The association of Red cell distribution width and in-hospital mortality in older adults admitted to the emergency department
Kim et al. Scandinavian Journal of Trauma, Resuscitation
and Emergency Medicine
The association of Red cell distribution width and in-hospital mortality in older adults admitted to the emergency department
Soo Hyun Kim
Jeong Hoon Yeon
Kyu Nam Park
Sang Hoon Oh
Seung Pill Choi
Young Min Kim
Han Joon Kim
Chun Song Youn
Background: The objective of the study was to test the hypothesis that elevated red cell distribution width (RDW) at admission increases the risk of mortality in older patients admitted to the emergency department (ED). Methods: We performed a retrospective analysis of patients admitted to the ED between May 2013 and October 2013. We included patients who were older than 65 years who visited the ED with any medical problems. Baseline RDW values were measured at the time of admission to the ED. The primary outcome was all-cause in-hospital mortality. Multivariate logistic analysis was performed. Results: A total of 1,990 patients were finally included in this study. The mean age was 75 years (SD 7), and 936 (47 %) subjects were male. The in-hospital mortality rate was 3.76 % (74 patients). RDW values higher in non-survivors than in survivors (15.9 ± 2.5 vs. 13.8 ± 1.7, p < 0.001). Multivariate logistic analysis showed that RDW was associated with all-cause in-hospital mortality after adjusting for other confounding factors. Discussion: RDW value at admission is an independent predictor of all-cause in-hospital mortality among patients older than 65 years. After adjustment for multiple confounders, the all-cause in-hospital mortality rate increased by 21.8% for each 1% increase in RDW. Conclusion: These results show that RDW at admission is associated with in-hospital mortality among patients older than 65. Thus, RDW at admission may represent a surrogate marker of disease severity. We caution against using these findings to aid clinical decision-making process until they are externally validated.
Mortality; Older adults; Erythrocyte indices
Background
The proportion of elderly individuals in the population is
increasing, and older people visit the emergency department
(ED) more frequently than younger adults [
1–4
]. Older
patients often present with atypical signs and symptoms and
have multiple comorbidities that complicate accurate
diagnosis and treatment [5]. Furthermore, these patients have a
higher level of acuity, higher risk for hospitalization and
higher intensive care unit (ICU) admission rate [
6–9
].
However, there are few studies measuring the association
between the risk factors and in-hospital mortality in older
patients admitted to the ED.
Red cell distribution width (RDW) is a quantitative
measure of variability in the size of circulating
erythrocytes and is routinely reported to physicians in clinical
practice as part of the automated complete blood count
(CBC). RDW is used as an ancillary test to help diagnose
different types of anemia. Recent studies have shown that
higher RDW is associated with increased mortality risk in
different clinical settings such as clinically significant
cardiovascular disease, stroke, septic shock, bacteremia
and community-acquired pneumonia [
10–15
]. Although
the exact mechanisms that underlie the association
between RDW and mortality are unknown, high RDW
may have an association with the presence of an ongoing
disease process, such as inflammation, tissue
hypoperfusion, oxidative stress, or renal failure [16]. RDW is known
to be a strong predictor of mortality in the general
population of middle-aged and older adults [
16, 17
] and is also
considered an age-associated prognostic biomarker in
adults aged 45 and older [17]. However, the prognostic
value of RDW in older patients admitted to the ED has
rarely been investigated. In addition, older adults admitted
to the ED are likely to have multiple comorbidities.
We tested the hypothesis that elevated RDW at
admission increases the risk of mortality in older patients
admitted to the ED. We assessed the association between RDW
at admission and in-hospital mortality in older patients
admitted to the ED.
Methods
Study design
This was a retrospective, observational study of a consecutive
cohort admitted to a large urban ED in Seoul, Korea. Our
Institutional Review Board approved this study, and waiver
of consent was allowed because of its retrospective nature.
Study setting and population
This study was conducted in the Department of Emergency
Medicine of the Seoul St. Mary’s Hospital, a 1,320-bed
tertiary teaching hospital. Our ED serves an annual census of
approximately 60,000 patients. The emergency physician
provides initial treatment to all adult emergency patients.
We included patients older than 65 years who visited the
ED with any medical problems between May 2013 and
October 2013. Patients were excluded if they had a
traumarelated injury; had a hematologic disease such as leukemia,
myelodysplastic syndromes, myeloproliferative disease,
myelofibrosis or agranulocytosis; were (...truncated)