Mortality and life expectancy in people receiving mental healthcare without a diagnosis: South London electronic health records linkage study

BACKGROUND: Increased mortality and reduced life expectancy are well documented among mental healthcare recipients. Whereas clinical research typically focuses on people with specific diagnoses, little is known about those who receive mental healthcare but have an unspecified or no diagnosis. AIMS: Using routinely collected mortality data, we aimed to explore how mortality and life expectancy differed between those with and without a specific mental health diagnosis. METHOD: Using the South London and Maudsley NHS Foundation Trust clinical records interactive search system, we assembled annual cohorts of people who had past or current mental health service receipt between 2015 and 2024. Mortality rates and life expectancy were ascertained for those with mental health diagnoses (ICD-10 F-codes), those with unspecified diagnoses (Z-codes) and those without any diagnosis. Age- and gender-standardised mortality ratios (SMRs) and life expectancy were calculated in relation to the local catchment comparator population. RESULTS: = 3 266 268) of people accessing mental health services, 57.7% had an F-code diagnosis, 13.0% a Z-code diagnosis and 29.3% no diagnosis. Annual SMRs (95% CI) for F-code diagnoses ranged from 2.25 (2.18-2.33) to 2.56 (2.46-2.65); for Z-code diagnoses from 1.88 (1.73-2.02) to 2.18 (2.00-2.36); and for no diagnosis from 1.59 (1.48-1.71) to 1.87 (1.72-2.01). Years of life lost were greatest for those with F-code diagnoses (females, 15.1 years; males, 16.7 years), followed by Z-codes (females, 11.8 years; males, 14.4 years) and no diagnosis (females, 9.4 years; males, 10.6 years). Raised SMRs were observed for both external- and natural-cause mortality for all groups. CONCLUSIONS: People in contact with mental health services with unspecified or no mental health diagnosis have a substantially higher mortality and lower life expectancy compared with the general population. Further research is needed to characterise this group and study other outcomes, because they may fall outside care pathways.