Long follow-up needed after acute or transient psychotic disorder diagnosis

Jan 8 2014

By Eleanor McDermid, Senior medwireNews Reporter

The validity of the International Classification of Diseases (ICD)-10 category of acute and transient psychotic disorders (ATPD) is debatable, say researchers who found that around half of patients moved to a different category within a few years.

Over a 4-year period, just 53.9% of patients who initially fell into the ATPD category continued to do so. The most common diagnostic shift was to schizophrenia, which occurred in about one in eight patients.

“Hence, acute onset and full recovery within 1–3 months do not seem to be always associated with long-term favourable outcome,” say study author David Semple (Hairmyres Hospital, East Kilbride, Glasgow, UK) and co-workers.

They note that, on including the category in ICD-10, the World Health Organization acknowledged that the ideal classification of such disorders is unclear.

The 2923 patients in the study were given an ATPD diagnostic code in hospitals throughout Scotland between 1997 and 2010, equating to an ATPD rate of 4.1 per 100,000 people/year, and making it a relatively rare entity. During follow-up, 46.3% of patients remained in the ATPD category, and 12.6% shifted to a schizophrenia diagnosis. Other relatively common diagnostic shifts were to depressive episodes, in 5.4% of patients, and to recurrent ATPD episodes, in 7.6%.

This latter finding lends “support to the view that some still poorly defined acute and rapidly remitting psychoses are not merely prodromal phases of affective or schizophrenic psychoses but a separate clinical entity,” the researchers write in the British Journal of Psychiatry.

There were slightly more men, at 54.5%, than women, and they were younger, at an average 33.8 versus 41.8 years. Among the 369 patients who converted to a schizophrenia diagnosis, men did so sooner than women, at an average of 1.48 versus 2.15 years.

Schizophrenia converters were also younger, on average, than other patients, at 30.4 versus 40.1 years, and the duration of their first period in hospital tended to be longer.

But the team says: “Even though the presence of these early predictors should arouse clinical suspicion of later transition to schizophrenia, longitudinal follow-up remains the only reliable method to elucidate diagnosis.”

Among patients who transitioned to schizophrenia, the risk was 80% at 2.8 years and 90% at 4.6 years, suggesting that a lengthy follow-up is required “to confidently exclude a diagnosis of schizophrenia.”

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