Introduction
Life expectancy is rising, and older orthopaedic trauma patients presenting to the emergency department (ED) are becoming a bigger part of the workload for orthopaedic surgeons [
1]. Older patients often present with complex multidisciplinary medical problems, cognitive impairment and a higher level urgency, which complicates their evaluation and management [
1]. Older orthogeriatric patients are also at risk for negative medical outcomes, such as functional decline and mortality [
2]. It is important to identify high-risk patients in an early stage, in order to implement geriatric interventions to improve patient outcomes [
3]. Identification of high-risk patients may also provide information for better informed treatment decisions and surgical management.
Patients aged 85 years or above constitute the fastest growing age group and are at even higher risk for postoperative complications and death than the general geriatric population [
4‐
7]. These geriatric fracture patients are a distinct age group with considerable risk of negative medical outcomes. Many studies have been done that include these older patients, especially hip fracture patients. These studies have shown that age, male gender and comorbidity are important predictors of mortality, but few have specifically targeted the age group of patients aged 85 or above [
6,
8]. Most studies focus on hip fractures and not the general population of geriatric orthopaedic trauma patients [
8]. There is need for more research targeting this age group to identify risk factors for negative medical outcomes, which is why this study will exclusively target patients 85 years or above. The threshold of 85 years or above was chosen based on previous investigations [
7,
9]
Additionally, this study will target the general geriatric population of fracture patients (i.e. any fracture regardless of treatment) as well as hip fracture patients undergoing surgery.
The primary aim of this study was to identify independent risk factors for 30-day mortality in patients 85 years or above admitted from the emergency department with any fracture. The secondary aim of this study was to identify independent risk factors for 30-day mortality in hip fracture patients aged 85 years or above undergoing surgery.
Methods.
Study design and patient selection
The study period for this retrospective cohort study was 1-1-2012 until 31-12-2016. All patients 85 years or older presenting with a fracture at the ED who were admitted to the hospital were eligible for inclusion. Data collection was done by consulting the electronic patient files. This retrospective cohort study was conducted in a level 2 trauma center at St. Antonius Hospital, Utrecht, The Netherlands. The study was approved by the local institutional review board of St. Antonius Hospital and was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. The Dutch Medical Research Involving Human Subjects act (WMO) did not apply to this study.
Identification of eligible patients was done using the diagnostic codes (DBC) for the most common fractures: wrist, fore arm, upper arm, shoulder, neck, vertebrate, pelvis, hip (proximal femur), distal femur, knee, lower leg and ankle. Patients were excluded if 1; primary survey was not performed at St Antonius hospital 2; if patients were discharged to another hospital or 3; if patients were admitted directly to intensive care unit 4; primary treatment was given at the ED, but the patient was not admitted 5; the patient had a pathological fracture or 6; the patient had a periprosthetic fracture. If a patient was admitted multiple times in the study period, only the first admittance was used.
Measurements
A number of variables were collected based on literature and availability [
6,
8,
10,
11]. The following pre-operative baseline variables were collected upon admission to the ED: age, sex, Body Mass Index/ Quetelet index (BMI), living situation prior to admission (at home, at home with home care, institutional care facility, other), whether or not the patient was living with a partner, number of different comorbidities (as mentioned in admission form), number of different medications, whether patients had experienced a previous episode of delirium, cognitive impairment (as mentioned in the admittance form, either declined or not declined), use of oral anticoagulants (yes/no), hemoglobin- (mmol/L), creatinine-(µmol/L), C-reactive protein (mg/L) levels. For patients undergoing surgery (regardless of fracture type) the following variables were collected: type of surgery (if any), type of anesthesia (general or regional, only applicable for patients undergoing surgery) and American Society of Anesthesiologists (ASA) classification (1 to 5).
Outcome
The 30-day mortality was determined by consulting electronic patient files. For patients with an unknown date of death the last professional caregiver was contacted to ascertain the exact date of death.
Statistical analysis
All statistical analyses were done using IBM SPSS Statistics for Windows, Version 25.0 (IBM Corp., 2017, Armonk, NY). The level of significance (α) was set at 0.05. Differences between deceased and surviving patients were analyzed at baseline. Normally distributed continuous data were presented as mean and standard deviation (SD) and tested with an unpaired t test. Not normally distributed continuous data were presented as median and interquartile range (IQR) and tested with a Mann–Whitney U test. Distribution was determined with the Shapiro–Wilk test for normality. All categorical and dichotomous data were tested with a chi-square test.
Multivariable analysis
To reduce the number of possible predictors, candidate predictors to be included in the multivariable model were selected based on clinical relevance, availability, expert opinion and literature [
12]. No univariable predictor selection was done which is in line with current recommendations by expert in the field of prediction modelling as it introduces data driven predictor selection bias [
12,
13]. A full model approach was used, with at least 10 events per variable [
14]. Missing data in the initial cohort were analyzed for patterns using Little’s missing completely at random (MCAR) test except for ASA classification and type of anesthesia, which were missing for all patients who did not undergo surgery. Data missing completely at random (MCAR) were imputed using multiple imputation techniques (5 imputations).
Subgroup analysis
Because hip fractures are the most common indication for surgery in orthogeriatric trauma patients, a subgroup analysis was performed for all hip fracture patients undergoing surgery. Missing data for all variables including ASA classification and type of anesthesia were analyzed for patterns using Little’s MCAR test. An additional multivariable logistic regression analysis was performed to calculate the odds ratio (OR) for the selected candidate predictors in this subgroup.
Results
Baseline characteristics
In total, 810 eligible cases were identified, 83 of which met the exclusion criteria and 35 patients were admitted two times during the study period. This resulted in an included cohort of 692 patients. After 30 days a total of 86 patients (12%) had deceased. Baseline characteristics of survivors and deceased patients are summarized in Table
1.
Table 1
Baseline characteristics of 30-day mortality vs. survivors. All percentages are calculated for valid data (i.e. excluding missing data)
Age, median (IQR) | 89 (87–92) | 0 | 90.5 (87–94) | 89 (87–92) | < 0.01 |
Male sex, n (%) | 149 (22%) | 0 | 29 (34%) | 120 (20%) | < 0.01 |
BMI (kg/m2), median (IQR) | 24 (21–26) | 180 | 21 (19–24) | 24 (22–26) | < 0.01 |
Living situation, n (%) | | 27 | | | < 0.01 |
At home / at home with care | 350 (53%) | 36 | 29 (35%) | 321 (56%) | < 0.01 |
Living in institutional care facility | 306 (47%) | 36 | 54 (64%) | 252 (44%) | < 0.01 |
Living with partner, n (%) | 107 (16%) | 17 | 16 (19%) | 91 (15%) | 0.39 |
Comorbidity | | | | | |
Number of comorbidities, median (IQR) | 3 (2–5) | 62 | 4 (2–5) | 3 (2–5) | < 0.01 |
Number of different medications, median (IQR) | 6 (4–8) | 69 | 7 (5–10) | 6 (4–8) | < 0.01 |
Prior delirium, n (%) | 199 (31%) | 40 | 35 (44%) | 164 (29%) | < 0.01 |
Impaired cognitive functioning, n (%) | 278 (42%) | 29 | 47 (57%) | 231 (40%) | < 0.01 |
Use of oral anticoagulants, n (%) | 392 (62%) | 63 | 61 (78%) | 331 (60%) | < 0.01 |
Biomarkers | | | | | |
Hemoglobin (mmol/L), mean (SD) | 7.5 (1.0) | 88 | 7.2 (1.1) | 7.6 (1.0) | < 0.01 |
Creatinine (µmol/L), median (IQR) | 79 (64–100) | 195 | 95 (74–109) | 78 (63–98) | < 0.01 |
C-reactive protein (mg/L), median (IQR) | 5 (1–18) | 153 | 6 (1–31) | 5 (1–18) | 0.56 |
Type of surgery, n (%) | | 5 | | | 0.15 |
Spinal column | 2 (0%) | | 1 (1%) | 1 (0%) | |
Proximal humerus | 11 (2%) | | 3 (4%) | 8 (1%) | |
Distal humerus | 2 (0%) | | 0 (0%) | 2 (0%) | |
Hip fracture (proximal femur or collum) | 492 (72%) | | 55 (65%) | 437 (73%) | |
Distal femur | 18 (3%) | | 3 (4%) | 15 (3%) | |
Ankle | 19 (3%) | | 0 (0%) | 19 (3%) | |
Other trauma surgical procedure | 1 (0%) | | 0 (0%) | 1 (0%) | |
Conservative treatment | 142 (21%) | | 23 (27%) | 119 (20%) | |
Type of anesthesia, n (%)a | | 13 | | | 0.57 |
General | 452 (84%) | | 52 (12%) | 400 (89%) | |
Regional | 85 (16%) | | 8 (9%) | 77 (91%) | |
ASA classification, n (%)a | | 81 | | | < 0.01 |
1 | 14 (3%) | | 0 (0%) | 14 (3%) | |
2 | 217 (46%) | | 17 (30%) | 200 (48%) | |
3 | 230 (49%) | | 34 (62%) | 196 (47%) | |
4 | 8 (2%) | | 4 (7%) | 4 (1%) | |
5 | 0 (0%) | | 0 (0%) | 0 (0%) | |
Patients who died during follow-up were older at baseline than survivors. Deceased patients were more often male, and they had a lower BMI. Patients living in an institutional care facility were more likely to die during follow-up. Patients who died had more comorbidities than survivors and used more medications. A previous episode of delirium was associated with 30-day mortality, as was impaired cognitive function. The use of oral anticoagulants was higher in the deceased group, hemoglobin levels (mmol/L) were lower, and creatinine levels were higher. A higher ASA classification was associated with 30-day mortality.
Missing data and multivariable analysis
In the initial cohort, missing data were missing completely at random (Little’s MCAR test
p = 0.702). In the subgroup, all missing data, including ASA classification and type of anesthesia, were also missing completely at random (
p = 0.625). The results of the multivariable analysis are shown in Table
2. It showed that age was an independent risk factor for 30-day mortality (OR 1.11 for each year above 85 years), as was male sex (OR 2.96) and living in an institutional care facility (OR 2.31). Each 1 mmol/L decrease in hemoglobin increased the chance of mortality (OR 1.34), as did each 1-point decrease in BMI (OR 1.15). Previous episodes of delirium, the use of oral anticoagulants or surgical intervention were not independent predictors of mortality in this study.
Table 2
Multivariable analysis for all admitted patients and subgroup analysis for all hip fracture patients undergoing surgery
Age (per year above 85) | 1.11 | 1.04–1.18 | < 0.01 |
Male sex | 2.96 | 1.68–5.23 | < 0.01 |
Living in an institutional care facility | 2.31 | 1.34–3.99 | < 0.01 |
Previous episode of delirium | 1.32 | 0.76–2.30 | 0.32 |
Hemoglobin (each 1 mmol/L decrease) | 1.34 | 1.06–1.70 | 0.02 |
BMI (each point decrease) | 1.15 | 1.02–1.29 | 0.02 |
Use of oral anticoagulants | 2.22 | 0.88–5.56 | 0.09 |
Surgical intervention for any fracture | 0.60 | 0.34–1.06 | 0.08 |
Hip fracture patients undergoing surgery (n = 492) |
Age (per year above 85) | 1.14 | 1.05–1.25 | < 0.01 |
Male sex | 3.09 | 1.56–6.10 | < 0.01 |
Living in an institutional care facility | 1.94 | 0.99–3.79 | 0.05 |
Hemoglobin (each 1 mmol/L decrease) | 1.25 | 0.93–1.70 | 0.14 |
BMI (each point decrease) | 1.22 | 1.02–1.46 | 0.03 |
ASA classification (per class increase) | 1.93 | 0.97–3.83 | 0.06 |
The subgroup analysis for patients with hip fractures undergoing surgery consisted of 492 patients, of whom 55 died during follow-up (11%). The multivariable analysis for this group showed similar results for age (OR 1.14 for each year above 85 years) male sex (OR 3.09) and BMI (OR 1.22) as independent predictors of mortality. ASA classification and living in an institutional care facility were borderline significant. Hemoglobin levels at presentation at the ED were not a statistically significant independent predictor of mortality in this subgroup.
Conclusion
This study shows that all older orthogeriatric trauma patients who are admitted to the hospital with a fracture have a high risk (12%) of 30-day mortality, regardless of treatment. Several routinely collected predictors of 30-day mortality in admitted geriatric fracture patients were identified. In the population of geriatric fracture patients, independent risk factors for mortality were: increased age, male sex, living in an institutional care facility, decreased hemoglobin levels or decreased BMI. For geriatric hip fracture patients, independent risk factors were: increased age, male sex and decreased BMI. The authors advocate to regard any fracture patient aged 85 or above as a high-risk patient.
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