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Body mass index and mortality in patients with schizophrenia spectrum disorders: a cohort study in a South London catchment area

Research output: Contribution to journalArticlepeer-review

Jianhua Chen, Gayan Perera, Hitesh Shetty, Matthew Broadbent, Robert Stewart

Original languageEnglish
Article numbere100819
Pages (from-to)1-9
Number of pages9
JournalGeneral Psychiatry
Issue numbere100819
Accepted/In press30 Sep 2022
Published4 Nov 2022

Bibliographical note

Funding Information: RS is part-funded by: (1) the National Institute for Health Research (NIHR) Biomedical Research Centre at the South London and Maudsley NHS Foundation Trust and King’s College London; (2) the National Institute for Health Research (NIHR) Applied Research Collaboration South London (NIHR ARC South London) at King’s College Hospital NHS Foundation Trust; (3) the DATAMIND HDR UK Mental Health Data Hub (MRC grant MR/W014386). JC is part-funded by: King's College London-K C Wong Postdoctoral Fellowships, Shanghai Youth Top-notch Talent Support Program, Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support, Shanghai Key Laboratory of Psychotic Disorders (13dz2260500), Shanghai Clinical Research Centre for Mental Health (19MC1911100), Program of Shanghai Academic/Technology Research Leader (21XD1423300), and Shanghai Pujiang Program (21PJD063). GP is funded by the NIHR Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London. Publisher Copyright: ©


King's Authors


People with schizophrenia have a high premature mortality risk. Obesity is a key potential underlying risk factor that is relatively unevaluated to date.
In this study, we investigated the associations of routinely recorded body size with all-cause mortality and deaths from common causes in a large cohort of people with schizophrenia spectrum disorders.
We assembled a retrospective observational cohort using data from a large mental health service in South London. We followed all patients over the age of 18 years with a clinical diagnosis of schizophrenia spectrum disorders from the date of their first recorded body mass index (BMI) between 1 January 2007 and 31 March 2018.
Of 11 900 patients with a BMI recording, 1566 died. The Cox proportional hazards regression models, after adjusting for sociodemographic, socioeconomic variables and comorbidities, indicated that all-cause mortality was only associated with underweight status compared with healthy weight status (hazard ratio (HR): 1.33, 95%confidence interval (CI): 1.01 to 1.76). Obesity (HR: 1.24, 95% CI: 1.01 to 1.52) and morbid obesity (HR: 1.54, 95% CI: 1.03 to 2.42) were associated with all-cause mortality in the 18–45 years age range, and obesity was associated with lower risk (HR: 0.66, 95% CI: 0.50 to 0.87) in those aged 65+ years. Cancer mortality was raised in underweight individuals (HR: 1.93, 95% CI: 1.03 to 4.10) and respiratory disease mortality raised in those with morbid obesity (HR: 2.17, 95% CI: 1.02 to 5.22).
Overall, being underweight was associated with higher mortality in this disorder group; however, this was potentially accounted for by frailty in older age groups, and obesity was a risk factor for premature mortality in younger ages. The impact of obesity on life expectancy for people with schizophrenia spectrum disorders is clear from our findings. A deeper biological understanding of the relationship between these diseases and schizophrenia will help improve clinical practice.

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