People using mental health services without a diagnosis still face significantly higher mortality, study finds

A busy London station

A new study of more than 3.2 million mental healthcare recipients  in South London has found that people who receive mental healthcare without being given a formal diagnosis have substantially higher mortality and lower life expectancy than the general population, challenging assumptions that only people with diagnosed mental illnesses die younger than expected.  

Researchers from King’s College London and South London and Maudsley NHS Foundation Trust analysed ten years of electronic health records. They examined mortality patterns in people with a mental health diagnosis, an unspecified diagnosis, or no recorded diagnosis at all.  

Markedly raised mortality rates 

Over 3.2 million people receiving mental health care between 2015–2024 were included in the study published in  British Journal of Psychiatry. Across all groups, mortality was significantly higher than the local population. However, people with unspecified or no diagnosis, a large but previously overlooked population, still showed markedly raised mortality rates. 

Compared with the general population, annual age and gender standardised mortality ratios (SMRs) were:  

  • 2.25–2.56 times higher for people with a mental health diagnosis 
  • 1.88–2.18 times higher for those with an unspecified diagnosis, 
  • 1.59–1.87 times higher for those without any diagnosis. 

Life expectancy was significantly reduced in all groups, with the greatest number of years of life lost among people with a formal mental health diagnosis, 15.1 years for women; 16.7 for men. People with unspecified or no diagnosis still lost 9 to 14 years of life compared to the general population. Elevated mortality was observed for both natural and external causes of death. 

A hidden population at risk 

The researchers highlight that 29% of people accessing mental health services had no diagnosis recorded, while 13% received an unspecified one. These groups may be: 

  • harder to assess or follow-up, 
  • experiencing distress that doesn’t meet diagnostic thresholds, 
  • seen only briefly by crisis or emergency services, 
  • or falling outside established care pathways. 

Lead author Luce Stewart, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, said:

“Our findings show that excess mortality is not limited to people with diagnosed mental health conditions. People receiving mental health care without a diagnosis still face markedly higher risks than the general population. This is a large group who may be under-recognised, under‑assessed, or moving in and out of services. They warrant far greater attention.” 

Senior author Professor Rob Stewart, Professor of Psychiatric Epidemiology and Clinical Informatics at King’s College London, and  Deputy Lead of the Informatics Theme in the NIHR Maudsley Biomedical Research Centre, added: 

“These results challenge the assumption that a formal diagnosis is required to signal clinical risk. Anyone coming into contact with mental health services, regardless of diagnosis, may be vulnerable. Understanding who these people are, why they are not receiving diagnoses, and how to engage them effectively must be a priority for health services.” 

They used the Clinical Record Interactive Search (CRIS) system, a computer system that allows researchers at the NIHR Maudsley Biomedical Research Centre (BRC) to carry out research using information from South London and Maudsley NHS Foundation Trust clinical records. CRIS is safe and secure, and patients' personal details cannot be accessed by researchers who use it. 

Stewart L, Mueller C, Stewart R, Perera G. Mortality and life expectancy in people receiving mental healthcare without a diagnosis: South London electronic health records linkage study. The British Journal of Psychiatry. Published online 2026:1-7. doi:10.1192/bjp.2026.10616


Tags: Informatics - CRIS -

By NIHR Maudsley BRC at 2 Apr 2026, 12:00 PM


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