Clinicians may have missed almost 1 in 4 cases of severe mental illness (SMI) in patients hospitalised in England for other conditions over a recent 10 year period, research suggested.
The study, published in PLOS Medicine, found that people from ethnic minority backgrounds were more likely to be affected.
It called for improved integration of physical and mental health in hospitals.
However, the researchers noted that the situation was improving, as data from 2006 showed that SMI diagnoses were missed in more than half of cases.
"We found encouraging signs that clinicians are more frequently identifying severe mental illnesses in hospital patients than they were a decade ago, but there's a lot more that can be done, particularly to address disparities between ethnic groups, to ensure that everyone gets the best care available," said Hassan Mansour from University College London, who led the study.
Study of Data From South London
The researchers used data from the Clinical Record Interactive Search (CRIS) system, developed for the National Institute for Health Research (NIHR) Mental Health Biomedical Research Centre held at the South London and Maudsley NHS Foundation Trust. They linked records of 13,786 adults with a pre-existing diagnosis of SMI with 45,706 emergency admissions to English general hospitals for the same people between 2006 and 2017, to see whether their diagnosis was recognised on admission for a physical illness.
They found that a diagnosis of SMI had been made in 76.7% of cases.
However, that figure was an improvement from 47.8% recorded in 2006.
The likelihood of diagnosis varied between different mental illnesses. For instance, among patients with schizophrenia spectrum disorders, a category-level diagnosis was recorded in 56.4% of cases, whereas for bipolar disorder the equivalent proportion was 49.7%.
Ethnic Minorities 'Disadvantaged'
The researchers found that people from ethnic minority backgrounds were more likely to have missed diagnoses, particularly those from Black African or Caribbean backgrounds, who were 38% more likely to have their diagnosis unrecorded compared with those from White ethnic backgrounds.
Also, single people were less likely to experience missed diagnosis, the researchers found.
Mr Mansour said: "The disparities we found between ethnic groups are concerning because previous studies have identified particularly poor health outcomes for people from minority ethnic groups with severe mental illnesses.
"Training in culturally sensitive diagnosis may be needed to reduce inequalities in medical care."
Dr Andrew Sommerlad from University College London (UCL) and Camden and Islington NHS Foundation Trust, who was a senior author of the study, said: "If someone with a severe mental illness comes to hospital physically unwell, it might be an indicator that their mental health is getting worse.
"It could be a critical time to identify issues with mental and physical health, and an opportunity to access support for their mental illness."
He added: "It's important to understand that physical and mental health are interlinked and should not be seen as separate entities. Both can impact the other, so more needs to be done to bridge the gap and achieve truly integrated care that's accessible to everyone."
The research was supported by the NIHR Biomedical Research Centres at University College London Hospitals and South London and Maudsley NHS Foundation Trust, and King's College London.