Background
The nonagenarian population continues to grow globally with the aging of the population [
1]. In developing countries like China, the percentage of people aged 90 and above had reached 0.19% in 2015 with the increase of the average life expectancy from 72.95 years in 2005 to 76.34 years in 2015 [
2]. However, these populations are generally excluded from most clinical trials. Due to this lack of evidence in the nonagenarian population, general clinical practice for this population has gained considerable attention during recent years, with clinical trials including nonagenarians mainly focused on the fields of surgery [
3‐
7], chemotherapy [
8], interventional operation [
9‐
12] and trauma [
13], in the departments of orthopedics, vascular surgery, general surgery, and oncology, rather than a department of internal medicine. In real-world clinical practice, about one-third of the patients over 90 years old have been admitted to an internal medicine department [
14]. Moreover, clinical trials studying nonagenarian patients admitted for acute infection, one of the most common causes of hospitalization in these patients [
15,
16], have been rarely reported. The clinical characteristics of the nonagenarian patients admitted for acute infection, and more importantly, the predictors of in-hospital mortality in these patients, remain to be determined. Therefore, we performed a cohort study of the nonagenarian patients admitted to the internal medicine department to explore the clinical characteristics of these patients and identify potential determinants of their clinical outcomes.
Discussion
In this retrospective cohort study, we found that the in-hospital mortality for nonagenarian patients admitted for acute infection was quite high (17.2%). Moreover, functional impairment as well as serum albumin were independent predictors of in-hospital mortality in our cohort of nonagenarian patients hospitalized for acute infectious diseases. These findings suggest that it is very necessary to stratify the patients based on BI score and serum albumin. Additionally, maintaining good functional status and supplementation with albumin may be important for improving clinical outcomes in nonagenarian patients hospitalized for acute infectious diseases.
Previous studies confirmed that, independent of the type of disease diagnosed on admission, the in-hospital mortality rate among nonagenarian patients is much higher than that among patients 65–90 years of age [
23]. Similarly, the in-hospital mortality rate was 17.2% in our study, with one in six patients aged 90 years or older suffering from acute infectious diseases died in our study. This is consistent with previous studies in which the in-hospital mortality for the nonagenarian population ranged from 13.3–22.8% in internal medicine departments and geriatric acute units [
15,
16,
23‐
25]. With regard to the sites of infection, a previous report in Taiwan showed that pneumonia and urinary tract infection were the two major infectious diseases on admission for nonagenarians [
26]. Similarly, respiratory tract infection was the main cause of acute infection in our cohort, highlighting the importance of the prevention of respiratory tract infection in these patients. Moreover, we found that the prevalence of atrial fibrillation and malignant diseases differed significantly between those who discharged and those died during the hospitalization. The presence of malignant diseases results in a more than 2-fold increase in the likelihood of in-hospital death in multivariate analysis. A previous research in Israel also found that atrial fibrillation and malignant diseases were the main predictors of in-hospital mortality among nonagenarians [
15], which is similar to our findings. Previous epidemiological data from China showed that the prevalence of atrial fibrillation in the general population aged ≥60 years was 1.83% in China [
27], which further confirmed the increased prevalence of atrial fibrillation with aging. Notably, although the proportion of patients with multimorbidity in our cohort was high (144/162, 88.9%), the proportions of patients with multimorbidity did not differ statistically between two groups. This is different from previous findings, which showed that multimorbidity was associated with a higher mortality rate in a population-based study of nonagenarians [
28,
29] and in hospitalized nonagenarians [
16,
24]. However, a previous study showed that geriatric conditions rather than the multimorbidity predicted the risk of mortality in an octogenarian population [
30]. These inconsistencies may be explained by the different management statuses of the diseases in the octogenarian patients in different studies. Nonagenarian patients may have good prognosis if their diseases are well treated, despite the presence of multimorbidity.
We found that functional impairment as well as serum albumin were independent predictors of in-hospital mortality in our cohort of nonagenarian patients hospitalized for acute infectious diseases. For every 5-point increase in the BI score, the likelihood of in-hospital death decreased by 18%. For every 1-unit increase in serum albumin, the odds of death decreased by 14%. ADL is one of the most important factors that reflect the health status of an individual. Poor ADL at discharge has been associated with increased risk of 1-year mortality for older patients undergoing percutaneous coronary intervention [
31]. Serum albumin plays a vital physiologic role in health maintenance for many organs. Hypoalbuminemia had been historically linked to patients’ nutritional status, and recently, it has been suggested that hypoalbuminemia is an inflammatory marker rather than an index of malnutrition in sarcoidosis patients [
32]. Hypoalbuminemia also increases the short-term mortality for patients attending the emergency department, and the long-term mortality is also increased in older patients with hypoalbuminemia [
33,
34]. Taken together, our results also confirmed the clinical prognostic properties of ADL and serum albumin for mortality in population-based or hospitalized nonagenarians [
16,
17,
25,
28,
35,
36]. A previous study showed that for nonagenarian patients, due to acute medical illnesses, hypoalbuminemia and functional loss at the time of discharge are factors associated with 1-year mortality [
25]. In the Rugao longevity cohort in China, both serum albumin and ADL were effective predictors of all-cause mortality in long-lived individuals aged 95 years or older, and the combination of albumin and ADL was recommended as an inexpensive, easy-to-use screening method for risk stratification of nonagenarian patients [
35]. Stratification of patients on admission, maintenance of good functional status, and supplementation with albumin may be important for improving clinical outcomes in nonagenarian patients hospitalized for acute infectious diseases. Prospective clinical trials are needed to confirm it.
There are limitations in this study. First, this was a retrospective single-center study. The results of our study should be confirmed in prospective trials. Second, other types of comprehensive geriatric assessments besides functional status were not performed in our study, such as delirium assessment, cognitive assessment, and visual or hearing impairment assessment. The association between these factors and in-hospital mortality in nonagenarian patients hospitalized for acute infectious disease remains to be determined. Finally, the sample size of the cohort was relatively small, that makes the extension and generalization of the results difficult. The predictive efficacies of functional status and hypoalbuminemia for mortality risk after discharge should be evaluated in the future.
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