A new international study finds that psychiatrists presented with the same written patient case reach the same conclusion only about 55 percent of the time.
The findings were reported on September 10, 2026, by DR. The study was published in the journal Frontiers in Psychiatry. It examined how consistently doctors assign a psychiatric diagnosis based on identical case descriptions.
A total of 1,038 doctors from 19 countries took part. Each was given two of nine patient cases and asked to diagnose them using the World Health Organization’s ICD-10 system. Overall agreement was 54.9 percent.
Agreement varied sharply between cases. For the case with bipolar disorder as the reference diagnosis, 94 percent chose bipolar disorder. For the OCD case, 92 percent chose OCD.
Cases within the schizophrenia spectrum caused the most disagreement. In some cases, the same symptoms were read as either schizophrenia or OCD. One explanation is that different mental disorders can share symptoms.
Julie Nordgaard, professor of clinical psychiatry at the University of Copenhagen and a lead consultant, described the pattern on DR’s P1 Morgen. Where a case contained signs pointing toward both schizophrenia and OCD, she said, the doctors split almost evenly between the two.
Not the same as misdiagnosis
DR notes that the study measured agreement about written cases. It did not measure how often two psychiatrists reach different conclusions about the same real patient. The results are also international and cannot be transferred directly to Danish psychiatrists.
Practicing psychiatrist Casper Westergaard made the same point on P1 Morgen. He said he recognizes that doubt can arise during the diagnostic process. He does not recognize a situation in which half of all diagnoses are wrong, and said the results cannot be applied directly to how psychiatrists work in practice.
According to Westergaard, diagnoses are not permanent. He described a diagnosis as the best available explanation at a given point in time. He also said psychiatry cannot deliver the certainty of an X-ray confirming pneumonia in a specific lung.
Nordgaard said the correct diagnosis matters a great deal for patients. She pointed to consequences for medication, psychotherapy, and the services and support a patient can access.
The researchers behind the study argue that the level of disagreement should be taken seriously. According to the University of Copenhagen, diagnostic uncertainty can affect both patient treatment and research into mental disorders.
The ICD-10 system used in the study is the international diagnostic framework maintained by the World Health Organization. The nine cases covered a range of conditions, including bipolar disorder, OCD and disorders in the schizophrenia spectrum.
