Date Published: April 11, 2019
Publisher: BioMed Central
Author(s): Ji Hyun An, Kyung Eun Lee, Hong Jin Jeon, Sang Joon Son, Sung Yoon Kim, Jin Pyo Hong.
The leading causes of death among the elderly with cognitive impairment are unknown. This study aims to estimate the suicide and accidental death rates on the basis of a clinical case registry of patients diagnosed with cognitive impairment.
The target sample consisted of 10,169 patients diagnosed with dementia or mild cognitive impairment (MCI), who were evaluated at the Clinical Research Center for Dementia of Korea (CREDOS) from January 2005 to December 2013. Information about whether the patients had died from suicide or in any kind of accident by December 31, 2016, was obtained from the database of the National Statistical Office (NSO). The standardized mortality ratio (SMR) and Cox-regression analysis were performed for evaluating the risk of suicide and accidental death as identified by the ICD-10.
The average of the Clinical Dementia Rating Scale (CDR) score (0.68 vs 0.93) was lower, and the age at the time of study registration (71.42 vs 75.68 years) was younger in the suicidal death group, as compared to the accidental death group. The overall SMR for accidental death in cognitively impaired patients (1.44, 95% CI 1.22–1.71) was significantly higher than the general population. Later onset (1.43, 95% CI 1.20–1.71) and older age (2.21, 95% CI 1.04–4.68) increased the risk of accidental death in cognitively impaired patients. According to the dementia subtypes, the SMR for accidental death was higher in both Alzheimer’s disease (1.72, 95% CI 1.36–2.14) and vascular dementia (2.14, 95% CI 1.27–3.38). Additionally, the SMR for accidental death showed an increasing tendency as the CDR score increased (mild 1.80, 95% CI 1.32–2.42, moderate 1.86, 95% CI 1.07–3.03, severe 3.32, 95% CI 1.08–7.76). Unemployment increased the risks of both suicide (3.71, 95% CI 1.54–8.95) and accidental death (2.09, 95% CI 1.20–3.63).
Among people with cognitive impairment, the risk of death by suicide did not increase, whereas that of accidental death increased significantly. Preventive strategies for premature mortality in those with cognitive impairment should be implemented from the early stages and should include careful evaluation of the individual risk factors for each type of death.
Cognitive impairment is prevalent in late life and may impact on mortality of the elderly. The World Health Organization (WHO) estimates that the number of people over the age of 60 will be around 2 billion in 2050, while the number of dementia patients is expected to rise rapidly along with the aging population . Current data suggest that the prevalence of age-adjusted dementia in 65-year-olds is over 5% , and their mortality is 3.3–6.0 times higher than that of the general population .
To our best knowledge, this is the first cohort study on mortality according to suicide and accidental death that considers the characteristics of each cause of death in patients with cognitive impairment. It is also noteworthy that by separately performing analysis for mortality of the MCI group, we were able to better understand the characteristics of suicide and accidental death in early or milder forms of cognitive impairment. Along with follow-up data for a decade related to causes of death, our findings would contribute toward broadening knowledge of the underlying determinants of suicide and accidental death in patients with cognitive impairment.
The risk of death by suicide did not increase significantly among patients with cognitive impairment. However, the risk of accidental death was higher, especially in older patients and those with severe forms of cognitive impairment. Improved awareness and understanding of patients’ mortality are needed at the onset of cognitive evaluation in order to develop better risk-management strategies.