Psychosocial adversity captured by ICD-10 Z-codes and mortality risk: evidence from the UK Biobank.

Psychosocial adversity is a major determinant of health, but the mortality associations of its clinical documentation via ICD-10 Z55-Z65 codes remain unclear. We conducted a matched cohort study of UK Biobank participants with linked Hospital Episode Statistics and mortality records. Participants with ≥ 1 ICD-10 Z55-Z65 code recorded between 2010 and 2020 were propensity score-matched (1:1) to hospitalized participants without Z-codes. Mortality follow-up occurred from 2020 to 2023. Associations with all-cause mortality were estimated using Cox proportional hazards models, and cause-specific mortality using Fine-Gray subdistribution hazard models accounting for competing risks. The matched cohort included 13,604 participants (6802 with Z-codes and 6802 without). During a mean follow-up of 3.75 years, mortality rates were 50.8 versus 22.9 deaths per 1000 person-years among participants with and without Z-codes, respectively. Z-code documentation was associated with higher all-cause mortality (HR = 2.02, 95% CI = 1.82, 2.23). Elevated risks were observed across major causes of death, with the strongest association for housing and economic hardship (Z59). Hospital documentation of psychosocial adversity (ICD-10 Z55-Z65 codes) was associated with substantially higher mortality and may contribute to population health surveillance when integrated into electronic health records.