Article, Neurology

Factors associated with use of emergency medical services in patients with acute stroke

a b s t r a c t

Purposes: The aim of this study was to investigate the factors associated with use of emergency medical services (EMS) in patients with acute stroke.

Methods: Prospective data on consecutive patients with acute stroke who presented to the emergency department of a university medical center from January 1, 2010, to July 31, 2011, were analyzed. Patients were excluded if they had an unknown residence, had onset of stroke at a nursing home or hospital, or were transferred from another hospital. Variables for all patients with stroke and ischemic stroke who did and did not use EMS were compared.

Results: In total, 1344 patients (60% male; mean age, 68.7 years) were included. Use of EMS (n = 409; 30.4%) was significantly associated with a higher level of education ( 3/4 6 years vs b 6 years; odds ratio [OR], 1.69; 95% confidence interval [CI], 1.25-2.29), a higher National Institutes of Health Stroke Scale score (OR, 1.08; 95% CI, 1.05-1.11), Altered consciousness (OR, 1.88; 95% CI, 1.25-2.84), and atrial fibrillation (OR, 2.43; 95% CI, 1.71- 3.44) after adjustment. For patients with ischemic stroke, use of EMS was significantly higher in cases of cardioembolism (OR, 3.04; 95% CI, 1.40-6.60) and large artery atherothrombosis (OR, 2.10; 95% CI, 1.22-3.62) than lacunar infarction.

Conclusion: Patients with stroke who have altered consciousness, a higher level of education, a higher National Institutes of Health Stroke Scale score, atrial fibrillation, and cardioembolic stroke were more likely to use EMS.

(C) 2013

  1. Introduction

In Taiwan, stroke has been the second or third leading cause of death in the past 2 decades and leads to great loss of quality-adjusted Life expectancy [1,2]. Each year, there have been more than 80 000 hospital admissions for stroke in Taiwan, and the cost of hospitali- zation for stroke is nearly US$170 million [3]. Acute ischemic stroke

? This article was supported by Grant No. 100-S1870 from National Taiwan University Hospital.

?? The authors report no conflicts of interest. The authors alone are responsible for

the content and writing of this manuscript.

* Corresponding authors. Jiann-Shing Jeng, MD, PhD, is to be contacted at Department of Neurology, and Matthew Huei-Ming Ma, MD, PhD, Department of Emergency Medicine, National Taiwan University Hospital, Taipei 100, Taiwan. Tel.:

+886 2 23123456×65338; fax: +886 2 23418395.

E-mail addresses: [email protected] (M.H.-M. Ma), [email protected] (J.-S. Jeng).

1 These authors contributed equally to the study.

(IS) accounts for most cases of stroke, and timely revascularization with thrombolytic therapy is the most effective maneuver to salvage ischemic brain tissue that is not already infarcted [4]. Intravenous thrombolytic therapy with tissue plasminogen activator has been shown to be of benefit for patients with acute IS, but it should be administered within 4.5 hours of the onset of stroke [5,6]. Despite the evidence in favor of early treatment, the frequency of tPA adminis- tration in patients with IS remains low. In Taiwan, only 1.5% of patients with IS were treated with tPA between 2006 and 2008 [7], which is lower than that reported in the United States (3.4%-5.2%) [8] and in the Swedish Stroke Register (6.0%) [9]. Among several reasons for excluding thrombolytic therapy for patients with acute IS, prehospital delay represents a significant barrier [10,11]. Some studies have reported that the use of emergency medical services (EMS) can significantly reduce prehospital delay [12,13].

The American Heart Association and American Stroke Association recommend 3 steps to decrease prehospital delay–symptom

0735-6757/$ – see front matter (C) 2013 http://dx.doi.org/10.1016/j.ajem.2013.01.019

N.-C. Chen et al. / American Journal of Emergency Medicine 31 (2013) 788791 789

recognition, calling EMS, and rapid response by EMS–and emphasize that calling EMS ought to be the first and only response to suspected symptoms of stroke [14]. Data have shown that 29% to 65% of patients with signs or symptoms of acute stroke accessed their initial medical care via local EMS [15-20]. However, according to a regional hospital study in Taiwan, only 22% of patients with acute stroke use EMS [21]. More efforts are needed to enhance the use of EMS by patients during the early presentation of an acute stroke among eligible hospitals in Taiwan. Therefore, the aim of the present study was to analyze the factors associated with use of EMS in laypersons with acute stroke at a medical center in Taiwan.

  1. Materials and methods

This prospective cohort study was based on the Stroke registry at National Taiwan University Hospital (NTUH) [22,23], which was started in 1995 to investigate the risk factors, clinical course, prognosis, and complications of patients with different types of stroke, including IS, intracerebral hemorrhage (ICH), subarachnoid hemorrhage , and Transient ischemic attack . The diagnostic criteria for stroke and TIA were in accordance with those defined by the World Health Organiza- tion [24]. Ischemic stroke was further classified based on the diagnostic criteria adopted from the Trial of Org 10172 in Acute Stroke Treatment classification system [25]. If an acute stroke or TIA was diagnosed, the patient was invited to join the registry by 1 of the 3 trained study nurses. If the patient was unconscious, the invitation was extended to the patient’s next of kin. After written informed consent was acquired, medical and other associated information about the patient was gathered prospectively using a structured recording form by interview- ing the patient and his or her relatives and by reviewing the medical record. The representativeness of the registry was previously demon- strated in a comparison with the Database of Catastrophic Illness of the National Health Insurance, which collected information on all registered patients with acute stroke for waiving copayment in Taiwan [2].

National Taiwan University Hospital is a primary and Tertiary medical center with approximately 2450 beds and an average of 110 000 emergency department (ED) visits per year. Approximately 300 000 residents of Taipei City and New Taipei City live in the catchment area of NTUH. The emergency medical technicians for the 2 cities provide EMS in the catchment area. The EMS system of both cities is a mixed 1- and 2-tier fire-based system [26]. Basic life support teams are responsible for providing EMS to most patients with stroke. The Cincinnati Prehospital Stroke Scale is used by EMTs in both cities to identify patients with stroke. Asking about the time of onset of symptoms and checking the patient’s blood glucose level by finger-stick testing are part of the standard protocol for the care of patients with suspected stroke.

We extracted data on the patients with acute stroke or TIA who presented to the ED at NTUH from January 1, 2010, to July 31, 2011. If a patient visited the ED more than once during the study period, only the first ED visit was included for analysis. Abstracted data included arrival route (EMS system, private vehicle, transfer from other hospital, transfer from outpatient clinic, or private ambulance), type of residence (own home, nursing home, other place, and unknown), site of onset of stroke (patient’s home, workplace, hospital, place except home, hospital and workplace, and unknown), symptoms of stroke, findings on physical examination in the ED, risk factors, comorbidity, years of education, Diagnostic tests.performed, and the results of diagnostic tests. The severity of stroke/TIA was scored using the National Institutes of Health Stroke Scale . Symptoms of stroke were recorded as documented according to the statement of the patient or family members and then were collapsed into 7 groups thought to be the most relevant to the lay public, as previously mentioned in another study: (1) weakness of arm, leg, or face; (2) numbness of arm, leg, or face; (3) slurred speech, aphasia, or language problems; (4) altered consciousness; (5) headache; (6) visual abnormalities; and (7) dizziness (including vertigo and problems

with balance or coordination) [27]. Patients could have more than 1 symptom category assigned; for example, a patient could have had weakness, numbness, and slurred speech.

Because the intent of this analysis was to study the lay public’s response to symptoms of stroke, patients were excluded if their residence was a medically supervised environment. Therefore, patients who were residents of nursing homes and patients who had onset of symptoms or were first evaluated at a medical facility other than a hospital ED (where the patient was an outpatient or a visitor) were excluded. In addition, patients who had an unknown site of onset or an unknown site of residence were also excluded. The study received approval from the institutional review board of NTUH.

Statistical analysis

The ?2 test, Student t test, and Wilcoxon rank sum test were used for univariate analyses of variables associated with use of EMS. Multivariate logistic analysis was used to determine the independent variables of P b .2 in the univariate analyses. Because it was only possible for patients with IS to receive thrombolytic therapy, factors associated with use of EMS among patients with IS were also searched using the previously mentioned statistical methods for univariate and multivariate analyses. A P value less than .05 was defined as statistically significant. The SAS software (version 9.2; SAS Institute Inc, Cary, NC) was used in statistical analysis.

  1. Results

In total, there were 1764 patients with acute stroke or TIA, with 1853 ED visits during the study period. Only the first ED visit of the same patient was included. Patients were excluded for the following reasons: unknown residence (n = 69), onset of stroke at a nursing home (n = 7), onset of stroke while in the hospital (n = 8), transferred from another hospital (n = 319), missing documentation of arrival route (n = 1), and unknown site of onset (n = 16). Therefore, a total of 1344 patients (59.5% male) were included in the analysis. The mean (SD) age was 68.7 (13.9) years. In total, 1025 patients (76.3%) had IS,

211 (15.7%) had ICH, 34 (2.5%) had SAH, and 74 (5.5%) had TIA.

Emergency medical services were used for emergency transport to the ED in 409 cases (30.4%). Table 1 presents the characteristics of patients who used EMS and those who did not. Patients who were more likely to use EMS for emergent transportation to the ED were older and had a higher level of education, hypertension, history of stroke, Atrial fibrillation , congestive heart failure, stroke occurring outside the home, a higher NIHSS score on arrival in the ED, and presentation symptoms such as weakness, numbness, altered consciousness, slurred speech/aphasia, and visual symptoms. In contrast, patients with symptoms of dizziness/vertigo/imbalance/ incoordination were less likely to use EMS. Multivariate logistic regression analysis showed that a higher level of education, a higher NIHSS score on arrival in the ED, AF, and altered consciousness at the onset of stroke were associated with use of EMS (Table 2). There was no difference in use of EMS among the different types of stroke.

Because acute IS is more time sensitive toward early Thrombolytic treatment, further analysis focused on this subgroup specifically. Of the 1025 patients with IS, 290 used EMS and 735 did not (Table 3). Older age, a higher level of education, hypertension, prior stroke, AF, congestive heart failure, smoking habits, and a higher NIHSS score on arrival in the ED were associated with use of EMS. The presenting symptoms of weakness, numbness, altered consciousness, slurred speech/aphasia, and visual problem were also significantly related to use of EMS. Multivariate logistic regression analysis showed that a higher level of education, altered consciousness at onset of stroke, a higher NIHSS score on arrival in the ED, and subtypes of IS were associated with use of EMS (Table 4). Patients with initial NIHSS scores of 15 to 24 (odds ratio [OR], 4.73; 95% confidence interval [CI],

790 N.-C. Chen et al. / American Journal of Emergency Medicine 31 (2013) 788791

Table 1

Comparison between patients with acute stroke with and without use of EMS (n = 1344)

Use of EMS

No use of EMS

P

Use of EMS (n = 290)

No use of EMS (n = 735)

P

(n = 409)

(n = 935)

Age (y), mean (SD)

73.0 (13.2)

69.0 (12.8)

b.001

Age (y), mean (SD)

71.0 (14.4)

67.7 (13.6)

b.001

Male

177 (61.0%)

431 (58.6%)

.482

Male

Level of education

249 (60.9%)

550 (58.8%)

.480

Level of education

None

43 (14.8%)

109 (14.8%)

.064

None

60 (14.7%)

129 (13.8%)

.153

1-6 y

62 (21.4%)

190 (25.9%)

1-6 y

89 (21.8%)

236 (25.2%)

7-12 y

94 (32.4%)

226 (30.7%)

7-12 y

132 (32.3%)

280 (29.9%)

N 12 y

83 (28.6%)

150 (20.4%)

N 12 y

115 (28.1%)

214 (22.9%)

Unknown

8 (2.8%)

60 (8.2%)

Unknown

Risk factors

13 (3.2%)

76 (8.1%)

Risk factors

Diabetes mellitus

95 (32.8%)

279 (38.0%)

.119

Diabetes mellitus

139 (34.0%)

337 (36.0%)

.468

Hypertension

232 (80.0%)

558 (75.9%)

.162

Hypertension

328 (80.2%)

710 (75.9%)

.087

Prior stroke

105 (36.2%)

220 (29.9%)

.052

Prior stroke

139 (34.0%)

266 (28.5%)

.042

AF

129 (44.5%)

114 (15.5%)

b.001

AF

144 (35.2%)

128 (13.7%)

b.001

Congestive heart failure

26 (9.0%)

34 (4.6%)

.008

Congestive heart failure

29 (7.1%)

38 (4.1%)

.019

Hypercholesterolemia

92 (31.7%)

237 (32.2%)

.872

Hypercholesterolemia

112 (27.4%)

279 (29.8%)

.362

Smoking habit

90 (31.0%)

195 (26.5%)

.138

Smoking habit

Place where stroke occurred

117 (28.6%)

246 (26.3%)

.375

Place where stroke occurred

Home

252 (86.9%)

633 (86.1%)

.187

Home

350 (85.6%)

819 (87.6%)

.084

Workplace

7 (2.4%)

19 (2.6%)

Workplace

9 (2.2%)

33 (3.5%)

Other place except home, hospital,

31 (10.7%)

53 (7.2%)

Other place except home, hospital,

50 (12.2%)

83 (8.9%)

and workplace

and workplace

NIHSS score on ED arrival, median (IQR) Type of stroke

IS

12 (5-19)

290 (70.9%)

3 (2-7)

735 (78.6%)

b.001 b.001

NIHSS score on ED arrival, median (IQR)

Subtypes of IS

Large artery atherothrombosis

11 (5-19)

53 (18.3%)

4 (2-6)

126 (17.1%)

b.001

b.001

ICH

92 (22.5%)

119 (12.7%)

Cardioembolism

131 (45.2%)

107 (14.6%)

SAH

11 (2.7%)

23 (2.5%)

Lacunar infarction

29 (10.0%)

234 (31.8%)

TIA

16 (3.9%)

58 (6.2%)

Other specific causes

8 (2.8%)

38 (5.2%)

Presentation symptoms/signs

Weakness

354 (86.6%)

678 (72.5%)

b.001

Undetermined cause

Presentation symptoms/signs

69 (23.8%)

230 (31.3%)

Numbness

263 (64.3%)

462 (49.4%)

b.001

Weakness

250 (86.2%)

548 (74.6%)

b.001

Altered consciousness

180 (44.0%)

113 (12.1%)

b.001

Numbness

191 (65.9%)

373 (50.8%)

b.001

Slurred speech/aphasia

305 (74.6%)

508 (54.3%)

b.001

Altered consciousness

112 (38.6%)

64 (8.7%)

b.001

Headache

33 (8.1%)

84 (9.0%)

.584

Slurred speech/aphasia

222 (76.6%)

413 (56.2%)

b.001

Visual problem

169 (41.3%)

173 (18.5%)

b.001

Headache

14 (4.8%)

43 (5.9%)

.520

Dizziness/vertigo/imbalance/

89 (21.8%)

264 (28.2%)

.013

Visual problem

126 (43.5%)

131 (17.8%)

b.001

Table 3

Comparison of patients with acute IS with and without use of EMS (n = 1025)

incoordination

Values are expressed as number (percentage), except for age and NIHSS scores.

Dizziness/Vertigo/Imbalance/ Incoordination

68 (23.5%) 215 (29.3%) .061

IQR, interquartile range.

2.25-9.94) were more likely to use EMS. Compared with patients with lacunar infarction, those with cardioembolism (OR, 3.04; 95% CI, 1.40- 6.60) and large artery atherothrombosis (OR, 2.10; 95% CI, 1.22-3.62) were more likely to use EMS.

  1. Discussion

Approximately 30% of the patients in our study used EMS. If we included all patients with known arrival route during the study period, the proportion of patients with stroke who used EMS would be similar to that reported in a prior study in a regional hospital in Taiwan [22] but relatively lower than some previous reports of 38% to 65% [28]. Awareness of stroke with recognition of symptoms is important in improving prehospital delay [29-32]. In other reports, symptoms of weakness and speech problems were most associated

Table 2

Multivariate analysis of factors related to use of EMS in patients with acute stroke

Values are expressed as number (percentage), except for age and NIHSS scores. IQR, interquartile range.

with increased use of EMS [16,27]. Among the 7 common symptoms of stroke that we categorized, altered consciousness was the only symptom that resulted in a call to EMS. Some studies have shown that patients with stroke would have arrived at the ED earlier if they had a disturbance in consciousness [33,34]. Emergency medical services may be called not because stroke is recognized or suspected, but because it is believed that the severe symptoms may be life threatening [35]. It is also possible that stroke is suspected, but the patient would rather go to the hospital by another Mode of transportation instead of EMS. Our study reveals that more public education programs regarding the identification of symptoms of stroke and the need to call EMS immediately if stroke is suspected are needed to decrease prehospital delay. In addition, more efforts are

Table 4

Multivariate analysis of factors related to use of EMS in patients with acute IS

? OR 95% CI P

Level of education ( 3/4 6 y vs b 6 y) 0.5327 1.70 1.19-2.44 .004

?

OR

95% CI

P

Initial NIHSS score on ED arrival

b5

1.00

Level of education

0.5243

1.69

1.25-2.29

b.001

5-14

0.8683

2.38

1.49-3.80

b.001

( 3/4 6 y vs b 6 y)

15-24

1.5547

4.73

2.25-9.94

b.001

Initial NIHSS score on ED arrival

0.0759

1.08

1.05-1.11

b.001

N 25

1.3237

3.76

1.31-10.78

.014

AF

0.8862

2.43

1.71-3.44

b.001

Altered consciousness

0.9023

2.47

1.47-4.15

b.001

Altered consciousness

0.6324

1.88

1.25-2.84

.003

Subtypes of IS

Types of stroke

Lacunar infarction

1.00

IS, TIA

1.00

Large artery atherothrombosis

0.7405

2.10

1.22-3.62

.008

ICH

0.0222

1.02

0.68-1.54

.925

Cardioembolism

1.1122

3.04

1.40-6.60

.005

SAH

-0.5382

0.58

0.20-1.73

.332

Undetermined or other specific causes

0.4852

1.63

0.93-2.85

.090

N.-C. Chen et al. / American Journal of Emergency Medicine 31 (2013) 788791 791

required to understand why patients with stroke are reluctant to use EMS and then try to resolve the barriers to use of EMS.

In addition to altered consciousness, our study showed that the initial severity of stroke was related to use of EMS, especially in patients with initial NIHSS scores of 15 to 24. It is reasonable that patients with a higher severity of stroke tend to call for help from professional EMS because the condition of such patients is viewed as serious [33,36]. In addition, moving patients with higher NIHSS scores to the hospital via other modes of transportation is more difficult than via EMS, which provides at least 2 EMTs who can provide medical assistance as well as move the patient with a stretcher and transport the patient to the ED by ambulance. We also found that AF was an independent factor for use of EMS in patients with stroke, and patients with a cardioembolic stroke were more likely to use EMS. Approximately 15% of all strokes are embolic strokes, and the embolus suddenly blocks the recipient site so that the onset of symptoms is abrupt and usually maximal at the start. Because of the abrupt manifestation of symptoms, these patients may be more alert to the abnormalities and seek immediate help. In our study, patients with large artery atherothrombosis were also more likely to arrive at the ED by EMS than patients with lacunar infarction. The hypothesis is that large artery atherothrombosis may cause more types of symptoms of stroke at the same time than lacunar infarction and thus is easily viewed as an emergency.

Patients with a higher level of education were more likely to use EMS in our study; these patients may have more of an opportunity to learn about stroke. Mikulik et al [37] conducted a national survey and concluded that the decision to use EMS was influenced by the knowledge that stroke is a serious and treatable disease and not by recognition of symptoms. Education should therefore enhance symptom recognition and time-sensitive treatability with immediate activation of EMS, and then stroke will not be missed or delayed in diagnosis.

A prior study concluded that hemorrhagic stroke is independently predictive of use of EMS despite adjustment for the severity of stroke [36], and the result is speculated to be caused by a symptom-specific effect. The analysis in our study removed such an effect by adjusting for the symptoms of stroke, and the results did not show that the type of stroke was associated with use of EMS.

There are some limitations to the present study. First, we did not know the environment where the patients lived and the prestroke status of the patients; these factors may affeCT utilization by patients or their family members. For example, EMS may be used when a patient is bedridden and lives in a high-rise building without an elevator. Second, we did not evaluate and adjust the severity of each symptom individually but used only the NIHSS score on arrival in the ED to measure the severity of stroke. A patient with Severe headache with a pain score of 10 may use EMS, but his or her NIHSS score may be zero. This may cause some bias. Third, we did not evaluate the knowledge and awareness of stroke and attitudes toward EMS in patients with stroke, which may affect the motivation to use EMS.

  1. Conclusion

Emergency medical services have not yet been widely used by patients experiencing stroke in Taiwan. We found that patients with a higher level of education, altered consciousness, a higher NIHSS score on arrival in the ED, a history of AF, and cardioembolic stroke were more likely to use EMS for emergent transportation. More efforts are needed to increase public awareness of stroke and, most importantly, the prompt use of EMS once the symptoms of stroke are recognized.

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