Two psychiatrists reading the same patient's case will agree on the diagnosis about 55% of the time.
That is the headline finding from an international study in which 1,038 psychiatrists, residents and other physicians in 19 countries assessed written clinical vignettes using the World Health Organization's ICD-10 system.
The study, published in Frontiers in Psychiatry and led by researchers at the University of Copenhagen, calculated an inter-rater reliability of 0.48 on Krippendorff's alpha, which the authors describe as modest.
Put plainly, agreement between two clinicians on the same case happened in roughly half of encounters.
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Where the gap is biggest
Not every condition was equally uncertain. Bipolar disorder cases were correctly identified 94% of the time, obsessive-compulsive disorder cases 92%, and depressive disorder cases 88%.
The problem clustered in schizophrenia-spectrum presentations, where accuracy dropped to between 37% and 54%.
Schizophrenia cases were frequently reclassified by other clinicians as OCD, personality disorder or bipolar disorder.
The overlap is not surprising to clinicians. Symptoms such as obsessive thoughts, unusual beliefs and social withdrawal appear across several diagnostic categories, and the ICD-10 lists more than 200 conditions in all.
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Participants in the study worked from a shortlist of 30 commonly used diagnoses.
Why standardized systems still leave room for disagreement
Reliability has been a central preoccupation of modern psychiatric classification since the American Psychiatric Association's DSM and the WHO's ICD introduced rule-based criteria decades ago.
The new study suggests those criteria have not closed the gap as much as many patients assume.
Different clinicians weigh different features of a presentation, and the same symptom can be read as belonging to more than one condition.
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The authors argue the findings also matter for research. If trial participants are grouped under labels their doctors would disagree about, the reported treatment effects become harder to interpret.
What this means if you are being seen
In the United States alone, SAMHSA reported that 61.5 million adults had any mental illness in 2024, and 32 million of them received treatment.
A diagnosis is often the entry point to specific medications, therapies and disability accommodations, so the label carries real weight.
Patients concerned about their diagnosis can ask the treating clinician which other conditions were considered and why they were ruled out.
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A second opinion, particularly when symptoms sit at the boundary between two disorders, is a routine option.
For anyone with a diagnosis on the schizophrenia spectrum, where disagreement was highest, that conversation is worth pressing rather than assuming the first label is settled.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.