Retrospective one-million-subject fixed-cohort survey of utilization of emergency departments due to traumatic causes in Taiwan, 2001–2010
Yang et al. World Journal of Emergency Surgery
Retrospective one-million-subject fixed- cohort survey of utilization of emergency departments due to traumatic causes in Taiwan, 2001-2010
Nan-Ping Yang 0 1 2 4
Dinh-Van Phan 1 7 8
Yi-Hui Lee 6
Jin-Chyr Hsu 5
Ren-Hao Pan 7 8
Chien-Lung Chan 7 8
Nien-Tzu Chang 1 6 10
Dachen Chu 0 2 3 9
0 Institute of Public Health and Community Medicine Research Center, National Yang-Ming University , Taipei , Taiwan
1 Equal contributors
2 Faculty of Medicine, School of Medicine, National Yang-Ming University , Taipei , Taiwan
3 Department of Health Care Management, National Taipei University of Nursing and Health Sciences , Taipei , Taiwan
4 Department of Surgery & Orthopedics, Keelung Hospital, Ministry of Health & Welfare , Keelung , Taiwan
5 Department of Medicine, Taipei Hospital, Ministry of Health & Welfare , Taipei , Taiwan
6 Department of Nursing, School of Nursing, College of Medicine, Chang-Gang University , Taoyuan , Taiwan
7 Innovation Center for Big Data and Digital Convergence, Yuan Ze University , Taoyuan , Taiwan
8 Department of Information Management, Yuan Ze University , Taoyuan , Taiwan
9 Department of Neurosurgery, Taipei City Hospital , Taipei , Taiwan
10 School of Nursing, College of Medicine, National Taiwan University , Taipei , Taiwan
Background: Epidemiological study was needed to evaluate trends in emergency department (ED) utilization that could be taken into account when making policy decisions regarding the delivery and distribution of medical resources. Methods: A retrospective fixed-cohort study of emergency medical utilization from 2001 to 2010 was performed based on one-million people sampled in 2010 in Taiwan. Focusing on traumatic cases, the annual incidences in various groups split according to sex and age were calculated, and further information regarding location of trauma and type of trauma was obtained. Results: In 2010, significantly greater proportions of male and younger subjects were visitors to EDs with a traumatic injury. During 2001-2010, the number of both traumatic cases and non-traumatic cases presenting at EDs significantly increased (average annual percentage change, AAPC 4.7 and 3.6, respectively) and a significantly greater direct medical cost associated with traumatic cases than non-traumatic cases was noted. Focusing on traumatic cases, most of these cases were directed to highest-level hospitals, accounting for 73.5-78.8 % of all traumatic cases, with a significant AAPC of 5.6. The traumatic ED visit annual incidence in males was 58.63 in 2001, which significantly increased to 69.35 per 1000 persons in 2010 (AAPC 1.5); and in females was 38.96 in 2001, which significantly increased to 50.73 per 1000 persons in 2010 (AAPC 2.5). Most of the traumatic cases treated in EDs were minor injuries, such as contusion with the skin intact, open wound of the upper limbs, open wound of the head, neck, or trunk, and other superficial injury (accounting for about 60 % of all cases). The traumatic categories of sprains/strains of joints and adjacent muscles, fractures of upper limbs, fractures of lower limbs, and fractures of the spine/trunk required greater medical resources and significantly positive AAPC values (4.3, 4.0, 4.5 and 6.8, respectively). Conclusions: Increased ED utilization due to traumatic causes, as assessed by the annual number of cases and incidence, average direct medical cost and highest-level hospital utilization, was observed from 2001 to 2010. Orthopedic-related injuries, including soft tissue trauma of extremities and various fractures, were the categories with the greatest increase in incidence.
Emergency department; Trauma; Utilization
Globally, injury is a major cause of death and disability.
The burden of injury is greatest in developing countries,
and trauma registries are known to be integral in the
monitoring and improvement of trauma care [
remains great international variability in terms of patient
mix, process of care, and performance of different
prehospital trauma care systems [
]. To date, the
classification, measurement and improvement of data quality in
trauma registries have been inconsistent [
]. There is no
doubt that injury is a large issue for the health care
system, and in particular for emergency management units.
Usually, patients suffering a traumatic injury and other
acute diseases constitute the majority of ambulance
transports, and adult patients aged 15–60 years are the
principal users of Emergency Medical Services (EMSs)
]. Furthermore, triage, inter-hospital transfer processes
and protocols for inter-hospital transfer are also central
to trauma systems [
]. From the viewpoints of public
health and health policy, epidemiological study is needed
in order to evaluate trends in health care utilization,
which could inform policy decision-making for the
redistribution of medical resources, especially in
Data source, security, and quality control
Taiwan launched a single-payer National Health Insurance
(NHI) program on March 1, 1995. As of 2014, 99.9 % of
Taiwan’s population was enrolled [
]. Foreigners in Taiwan
are also eligible for this program. The database of this
program contains registration files and original claim data for
reimbursement. Large computerized databases derived
from this system by the National Health Insurance
Administration (the former Bureau of National Health
Insurance, BNHI), Ministry of Health and Welfare
(the former Department of Health, DOH), Taiwan and
maintained by the National Health Research Institutes
(NHRI), Taiwan, are provided to scientists in Taiwan
for research purposes. Only citizens of the Republic
of China who fulfill the requirements of conducting
research projects are eligible to apply for the National
Health Insurance Research Database (NHIRD). The
NHIRD includes nationwide population-based data with
good quality control and representation and is provided to
scientists in Taiwan for research purposes [
Ethics approval, and consent for participation or publication
The study design was a retrospective health data analytic
study. The protocol was evaluated and approved by the
Institutional Review Board (IRB) of Taipei Hospital,
Ministry of Health & Welfare, Taiwan, which has been
certificated by the Ministry of Health and Welfare,
Taiwan (IRB Approval Number: TH-IRB-0015-0003).
The information related to all subjects is encrypted
using a double scrambling protocol for research purposes
to protect the privacy of patients. Theoretically, it is
impossible to query the data alone to identify individuals at
any level using this database. No any individual informed
consent of all the insured is requested. All researchers
who wish to use the NHIRD are required to sign a written
agreement declaring that they have no intention of
attempting to obtain information that could potentially
violate the privacy of patients or care providers. The use
of NHIRD is limited to research purposes only. Applicants
must follow the Computer-Processed Personal Data
Protection Law and related regulations of National Health
Insurance Administration and NHRI, and an agreement
must be signed by the applicant and his/her supervisor
upon application submission.
The application of the present study was reviewed by
the NHI Administration, who gave their agreement to
the planned analysis of the NHIRD and released the
data. (Data approval Number: NHIRD-104-183).
Source and definition of study population
In this retrospective fixed-cohort study, the records of
1 million people in the NHIRD sampled in 2010 were
used to perform an epidemiological and descriptive
study of emergency medical utilization in Taiwan from
2001 to 2010. This specific longitudinal health
insurance dataset (LHID) is the latest cohort data in Taiwan
that was named LHID2010 (see Fig. 1) [
used as the study population in the present study,
contains the entire original claim data of 1,000,000
beneficiaries enrolled in year 2010 randomly sampled from
the year 2010 Registry for Beneficiaries (ID) of the
NHIRD, where registration data of everyone who was a
beneficiary of the National Health Insurance program
during the period of Jan. 1st 2010 to Dec. 31 2010 were
drawn for random sampling. There are approximately
27.38 million individuals in this registry. All the
registration and claim data of these 1,000,000 individuals
collected by the National Health Insurance program
constitute the LHID2010. There was no significant
difference in the gender distribution (p-value = 0.796) between
the patients in the LHID2010 and the original NHIRD [
The entire medical claim data of the patients enrolled
in LHID2010 was collected in the year 2010 and during
the period of 2001–2009 retrospectively. All incident ED
visits of the 1,000,000 studied subjects in each calendar
year were evaluated. The causes of ED visits were
divided into 2 groups: traumatic (ICD-9-CM diagnostic
codes ranging from 800.X to 959.X) and non-traumatic.
Traumatic cases were defined as subjects who visited an
ED due to a trauma event once or more in 1 year, while
the non-traumatic cases were defined as subjects who
visited an ED for reasons entirely due to a non-traumatic
event. Furthermore, each ED visit of the subjects was
analyzed to assess the number of annual ED visits and the
direct medical cost per ED case. Focusing on traumatic ED
cases, the distribution of hospital level, annual incidence
by gender, annual incidence by age strata, and detailed
information regarding traumatic location/type (classified
into 20 categories) [
] were studied.
Descriptive statistics are represented by numbers of
cases, percentages, and means with standard deviation
(SD). The chi-square test or independent t-test was
used to analyze significant differences between groups
for categorical or continuous variables, respectively.
The average annual percentage change (AAPC) and
its 95 % confidence interval (CI) was calculated using
the Join-point Regression Program Ver.220.127.116.11 in order
to test for time trends. 95 % CI of cumulative
incidence (ci) cab be calculated as the followed formula:
ci +/− 1.96√ci(1-ci)/N. All analyses of data were
conducted using the Hadoop big data distributed
computing environment and the Impala massive parallel
processing (MPP) SQL query engine (Cloudera
Corporation), and statistical calculations were performed
using the Statistical Package for Social Sciences for
Windows (SPSS Ver.22.0).
Of the enrolled 1 million people sampled in 2010,
176,126 subjects visited an ED, who were classified into
59,900 traumatic subjects (34 %) and 116,226
nontraumatic subjects (66 %). Significantly greater
proportions of male subjects (57 %) and younger patients
(64 %) presented as traumatic ED cases (see Table 1).
All ED visits of the subjects were analyzed as
individual cases, and the annual number of ED visits, average
direct ED medical cost per case, and time trends were
evaluated, as shown in Table 2. During 2001–2010 in
Taiwan, the numbers of both traumatic cases and
nontraumatic cases sent to EDs significantly increased
(average annual increase ratio 4.7 % (95 % CI: 3.2–6.2 %) and
3.6 % (95 % CI: 1.0–6.4 %), respectively). Although fewer
traumatic cases were seen in EDs than non-traumatic
cases, the direct medical cost of traumatic cases was
significantly greater than that of non-traumatic cases, and a
significant increasing trend of the direct medical cost
was observed for both types of case. Focusing on
traumatic cases, most (i.e., 73.5–78.8 % of all traumatic
cases) were taken to highest-level hospitals, this
incidence exhibiting a significant increasing annual trend of
5.6 % during 2001–2010 in Taiwan.
Furthermore, still focusing on traumatic cases, the
annual ED visit incidence and the annual trend were
analyzed by gender and age. The point estimation of
incidence was calculated by the number of subjects
visiting ED due to traumatic causes divided by the
numbers of various gender and age stratums among
the one million study population in each calendar
year. Because the study population of 1,000,000 subjects
was randomly sampled in 2010 whose information could
not be traced back to their original NHIRD, point
estimates of cumulative incidences were calculated and their
95 % CIs could be predicted only in 2010. Even though
the same fixed one-million subjects were studied during
2001–2009, all the 95 % CIs of point estimates of
incidence were not projected accounting for actually dynamic
total population rather than an assumedly fixed total
population in Taiwan for the past 10 years. As shown in
Table 3, the annual incidence of traumatic ED visitors in
male subjects was 58.63 per 1000 persons, significantly
increasing to 69.35 (95 % CI: 68.85–69.85) per 1000 persons
from 2001 to 2010, with an average annual change of
1.5 % (95 % CI: 0.1–2.8 %); that in the female subjects was
38.96 per 1000 persons, significantly increasing to 50.73
(95 % CI: 50.30–51.16) per 1000 persons from 2001 to
2010, with an average annual change of 2.5 % (95 % CI:
1.3–3.7 %). Analyzing the subjects by age, significant
increasing trends in the annual incidence of traumatic ED
visitors were noted in subjects aged 29 years or under and
ones aged 60 years or order. However, as illustrated in
Fig. 2, a dramatically increasing linear trend of 43.61/1000
to 70.16/1000 during 2001–2010 was noted in the subject
population aged 60 years or older, with an AAPC of 5.7
(95 % CI: 4.7–6.8), which was greater than that in other
age strata groups.
Based on the ICD-9-CM diagnostic codes, the trauma
locations of the traumatic cases in the present study
were classified into 20 categories. Table 4 shows that
most of the traumatic patients in EDs were treated for
minor injuries, such as contusion with the skin intact,
open wound of upper limb, open wound of the head,
neck, or trunk, and other superficial injury (accounting
for about 60 % of all cases, ranging from 58.5 to 63.3 %).
Besides the above-listed and some unspecified injuries,
the traumatic categories of sprains/strains of joints and
adjacent muscles, fractures of upper limbs, fractures of
lower limbs, and fractures of the spine/trunk required
greater medical resources and significantly positive
AAPC values (4.3, 4.0, 4.5 and 6.8, respectively).
aLHID2010: longitudinal health insurance dataset randomly selected in 2010
p value of χ2 test
Currency: USD: NTD = 1: 32
aAAPC average annual percentage change; the AAPC was significantly different from zero at alpha = 0.05
b95 % CI 95 % confidence interval
In the US, publicly-available ED visit data from the
National Hospital Ambulatory Medical Care Survey
(NHAMCS) from 1997 through 2007 were assessed
using codes from the International Classification of
Diseases, Ninth Revision (ICD-9). ED visit rates
increased from 352.8 to 390.5 per 1000 persons during
that time (P = .001 for trend), and adults with Medicaid
cover accounted for most of the increase in ED visits; in
addition, the visit rate increased from 693.9 to 947.2 visits
per 1000 enrollees (p = 0.001 for trend) between 1999 and
]. According to NHAMCS data from 1997 to
2009, the overall adjusted probability of an ED visit being
treatable in a primary care setting increased by 0.19 %
(95 % CI = 0.10 to 0.28) per year. This probability
increased at a rate of 0.52 % per year for Medicare patient
visits (95 % CI = 0.38 % to 0.65 %), more than double that
for Medicaid patient visits (0.25 % per year, 95 % CI =
0.13 % to 0.37 %). In contrast, there was no significant
change from 1997 to 2009 in the average probability of an
ED visit being treatable in a primary care setting in
privately-insured patients (0.05 % per year, 95 % CI =
−0.07 to 0.16) or uninsured individuals (0.00 % per year,
95 % CI = −0.12 to 0.13) [
]. In Taiwan, the ED visit rate,
including traumatic and non-traumatic cases, was
approximately 190 visits per 1000 persons in 2001, which
increased significantly to 270 visits per 1000 persons in 2010
based on one-million sampled patients who were insured
under the official Taiwan health insurance system.
Therefore, a greater increase in the ED visit rate as measured by
the AAPC, and in particular in the ED visit rate for cases
due to traumatic causes, was observed in Taiwan, an Asian
In the US, older adults (aged 75 and over),
nonHispanic black persons, less wealthy people, and those
with Medicaid coverage were more likely to have made
at least one ED visit within a 12-month period than
other subjects. Persons with Medicaid coverage were
more likely to have made multiple visits to an ED within
a 12-month period than those with private insurance
*Incidence (Inc.): cumulative incidence, 1/1000
95 % CI of Inc. in 2010
and the uninsured [
]. Based on data from the USA
National Health Interview Survey in 2012, 18 % of
children aged 0–17 years visited the ED, and children with
Medicaid coverage were more likely than uninsured
children and those with private coverage to have visited the
ED at least once in the past year [
]. A recent
systematic review concluded that in most healthcare systems,
frequent ED users were more likely to be older, female,
and have a mental health diagnosis, and previous
hospitalizations and high primary care use were associated
with future frequent ED use [
]. The main finding of
the present study was that female subjects and the
elderly (aged 65 years or more) exhibited a greater
increase in the incidence of ED visits for traumatic
reasons in Taiwan.
Overcrowding of EDs is an important issue, and in
order to design strategies aimed at avoiding
overcrowding, mathematical models used to predict ED patient
volume are considered essential. Most of the models
used to predict patient volume are linear regression
models, including Poisson regression models or time
series models that can include calendar- or
climaterelated variables. These models explain 31–75 % of the
patient-volume variability [
]. A significantly
increased rate of ED utilization was found in the present
study, especially with regards to traumatic cases, of
which cases of soft tissue trauma of extremities and
various fractures were the categories that exhibited the
greatest increasing tendencies. This information is useful
to inform Taiwan’s health authorities with regards to the
delivery and distribution of medical resources.
In Singapore, a statistical report showed that 40.7 % of
ambulance arrivals were attributable to trauma, versus
27.3 % of walk-in arrivals. The majority of trauma cases
brought in by ambulance was because of road traffic
accidents, followed by accidents in the home [
]. In India,
traffic crashes and consequent injuries represent a
growing public health concern. Open wounds and superficial
injuries to the head (69.3 %), upper extremities (27 %)
and lower extremities (24 %) were found to be the most
common injuries [
]. Based on data from the
statewide trauma registry in Queensland, Australia, from
2006 to 2010, moped/scooter riders sustained a greater
percentage of head/neck (+8.6 %), facial (+3.0 %) and
abdominal injuries (+2.3 %), whereas motorcycle riders
sustained a greater percentage of upper extremity
(+4.0 %), thoracic (+3.9 %), spinal (+3.6 %) and lower
extremity injuries (+2.6 %) [
]. In Taiwan, the incidence
of traffic accident-related hospitalization was between
9.17 and 11.54 %, and in all inpatients admitted due to
road traffic accidents, the orthopedic fractures of (1)
fracture of upper limb, (2) fracture of lower limb, and
(3) fracture of spine/trunk were the most common
injuries, accounting for 29.36 % of all injuries [
traffic accidents involving motorized two-wheeled vehicle
(MTV) riders often result in severe morbidity and
mortality. Many studies have focused on this specific issue
]. In the present study, which focused on
traumatic injuries, most traumatic cases presenting at EDs
had sustained superficial or open-wound injuries; however,
the traumatic categories of sprains/strains of joints and
adjacent muscles, fractures of upper limbs, fractures of
lower limbs, and fractures of the spine/trunk exhibited
significant annual increases in incidence. Most traumatic
ED cases in the present study were sent to highest-level
hospitals, which is contrary to another study performed in
Taiwan showing the use of the ED service in the nearest
community hospital to be more acceptable in an
emergency situation than medical center treatment for dying
cancer patients . More detailed evaluation is needed in
future studies to examine the causes of accidents and the
subsequent morbidity or mortality.
Some limitations were still persisted in the present
study. In Taiwan, no researchers can approach all the
NHI beneficiaries’ inpatient and ambulatory medical
records. A longitudinal health dataset of one million fixed
cohort populations, including their inpatient and
ambulatory medical records, was the most popular research
databank. However, more detailed personal
information such as occupation, education level, living area,
or healthy habitus were absent. Up to now, there
were three isolated longitudinal datasets containing
LHID2000, LHID2005 and LHID2010 that can
provide only point estimates for epidemiological studies
due to lack of available data of whole Taiwan’s
population in each calendar year. In another way, during
the study period of 2001–2010, 10 separated
crosssectional surveys in each calendar year might be
performed based on the truly dynamic total population
but only 0.2 % of the ambulatory care records
extracted by systematic sampling method have been
allowed to be released to Taiwanese researchers [
Finally, the latest longitudinal health dataset (LHID2010) in
Taiwan was chosen to perform a descriptive
epidemiological analysis that was designed as a retrospective
Focusing on traumatic visits of patients to EDs,
increased ED utilization was observed between 2001
and 2010 in Taiwan, as evidenced by the increases in
the annual number of cases, annual incidence assessed by
gender and age, average direct medical cost, and
highestlevel hospital utilization. Of the 20 categories into which
all traumatic causes were divided, orthopedic-related
injuries, including soft tissue trauma of extremities and
various fractures, were the categories in which the greatest
increases in incidence were observed. Greater numbers of
surgical and orthopedic physicians may be needed in EDs,
especially in the highest-level hospitals in Taiwan,
This study was partially supported by MOST-102-2221-E-155-027-MY3 &
MOST-104-2218-E-155-004. The authors would still like to thank Keelung
Hospital and the Ministry of Health& Welfare for supporting the study.
Availability of data and supporting materials
All relevant raw data and databases of NHIRD in the present study could not
be shared because all researchers are required to sign a written agreement
declaring that the NHIRD and its data subsets are prohibited to be released.
The study was designed by NPY, CLC and DC; data were gathered and
analyzed by NPY, DVP, NTC and RHP; the initial draft of the manuscript was
written by NPY, DVP and NTC; the accuracy of the data and analyses was
assured by YHL, JCH and DC. All authors participated in the preparation of the
manuscript and approved the final version. All authors have read and approved
the final manuscript. NPY, DVP and NTC contributed equally to this work.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
The Institutional Review Board (IRB) of Taipei Hospital, Ministry of Health &
Welfare, Taiwan approved the present study (Approval Number:
TH-IRB-00150003) and informed consent was waived.
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