External Causes of Death From Death Certificates in Patients With Dementia

Abstract

Objectives: We aim to analyze the risk of death from specific external causes, including falls, complications of medical and surgical care, unintentional injuries, and suicide, in dementia patients.

Design: Swedish nationwide cohort study integrating 6 registers from May 1, 2007, through December 31, 2018, including the Swedish Registry for Cognitive/Dementia Disorders (SveDem).

Setting and participants: Population-based study. Patients diagnosed with dementia from 2007 to 2018 and up to 4 controls matched on year of birth (±3 years), sex, and region of residence.

Methods: The exposures of this study were diagnosis of dementia and dementia subtypes. Number of deaths and causes of mortality were obtained from death certificates compiled into the Cause of Death Register. Hazard ratios (HRs) and 95% CIs were estimated using Cox and flexible models, adjusted for sociodemographics, medical and psychiatric disorders.

Results: The study population included 235,085 patients with dementia [96,760 men (41.2%); mean age 81.5 (SD 8.5) years] and 771,019 control participants [341,994 men (44.4%); mean age 79.9 (SD 8.6) years], over 3,721,687 person-years. Compared with control participants, patients with dementia presented increased risk for unintentional injuries (HR 3.30, 95% CI 3.19-3.40) and falls (HR 2.67, 95% CI 2.54-2.80) during old age (≥75 y), and suicide (HR 1.56, 95% CI 1.02-2.39) in middle age (<65 y). Suicide risk was 5.04 times higher (HR 6.04, 95% CI 4.22-8.66) in patients with both dementia and 2 or more psychiatric disorders relative to controls (incidence rate per person-years, 1.6 vs 0.3). For dementia subtypes, frontotemporal dementia had the highest risks of unintentional injuries (HR 4.28, 95% CI 2.80-6.52) and falls (HR 3.83, 95% CI 1.98-7.41), whereas subjects with mixed dementia were less likely to die from suicide (HR 0.11, 95% CI 0.03-0.46) and complications of medical and surgical care (HR 0.53, 95% CI 0.40-0.70) compared to controls.

Conclusions and implications: Suicide risk screening and psychiatric disorders management in early-onset dementia and early interventions for unintentional injuries and falls prevention in older dementia patients should be provided.

Keywords: External causes of death; dementia; falls; frontotemporal dementia; psychiatric disorder; suicide.