subjects with a DSM-IV-TR diagnosis of schizophrenia and 50 healthy control subjects. Blinded samples were sent to the RulesBaseMedicine (RBM) laboratory, which analyzed the 51 biomarkers and converted the results into the VeriPsych score by the application of RBM-determined decision rules and returned these scores to the investigators. The VeriPsych score yields a conditional probability ranging from strongly positive to strongly negative that the sample was from someone who had schizophrenia. Sensitivity and specificity were calculated for these data. The study was conducted between February 27, 2010, and August 31, 2011.

Results: On the basis of this test, the conditional probability of having schizophrenia ranged from 35% to 98% in the subjects previously diagnosed with schizophrenia and ranged from < 12% to 99% in the healthy control subjects. The sensitivity of this 51-plex biomarker was 89% in this study, while the specificity was 34%.

Conclusions: The current study confirms that the 51-plex test performs as expected in individuals with chronic schizophrenia (sensitivity = 89%), indicating that the abnormalities in this multiple biomarker test persist and are not affected by the number of years this illness has been present or by its treatment. However, there was a high false-positive rate in healthy control subjects in our sample, leading to a low specificity rate of 34%. Due to the high false-positive rate in our normal controls, this biomarker test was not able to discriminate between healthy control subjects and subjects with chronic schizophrenia in our sample.