Our study deals with older adults ≥80 years old. We studied the risk factors of mortality within one year from blood withdrawal on admission to the acute geriatric ward. A higher percentage of men than women died, quite similarly to the findings of some other studies [16–18] and in contrast to other studies [19, 20]. Higher age was an independent risk factor of mortality. The risk of death was higher by about 5% in older subjects, although surprisingly, the mean age of the older adults, who survived was higher (93.13 ± 3.06) than that of those who died (87.96 ± 5.77). It can be explained by a higher proportion of women among the survivals (52% vs. 29%) in whom life expectancy is higher.
In our study, on-admission serum 25(OH)D levels below 50 nmol/L, were determined in 53.6% of the study population. Serum 25(OH)D is generally accepted as first choice measurement of vitamin D status, and it is used to classify vitamin D. The Endocrine Society Guidelines classify 25(OH)D levels below 50 nmol/L as deficient and levels of 75 nmol/L as sufficient, whereas the Institute of Medicine (IOM) suggested vitamin D deficiency to be indicated by 25(OH)D levels below 30 nmol/L and a level of 50 nmol/L to be sufficient [8].
Hypovitaminosis D is frequent in older subjects, ranging in occurrence from 50–90%, depending on the definition used and the setting [9]. Studies conducted in Australia revealed a higher risk of vitamin D deficiency in older people, who were hospitalized or residing in residential facilities [5].
Vitamin D is essential for bone mineralization, but a growing body of evidence points at a broader role [4, 8]. Vitamin D receptors are ubiquitous in the human body, and while the endocrine effects of vitamin D are well recognized, less appreciated are the autocrine and paracrine effects (antimicrobial and immunomodulatory) [6].
In hospitalized very old subjects, a higher comorbidity burden is associated with lower 25(OH)D serum levels [9] Vitamin D deficiency has been found to be associated with mortality, and several diseases ranging from cardiovascular disease to autoimmune diseases and liver diseases [6, 8]. However, it is unclear whether this is explained by reverse causation, and if there are specific causes of death for which vitamin D might be important [12].
Despite an upsurge in medical research, the literature on determinants of survival in geriatric inpatients is scarce. In our study, vitamin D levels of < 50 nmol/L was an independent risk factor of mortality, and increased mortality risk by 2.28. In observational study of osteoporotic women aged 75 and older, 25(OH)D levels of less than 50 nmol/L were associated with greater all-cause mortality for up to 10 years. In that study, in women with vitamin D levels < 50 nmol/L, mortality risk in the low category was almost doubled twice than the high category, and remained higher even after adjustment for smoking and comorbidities, and was highest when additionally adjusted for osteoporosis, HR = 2.1 [15]. In an epidemiological study of Australians older men, the risk of death was greater in those with vitamin D levels < 50 nmol/L than in those with a serum 25(OH)D level of 75 nmol/L or greater (adjusted HR = 1.42) [5]. In a study in critically ill patients, a longer survival was observed in vitamin D sufficient patients [21]. Also, a retrospective study by Dudenkov et al. (14] reported a statistically significant inverse relationship between serum 25(OH)D levels and mortality in 11,022 white and nonwhite community patients registered in the Rochester Epidemiology Project.
In the present study, additional factors were independent risk factors of mortality.
Hypoalbuminemia is a prognostic risk factor of mortality among older adults [10, 22]. Low levels of albumin are associated with worse recovery following acute pathologies [23]. Higher albumin levels, in our study, had a protective effect, correspondingly to other studies [22, 24]. Serum albumin plays a vital physiologic role in health maintenance for many organs. Hypoalbuminemia might be an indicator of malnutrition, which explains the bad prognosis [22, 25]. Hypoalbuminemia, in the present study, was associated with lower serum vitamin D levels, deficiencies that might eventually deteriorate to death, especially when being independent risk factors of mortality. Concomitant conditions of hypoalbuminemia and lower vitamin D levels may prompt to look for a high-risk group of geriatric patients, who could be targeted for more careful and closer follow-up and intervention for an extended time.
A higher rate of older adults with on-admission CHF, died, and the risk of mortality among them was higher by about 1.9. In other study, in hospitalized patients aged ≥ 80 years with acute myocardial infarction, on-admission left ventricular ejection fraction < 40% predicted 1-year mortality [26]. Comorbid CHF in patients aged ≥ 90 hospitalized in acute geriatric ward, was an independent risk factor of in-hospital mortality [27].
A higher proportion of older adults with high vitamin B12 levels died, and high vitamin B12 level was a significant predictor of mortality. In many studies performed on the aged, the focus is usually on detecting vitamin B12 deficiency [28]. In contrast, less is known about the meaning of high vitamin B12 levels. High vitamin B12 levels, as a predictor of increased mortality in malignancies and liver disease, have been already documented [29, 30]. In several studies, high vitamin B12 levels, in older patients suffering from acute and chronic diseases except for malignancy, were associated with higher mortality [31–37].
Older people are prescribed a greater number of medications which may be inappropriate,
fueling the cycle of comorbidity, disability, hospitalization, nursing home placement, and
mortality [38]. In the present study, a higher percentage of older adults, who consumed ≥5 drugs, died, and a higher number of drugs consumed was found to be an independent risk factor of mortality.
In our study, the risk of mortality, in subjects who consumed antipsychotics, was higher by slightly more than twice. Antipsychotic use was an independent risk factor of mortality, correspondingly to Tal’s finding found in oldest old patients within one year after discharge from acute geriatric ward [39]. Also, in some other studies antipsychotics consumption enhanced mortality [40, 41]. Antipsychotic medications are used to treat and manage symptoms of many psychiatric disorders [42]. There are several likely mechanisms by which antipsychotics may increase the risk of death. Antipsychotics may prolong the QT interval, predisposing patients to arrhythmias and sudden cardiac death. Additionally, sedation and accelerated cognitive decline, caused by antipsychotics, may increase the risk of aspiration and choking, especially in patients with dementia [43].
In our study, a higher percentage of subjects, treated with anticoagulants, died. Anticoagulant treatment increased the risk of mortality by about 2.6. Although it was shown in several studies, that anticoagulant therapy clearly outweighs the risk of heavy bleeding, even in the older adults [44–46], the clinician should probably consider treating with caution older patients with many comorbidities, including falls.
Our study has all the disadvantages of a retrospective observational study. We did not have all the details that may have been influencing mortality in the older adults within one year after on-admission blood withdrawal, because they were not found in the patients' electronic data. Consequently, the significant independent variables (age, male sex, number of drugs, on-admission CHF, low albumin, vitamin B12, vitamin D < 50, antipsychotics or anticoagulants use) comprise only part of mortality predictors. Some other unknown variables might explain the remainder.
Our study strength lies in its sample's relatively large size. Since the study focuses on mortality predictors in the ≥ 80-year adults within one year from on-admission blood withdrawal, we would like to point out that we have contributed to the medical knowledge concerning this population of older adults, whose proportion in the geriatric population is recently significantly increasing.