Differentiating childhood-onset schizophrenia from psychotic mood disorders

Objective: The authors systematically examined a sample of patients who wer e referred to an ongoing National Institute of Mental Health (NIMH) study o f childhood-onset schizophrenia (COS), but who received diagnoses of mood d isorders at the NIMH, to analyze the reliability of these research-setting diagnoses and to characterize the patients clinically. Pilot data regarding the clinical course of these patients over a 2- to 7-year follow-up period were also obtained. Method: Thirty-three cases were selected from the 215 pediatric patients who had been screened in person from 1991 to 1999 for ad mission to the COS study. These 33 patients had been excluded from the COS study on the basis of a day-long evaluation, including a structured diagnos tic interview, which yielded a diagnosis of a mood disorder rather than sch izophrenia. This subgroup, together with six COS subjects (for a total N = 39), were included in a diagnostic reliability study in which they were ree valuated by three psychiatrists who were blind to the initial research diag nosis. In addition, pilot follow-up data regarding current function and tre atment status were obtained for 25 of the 33 patients with mood disorders. Results: Overall, the interrater reliability of the three raters was excell ent (kappa = 0.90). Global reliability between these raters and the NIMH re search diagnoses was good (average kappa across diagnoses = 0.61), and agre ement for those patients who had mood disorders was good (86% agreement; ka ppa = 0.60). Pilot follow-up data indicate that none of the subjects with a diagnosed mood disorder developed a clinical course resembling schizophren ia. Conclusions: Many of the patients referred to the NIMH COS study with c linical diagnoses of schizophrenia had psychotic mood disorders diagnosed o n the basis of a comprehensive research evaluation including structured dia gnostic interviews, and these research diagnoses were reliable. The diagnos is of COS is difficult and requires a time-consuming evaluation process.