Most patients diagnosed with DSM-IV schizoaffective disorder are later diagnosed with a different disorder, and that disorder is more stable over time than the DSM-IV schizoaffective disorder diagnosis.In April 2009, Carpenter and the DSM-5 schizoaffective disorder workgroup reported that they were "developing new criteria for schizoaffective disorder to improve reliability and face validity," and were "determining whether the dimensional assessment of mood [would] justify a recommendation to drop schizoaffective disorder as a diagnostic category." Speaking to an audience at the May 2009 annual conference of the American Psychiatric Association, Carpenter said:
We had hoped to get rid of schizoaffective [disorder] as a diagnostic category [in the DSM-5] because we dont think its [a] valid [scientific entity] and we dont think its reliable. On the other hand, we think its absolutely indispensable to clinical practice. A major reason why DSM-IV schizoaffective disorder was indispensable to clinical practice is because it offered clinicians a diagnosis for patients with psychosis in the context of mood disorder whose clinical picture, at the time diagnosed, appeared different from DSM-IV "schizophrenia" or "mood disorder with psychotic features".
Poorly trained clinicians used the diagnosis without making necessary exclusions of common causes of psychosis, including some prescribed psychiatric medications. Specialty books written by experts on schizoaffective disorder have existed for over eight years before DSM-5 describing the overuse of the diagnosis.Carpenter and the DSM-5 schizoaffective disorders workgroup analyzed data made available to them in 2009, and reported in May 2013 that:
a recent review of psychotic disorders from large private insurance and Medicare databases in the U.S. found that the diagnosis of DSM-IV schizoaffective disorder was used for about a third of cases with non-affective psychotic disorders. Hence, this unreliable and poorly defined diagnosis is clearly overused. As stated above, the DSM-IV schizoaffective disorder diagnosis is very inconsistently used or unreliable. A diagnosis is unreliable when several different mental health professionals observing the same individual make different diagnoses excessively. Even when a structured DSM-IV diagnostic interview and best estimate procedures were made by experts in the field that included information from family informants and prior clinical records, reliability was still poor for the DSM-IV schizoaffective diagnosis.The DSM-IV schizoaffective diagnosis is not stable over time either. An initial diagnosis of schizoaffective disorder during time spent at a psychiatric inpatient facility was stable at 6-month and 24-month follow ups for only 36% of patients. By comparison, diagnostic stability was 92% for schizophrenia, 83% for bipolar disorder and 74% for major depression.