Risk factors for nine-year mortality of elderly patients with cognitive impairment at admission

Author(s): Hiroshi Yamamoto, Kenichi Ogawa, Yasushi Hisamatsu, Kazuo Matsuo, Hideyo Yamamoto, Tatsuya Ishitake

Background: Dementia can be a major cause of mortality and morbidity in geriatric patients. It is thus essential to assess their mental state at an early stage.
Aims: We appraised the impact on mortality and hospital outcomes using the revised simplified short-term memory recall test (STMT-R) with simultaneous collection of clinical data.
Methods: The subjects were 612 acute inpatients ≥65 years old encountered from December 2014 to September 2015. Following the collection of clinical data, the survival was subsequently measured for eight to nine years until December 2023. An STMT-R score of ≤4 was considered to indicate cognitive dysfunction. To explore the association between the risk factors and mortality in cognitive impairment subjects, the Kaplan-Meier method and Cox’s proportional hazards regression models were used to examine mortality and survival rates.
Results: The mean age of the subjects was 82.1 (±7.94) years old, and 55.9% were female. The cognitive function was classified into three categories according to severity: Incomplete Testing Group (Incomplete), Cognitive dysfunction Group (Abnormal) and Non-Cognitive dysfunction Group (Normal). A total of 325 patients (51.5%) died during follow-up. The Kaplan-Meier and the log-rank tests showed a negative prognostic effect of cognitive impairment, malnutrition, pneumonia and cancerbearing state (p<0.01). After adjusting for potential covariates, the Cox regression analysis showed that the mortality hazard is increased for “Incomplete” (hazard ratio 3.53; 95% confidence interval 2.39-5.21 p<0.0001) and “Abnormal” (hazard ratio 1.68; 95% confidence interval 1.21-2.32 p<0.01).
Conclusion: Malnutrition, hypoalbuminemia and a cancer-bearing state can significantly decrease the survival rate in patients with cognitive impairment at admission. Cognitive impairment also has an independent impact on survival rate in acutely ill geriatric patients.