Accuracy of diagnoses of schizophrenia in Medicaid claims.

Medical insurance claims are increasingly important as a source of data in monitoring health care utilization and patient outcomes and in identifying patient cohorts for research. In a study that attempted to verify that those with Medicaid claims for treatment of schizophrenia did indeed have the disorder, two psychiatrists evaluated clinical information obtained from primary mental health care providers in relation to DSM-III-R criteria. The psychiatrists classified 86.8 percent of 319 patients with claims for treatment of schizophrenia and 27.5 percent of 156 patients with claims for treatment of other psychiatric diagnoses as definitely or probably having schizophrenia. The authors conclude that most diagnoses of schizophrenia listed on Medicaid claims are accurate, but that a substantial number of individuals with schizophrenia may not be identified by claims data.