Paramedic Diagnosis of StrokeExamining Long-Term Use of the Melbourne Ambulance Stroke Screen

(MASS) in the Field

Janet E. Bray, PhD(C); Kelly Coughlan, BS; Bill Barger, ADHS; Chris Bladin, MD

Background and Purpose—Recent evidence suggests the Cincinnati Prehospital Stroke Scale is ineffectively used andlacks sensitivity and specificity. Melbourne (Australia) paramedics have been using the Melbourne Ambulance StrokeScreen (MASS) since 2005. The aim of this study was to review the real-world use of MASS 3 years after citywideimplementation.

Methods—Two groups of consecutively admitted patients to an Australian hospital between January and May 2008 wereused: (1) patients for whom paramedics performed MASS; and (2) patients with a discharge diagnosis of stroke ortransient ischemic attack. Use of MASS was examined for all transports and for patients diagnosed with stroke ortransient ischemic attack. The sensitivity and specificity of paramedic diagnosis, MASS, and Cincinnati PrehospitalStroke Scale were calculated. Paramedic diagnosis of stroke among patients with stroke was statistically compared withthose obtained immediately post-MASS implementation in 2002.

Results—For the study period, MASS was performed for 850 (16%) of 5286 emergency transports, including 199 of 207(96%) patients with confirmed stroke and transient ischemic attack. In patients in whom MASS was performed (n�850),the sensitivity of paramedic diagnosis of stroke (93%, 95% CI: 88% to 96%) was higher than the MASS (83%, 95%CI: 77% to 88%, P�0.003) and equivalent to Cincinnati Prehospital Stroke Scale (88%, 95% CI: 83% to 92%,P�0.120), whereas the specificity of the paramedic diagnosis of stroke (87%, 95% CI: 84% to 89%) was equivalent toMASS (86%, 95% CI: 83% to 88%, P�0.687) and higher than Cincinnati Prehospital Stroke Scale (79%, 95% CI: 75%to 82%, P�0.001). The initial improvement in stroke paramedic diagnosis seen in 2002 (94%, 95% CI: 86% to 98%)was sustained in 2008 (89%, 95% CI: 84% to 94%, P�0.19).

Conclusion—In our experience, paramedics have successfully incorporated MASS into the assessment of neurologicallycompromised patients. The initial improvement to the paramedics’ diagnosis of stroke with MASS was sustained 3 yearsafter citywide implementation. (Stroke. 2010;41:1363-1366.)

Key Words: ambulance � diagnosis � emergency services � stroke

Emergency medical services (EMS) are an integral partof the acute stroke team.1 They are fundamental in

maximizing the delivery of thrombolytic therapy to pa-tients with stroke by correctly identifying stroke in thefield, transporting patients with suspected stroke to acutestroke centers, and activation of Code Stroke Teamsthrough prehospital notification.2,3

A variety of prehospital stroke screens have been devel-oped to assist EMS to identify patients with stroke in the field(Table 1).4–7 Our previous work confirmed the value in usingthese screens, showing an immediate improvement in EMSdiagnosis of stroke from a baseline of 78% to 94% aftereducation and with use of the Melbourne Ambulance StrokeScreen (MASS).8 However, recent investigations of a similarscreen, the Cincinnati Prehospital Stroke Scale (CPSS),

suggest poor use by paramedics and low sensitivity andspecificity.9,10 Additionally, no long-term evaluations of theuse of prehospital screens have been conducted.

The aim of this study was to examine the use of MASS inthe field 3 years after citywide education and implementation,specifically determining the use of MASS by paramedics andto calculate and compare the sensitivity and specificity ofMASS, CPSS, and paramedic diagnosis of stroke to ourprevious findings.

Subjects and MethodsThis study was a cross-sectional design of consecutive patientstransported by EMS to an Australian hospital between January andMay 2008. Methods are summarized in the Figure. Institutionalethical approval was received before the start of data collection.

Received December 3, 2009; final revision received February 8, 2010; accepted February 27, 2010.From Box Hill Hospital and Deakin University (J.E.B.), Victoria, Australia; Box Hill Hospital (K.C.), Victoria, Australia; Ambulance Victoria (B.B.),

Victoria, Australia; and Box Hill Hospital and Monash University (C.B.), Victoria, Australia.Correspondence to Chris Bladin, MD, Box Hill Hospital, Department of Neurosciences, 5 Arnold Street, Box Hill, Victoria, 3128, Australia. E-mail

chris.bladin@easternhealth.org.au© 2010 American Heart Association, Inc.

Stroke is available at http://stroke.ahajournals.org DOI: 10.1161/STROKEAHA.109.571836

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Emergency Medical SystemThe Victorian EMS is described in detail elsewhere.8 In brief,Ambulance Victoria services 5 million people in the state ofVictoria, Australia. Ambulance Victoria uses the Advanced MedicalPriority Dispatch System with a 2-tiered response: Advanced LifeSupport paramedics and Mobile Intensive Care paramedics and takesapproximately 387 000 emergency calls per year. The training ofAdvanced Life Support paramedics required 3 years of universitystudy and a 1-year graduate program. Mobile Intensive Care para-medics have additional education and operate at an independentpractitioner level.

All paramedics received a 1-hour stroke education program andinstruction on the use of MASS in 2004 to 2005. Paramedics performthe 3 MASS physical assessments (facial droop, hand grip, andspeech) in conscious but neurologically compromised patients of noobvious cause such as drug overdose or trauma. If these assessmentsare positive for stroke, they obtain the remaining MASS historyitems and perform a blood sugar level to rule out stroke mimics andsuitability for thrombolysis. If the MASS is still positive and thestroke is acute, paramedics transport the patient with suspectedstroke to the nearest acute stroke center and activate the hospitals“Code Stroke Team” by calling the emergency department en route.

Hospital SettingBox Hill Hospital (BHH), located in the eastern suburbs of Mel-bourne, admits approximately 500 patients with stroke per year. Allpatients with a confirmed diagnosis of stroke by neuroimaging or

with a discharge diagnosis of transient ischemic attack (TIA)admitted to the hospital are entered into the Stroke/TIA registry.

SubjectsTwo groups of patients admitted to BHH were used in this study: (1)patients transported by EMS with documented MASS assessments ofhand grip, speech, and facial weakness; and (2) patients with adischarge diagnosis of stroke or TIA included in the Stroke/TIAregistry. Patients who were unconscious or asymptomatic at the timeof paramedic assessment were excluded (n�49).

Data CollectedData were accessed through the Victorian Ambulance ClinicalInformation System and BHH Stroke/TIA registry. The VictorianAmbulance Clinical Information System allows paramedics to elec-tronically record patient information and to access protocols andprompts for additional assessments that may be completed at thescene. The patient’s name, MASS assessments, and paramedicdiagnosis were retrieved. This data were crossreferenced against theBHH Stroke/TIA registry (name, date, gender, and age) to determineif the discharge diagnosis was stroke or TIA. For patients with strokeand TIA with no MASS documentation (n�8), MASS and CPSSwere retrospectively applied based on the paramedic assessment.

Statistical AnalysisThe sensitivity, specificity, positive and negative predictive values,and 95% CIs were calculated for MASS (positive or negative), CPSS(positive or negative), and paramedic diagnosis of stroke/TIA (yes orno) using the discharge diagnosis of stroke/TIA (yes or no). Thesewere statistically compared in SPSS (Version 17.0) using the �2 test.A probability value �0.05 was considered statistically significant.

ResultsUse of MASSOf the 5286 emergency transports to BHH, 1004 (18%) wereconscious but neurologically compromised with no immedi-

Table 1. Comparison of Validated Prehospital Stroke Screens

Assessment LAPSS CPSS MASS OPSS

Assessments suggesting stroke

Unilateral facial droop orweakness

X X X X

Unilateral arm drift or weakness X X X

Unilateral hand grip weakness X X

Unilateral leg weakness X

Slurred or abnormal speech ormute

X X X

Assessments ruling out strokemimics

Age �45years

X X

History of seizure orepilepsy

X X X

Abnormal blood glucoselevel

X X X

Symptoms have resolved X

Additional criteria for thrombolysisineligibility

Can be transported within 2 hoursof onset

X

At baseline, wheelchair orbedridden

X X

Glasgow coma Scale �10 X

Terminally ill or palliativecare

X

Triage Level 1 and/or uncorrectedairway, breathing or circulationproblem

X

LAPSS indicates Los Angeles Prehospital Stroke Screen; OPSS, OntarioPrehospital Stroke Scale.

Figure. Flow chart of methods.

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ately obvious cause. MASS was documented for 850: 16% ofall transports and 85% of conscious neurologically compro-mised patients.

For the same period, 199 (96%) of 207 confirmed strokeor TIA admissions transported by EMS had MASS docu-mentation. Patients with no MASS documentation (n�8)were posterior ischemic strokes (n�4), parietal intracere-bral hemorrhages (n�3), and a TIA (n�1; Table 2); 4 ofthese patients had documentation of confusion and 2 werenon-English-speaking.

Sensitivity and Specificity Analysis for PatientsWith Documented MASSFor patients with documented MASS, the sensitivity of theparamedic diagnosis of stroke was higher than MASS (93%versus 83%, P�0.003) and equivalent to CPSS (93% versus88%, P�0.120; Table 3). In contrast, the specificity of theparamedic diagnosis of stroke was equivalent to MASS (87%versus 85%, P�0.687) and higher than CPSS (87% versus79%, P�0.001). The MASS demonstrated equivalent sensi-tivity to the CPSS (P�0.149) and higher specificity(P�0.001).

Paramedic Diagnosis in Patients With Strokeand TIAThe improvement seen in stroke paramedic diagnosis afterthe introduction of MASS in a pilot group in 2002 (n�78 of83 [94%], 95% CI: 86% to 98%) was sustained in 2008(n�184 of 207 [89%], 95% CI: 84% to 94%, P�0.19). Of the22 cases in which EMS did not diagnose stroke, 63% (n�14)did not meet MASS criteria for stroke, 14% (n�3) wereMASS-positive, and 23% (n�5) did not have MASSdocumented.

DiscussionOur large study demonstrated high use of MASS in the fieldby paramedics and confirms the value of such screens in theidentification of stroke. The excellent initial improvement inthe diagnosis of stroke by paramedics after the pilot study ofMASS8 was sustained 3 years after citywide education andMASS implementation.

The strengths of this study are that it examined the“real-world” use of prehospital stroke screens as used byparamedics and is 1 of a few studies to examine thesescreening tools outside of screening tool validation studies.

Table 2. Patients With Stroke and TIA With No MASS Documentation (n�8)

Age Gender Resides Stroke Subtype Symptoms Paramedic Diagnosis MASS Symptom

1. 74 F Nursing home Ischemic—cerebella Dizziness, unsteady gait, vomiting(non-English-speaking)

Vertigo No

2. 87 F Nursing home Ischemic—posterior Fever, drowsy, nausea, confusedspeech

Confusion Yes—speech

3. 86 M Retirement village ICH—frontoparietal Confusion, incontinence UTI/confusion Yes—speech

4. 68 M Home ICH—parietal Repetitive questioning,incontinence, fall withforehead hematoma

Altered conscious state postheadstrike

Yes—speech

5. 74 F Home Ischemic—cerebella Nausea Nausea No

6. 86 M Nursing home Ischemic—cerebella Fall (non-English-speaking) Collapse No

7. 67 F Home TIA Dizziness, headache Migraine No

8. 70 M Nursing home ICH—parietal–temporal Confused, unsteady gait(Alzheimer)

Confusion Yes—speech

F indicates female; M, male; ICH, intracerebral hemorrhage; UTI, urinary tract infection.

Table 3. The Raw Data and Sensitivity Analysis of Paramedic Stroke/TIA Diagnosis, MASS and CPSS

Patients With Documented MASS (n�850)Patients With Documented MASS (n�850)�Patients With

Stroke/TIA With No Documented MASS (n�8)

Paramedic Diagnosis MASS CPSS Paramedic Diagnosis MASS CPSS

Sensitivity 185/199 166/199 176/199 185/207 170/207 180/207

93% (88–96) 83% (77–88) 88% (83–92) 89% (84–93) 82% (76–87) 87% (81–91)

Specificity 564/651 559/651 513/651 564/651 559/651 513/651

87% (84–89) 85% (83–88) 79% (75–82) 87% (84–89) 85% (83–88) 79% (75–82)

PPV 185/272 166/258 176/314 185/272 170/262 180/318

68% (62–73) 64% (58–67) 56% (50–62) 68% (62–73) 64% (59–71) 57% (51–62)

NPV 564/578 559/592 513/536 564/586 559/596 513/540

98% (96–99) 94% (92–96) 96% (94–97) 96% (94–98) 94% (91–96) 95% (93–97)

PPV indicates positive predictive value; NPV, negative predictive value.

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However, the findings of this study must be considered inlight of its weaknesses. First, the final diagnosis of TIA reliedon a discharge diagnosis of TIA, and not all patients with trueTIA may have been correctly diagnosed at discharge. Second,positive and negative predictive values are influenced by theprevalence of disease. Because only 23% of all patients withdocumented MASS were diagnosed as having stroke or TIA,these figures may not reflect true values. Lastly, it is possiblethat MASS was only performed in patients paramedicsstrongly suspected had experienced a stroke. This may haveartificially inflated the specificity of the screen tools byexcluding false-positives and explain the better performanceof CPSS compared with previous reports.9,10

Another finding that conflicts with recently publishedstudies in this area9,10 is the improvement in paramedics’diagnosis of stroke. This disparity may be explained bydifferences in the samples studied. The previous studiesreporting lower paramedic identification of stroke only ex-amined patients with a paramedic diagnosis of stroke or apositive stroke screen, whereas we extended this to include allpatients with documented MASS (positive and negativestroke screen). An additional explanation could be differencesin paramedic training between Australia and the UnitedStates, which may also explain differences found in the use ofstroke screens.

Recent work by Frendl et al reported poor use (37.5%) ofthe CPSS by paramedics in patients with stroke with noimprovement after paramedic education.10 However, use ofthe MASS in our study was high (85% of conscious neuro-logically impaired patients transported and 96% of patientswith stroke). A review of the patients with MASS showed themajority presented with neurological problems and unex-plained falls. As discussed in a previous report,11 we attributesome of our success to our feedback system. For the first 18months after education, we provided the transporting para-medics with the outcome of patients receiving thrombolytictherapy. This allowed us the opportunity to provide a re-minder about MASS and to give feedback to paramedicsabout their contribution to successful patient outcomes.

Previous work has demonstrated that paramedic diagnosisof stroke results in faster in-hospital times12 and improvingparamedic diagnosis of stroke with the use of paramedicstroke screening tools has been linked to increasingthrombolytic therapy rates to as high as 21%.13 In ourhospital, thrombolytic therapy rates improved from 5%8 to11%14 after the combined implementation of MASS and anin-hospital code stroke system.

In summary, our large study indicates that paramedics havesuccessfully incorporated MASS into their assessment ofneurologically compromised patients and that correct para-medic diagnosis of stroke remained consistently high 3 yearsafter citywide implementation of MASS. Paramedic diagno-

sis of stroke was higher than the MASS, indicative of asuccessful stroke education program.

AcknowledgmentsWe acknowledge Melissa Wright for her assistance with datacollection and entry.

DisclosuresJ.E.B. received a National Heart Foundation Research Scholarship.

References1. Acker JE III, Pancioli AM, Crocco TJ, Eckstein MK, Jauch EC, Larrabee

H, Meltzer NM, Mergendahl WC, Munn JW, Prentiss SM, Sand C, SaverJL, Eigel B, Gilpin BR, Schoeberl M, Solis P, Bailey JR, Horton KB,Stranne SK. Implementation strategies for emergency medical serviceswithin stroke systems of care: a policy statement from the AmericanHeart Association/American Stroke Association Expert Panel onEmergency Medical Services Systems and the Stroke Council. Stroke.2007;38:3097–3115.

2. Belvis R, Cocho D, Marti-Fabregas J, Pagonabarraga J, Aleu A,Garcia-Bargo MD, Pons J, Coma E, Garcia-Alfranca F, Jimenez-FabregaX, Marti-Vilalta JL. Benefits of a prehospital stroke code system. Feasi-bility and efficacy in the first year of clinical practice in Barcelona, Spain.Cerebrovasc Dis. 2005;19:96–101.

3. Abdullah AR, Smith EE, Biddinger PD, Kalenderian D, Schwamm LH.Advance hospital notification by EMS in acute stroke is associated withshorter door-to-computed tomography time and increased likelihood ofadministration of tissue-plasminogen activator. Prehosp Emerg Care.2008;12:426–431.

4. Kothari RU, Pancioli A, Liu T, Brott T, Broderick J. Cincinnati Pre-hospital Stroke Scale: reproducibility and validity. Ann Emerg Med.1999;33:373–378.

5. Kidwell CS, Starkman S, Eckstein M, Weems K, Saver JL. Identifyingstroke in the field. Prospective validation of the Los Angeles PrehospitalStroke Screen (LAPSS). Stroke. 2000;31:71–76.

6. Bray JE, Martin J, Cooper G, Barger B, Bernard S, Bladin C. Paramedicidentification of stroke: community validation of the MelbourneAmbulance Stroke Screen. Cerebrovasc Dis. 2005;20:28–33.

7. Chenkin J, Gladstone DJ, Verbeek PR, Lindsay P, Fang J, Black SE,Morrison L. Predictive value of the Ontario Prehospital Stroke Screeningtool for the identification of patients with acute stroke. Prehosp EmergCare. 2009;13:153–159.

8. Bray JE, Martin J, Cooper G, Barger B, Bernard S, Bladin C. Aninterventional study to improve paramedic diagnosis of stroke. PrehospEmerg Care. 2005;9:297–302.

9. Ramanujam P, Guluma KZ, Castillo EM, Chacon M, Jensen MB, Patel E,Linnick W, Dunford JV. Accuracy of stroke recognition by emergencymedical dispatchers and paramedics—San Diego experience. PrehospEmerg Care. 2008;12:307–313.

10. Frendl DM, Strauss DG, Underhill BK, Goldstein LB. Lack of impact ofparamedic training and use of the Cincinnati Prehospital Stroke Scale onstroke patient identification and on-scene time. Stroke. 2009;40:754–756.

11. Bray JE, Bladin C. Success with paramedic diagnosis of stroke. Stroke.2009;40:e398.

12. Mosley I, Nicol M, Donnan G, Patrick I, Kerr F, Dewey H. The impactof ambulance practice on acute stroke care. Stroke. 2007;38:2765–2770.

13. Quain DA, Parsons MW, Loudfoot AR, Spratt NJ, Evans MK, RussellML, Royan AT, Moore AG, Miteff F, Hullick CJ, Attia J, McElduff P,Levi CR. Improving access to acute stroke therapies: a controlled trial oforganised pre-hospital and emergency care. Med J Aust. 2008;189:429–433.

14. Bray JE, Coughlan K, Bladin C. Thrombolytic therapy for acuteischaemic stroke: successful implementation in an Australian tertiaryhospital. Intern Med J. 2006;36:483–488.

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Janet E. Bray, Kelly Coughlan, Bill Barger and Chris BladinStroke Screen (MASS) in the Field

Paramedic Diagnosis of Stroke: Examining Long-Term Use of the Melbourne Ambulance

Print ISSN: 0039-2499. Online ISSN: 1524-4628 Copyright © 2010 American Heart Association, Inc. All rights reserved.

is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231Stroke doi: 10.1161/STROKEAHA.109.571836

2010;41:1363-1366; originally published online June 10, 2010;Stroke. 

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25

Bray et al Examining Long-Term Use of the MASS in the Field

Original Contributions

卒中的院前诊断：

墨尔本急救卒中筛查量表 (Melbourne Ambulance Stroke Screen, MASS)长期实际应用的检验

Paramedic Diagnosis of Stroke: Examining Long-Term Use of the Melbourne Ambulance Stroke Screen (MASS) in the Field

Janet E. Bray, PhD(C); Kelly Coughlan, BS; Bill Barger, ADHS; Chris Bladin, MD

背景及目的：近期有证据提示辛辛那提院前卒中评估量表 (Cincinnati Prehospital Stroke Scale，CPSS) 未得到有

效使用，且敏感性及特异性不高。墨尔本 ( 澳大利亚 ) 院前急救人员自 2005 年起一直使用“墨尔本急救卒中

筛查”(Melbourne Ambulance Stroke Screen，MASS) 量表。本研究在 MASS 全市应用三年后进行，旨在对该

量表的实际应用情况进行评估。

方法：研究对象纳入 2008 年 1-5 月连续收住澳大利亚医院的患者，分为两组：(1) 接受 MASS 院前评估的患

者；(2) 出院诊断为卒中或短暂性脑缺血发作 (Transient Ischemic Attack，TIA) 患者，对所有针对急诊转运及诊

断为卒中或 TIA 患者进行的 MASS 评估进行检验。分别计算出院前诊断、MASS 及 CPSS 的敏感性和特异性，

并将卒中患者的院前诊断数据与 2002 年前版 MASS 刚实施时的数据进行统计学比较。

结果：研究期间共有 5286 名急诊转运病人，有 850 人 (16%) 接受了 MASS 评估，其中确诊为卒中和 TIA 者

199 人，占所有确诊为卒中和 TIA 的患者 (n=207) 的 96%。在接受 MASS 评估的患者中 (n=850)，卒中院前诊

断的敏感性为 93%(95% CI ：88%-96%)，显著高于 MASS 的敏感性 (83%，95% CI ：77%-88%，P=0.003)，与

CPSS 敏感性相当 (88%，95% CI ：83%-92%，P=0.120)。卒中院前诊断的特异性为 87%(95% CI ：84%-89%)，与 MASS 特异性无显著差异 (86%，95% CI ：83%-88%，P=0.687)，但显著高于 CPSS 特异性 (79%，95% CI ：75%-82%，P<0.001)。2002 年 MASS 初步实施后卒中院前诊断率得到的改善 (94%，95% CI ：86%-98%)，在

2008 年仍得以保持 (89%，95% CI ：84%-94%，P=0.19)。结论：本研究提示，MASS 已经被成功地运用于神经功能缺损患者的院前急救评估，其对卒中院前诊断率的

改善在全市应用三年仍得以维持。

关键词：急救，诊断，急诊服务，卒中

(Stroke. 2010;41:1363-1366.　安冉 黄纯臣 译 董强 校 )

From Box Hill Hospital and Deakin University (J.E.B.), Victoria, Australia; Box Hill Hospital (K.C.), Victoria, Australia; Ambulance Victoria (B.B.), Victoria, Australia; and Box Hill Hospital and Monash University (C.B.), Victoria, Australia.

Correspondence to Chris Bladin, MD, Box Hill Hospital, Department of Neurosciences, 5 Arnold Street, Box Hill, Victoria, 3128, Australia. E-mail chris.bladin@eastern-health.org.au

© 2010 American Heart Association, Inc.

急诊医疗服务 (Emergency Medical Services，EMS)是急性卒中团队的基本组成部分 [1]。它通过在急救

现场准确识别卒中，并将可疑卒中患者及时转运至

急性卒中中心，以及院前告知启动卒中急救小组

(Code Stroke Teams)[2,3]，从而使卒中患者得到最大限

度的溶栓治疗。

目前已有多个卒中院前筛查量表应用于 EMS，以辅助其在现场识别卒中患者 ( 表 1)[4-7]。我们既

往的一项研究显示，在经过“墨尔本急救卒中筛

查”(Melbourne Ambulance Stroke Screen，MASS) 量

表培训及应用后，EMS 对卒中的识别率得到了迅速

地提高，从基线水平的 78% 上升至 94%[8]，从而肯

定了卒中筛查量表的应用价值。但近期对类似的筛

查量表辛辛那提院前卒中评估量表 (Cincinnati Pre-hospital Stroke Scale，CPSS) 的研究发现，其在院前

评估中应用度不佳，且敏感性及特异性都较低 [9,10]。

此外，尚无研究对院前筛查量表的应用进行长期评估。

本研究于 MASS 在全市开展培训和应用三年后

进行，旨在对该量表的实际应用情况进行检验，尤

其是要明确 MASS 在院前急救中的应用情况，以及

26

Stroke July 2010

比较 MASS、CPSS 和院前诊断的敏感性、特异性，

并与我们之前的卒中院前诊断研究结果进行比较。

研究对象与方法本研究为横断面研究，研究对象为 2008 年 1-5

月期间经 EMS 连续收入澳大利亚医院的患者。方法

如流程图所示。本研究在开始数据收集之前已通过

伦理认证。

急诊医疗系统

关于维多利亚 EMS 的介绍在其它研究中已有

详述 [8]。简言之，维多利亚急诊系统为澳大利亚维

多利亚洲的 5 000 000 人群提供服务，它采用高级医

疗优先调度系统 (Advanced Medical Priority Dispatch System)，每年接受约 387 000 个急诊呼叫，它有两

个应答级别：高级生命支持院前救护及移动重症监

护救护。高级生命支持院前救护的培训包括三年大

学课程及一年研究生项目。移动重症监护救护则需

要在独立行医的水平上接受额外的培训和操作锻炼。

所有的院前急救人员皆于 2004-2005 年接受过

一小时卒中培训项目以及 MASS 的应用指导。接受

MASS 评估的患者需符合有意识且存在神经功能受

损，同时排除药物过量、外伤等明确病因。首先进

行 MASS 体检评估，包括三个方面 ( 面部检查、握

力检查及言语检查 )，如这些评估结果支持卒中诊断，

则接下来进行 MASS 相关病史项目的询问及血糖水

平检查，以排除卒中样发作，并评价是否能进行溶

栓。如此时 MASS 仍支持卒中诊断并且在时间窗内，

则将疑似卒中的患者经急诊转运至最近的急性卒中

中心，并通过在途中呼叫急诊部门，启动医院的“卒

中急救团队”。

医院设置

Box Hill 医院 (Box Hill Hospital，BHH) 位于墨

尔本的东部市郊，每年约接收 500 名中风患者。所

有经神经影像学确诊的卒中患者，或是出院诊断为

TIA 的患者，均被纳入中风 /TIA 登记系统。

研究对象

有两组收入 BHH 的患者纳入本研究：(1) 通过

EMS 转运，且有记录 MASS 评估时握力、言语及面

瘫检查相关信息的患者；(2) 在卒中 /TIA 登记系统

中出院诊断为卒中或 TIA 患者。排除在院前评估时

昏迷及无症状患者 49 人。

数据收集

所有数据通过维多利亚急诊临床信息系统及

BHH 卒中 /TIA 登记系统获得。通过维多利亚急诊

临床信息系统，院前急救人员可记录患者的电子信

息，并获得有助于完成其它现场评估的流程提示，

患者姓名、MASS 评估结果及院前诊断可在此系统

中进行检索。它与 BHH 卒中 /TIA 登记系统的相关

数据 ( 姓名、日期、性别和年龄 ) 可交叉引用，从

表 1　卒中院前筛查量表的比较评估 LAPSS CPSS MASS OPSS支持卒中 　一侧面部下垂或无力 × × × ×

　一侧手臂下垂或无力 × × ×

　一侧握力下降 × × 　一侧下肢无力 ×

　言语不清或不能言语 × × ×

排除类似卒中发作 　年龄 <45 岁 × × 　癫痫发作史 × × ×

　血糖水平异常 × × ×

　症状消失 ×

其它溶栓排除标准 　可在发作后两小时内进行转运 ×

　发病前依靠轮椅或卧床不起 × × 　Glasgow 评分 <10 ×

　疾病终末期或接受临终关怀 ×

　急诊服务分流级别为 Level 1， ×

　和 / 或存在气道、呼吸或循环系统异常

LAPSS：洛杉矶院前卒中筛查量表 (Los Angeles Prehospital Stroke Screen)； OPSS ：安大略院前卒中量表 (Ontario Prehospital Stroke Scale)

图　研究流程图

1、通过维多利亚急诊临床信息系统获得所有于 2008 年 1-5 月

转运至 BHH 的患者 MASS 评估信息，包括面瘫检查、握力检

查及语言检查

2、确定 MASS 和 CPSS 卒中筛查是否阳性，以及院前诊断是

否为卒中

3、与卒中 /TIA 登记系统的诊断信息进行对照，计算 MASS、CPSS 及院前诊断的敏感性、特异性，并进行统计学比较

4、检验卒中 /TIA 患者的院前诊断率，并与 MASS 初步实施后

的院前诊断水平 (94%) 进行统计学比较

27

Bray et al Examining Long-Term Use of the MASS in the Field

而确定患者的出院诊断是否为卒中或 TIA。在诊断

为卒中和 TIA 患者中，有 8 人无 MASS 评估记录，

则通过院前评估记录对其进行回顾性的 MASS 及

CPSS 评估。

统计分析

本研究以出院诊断是否为卒中 /TIA( 是 / 否 ) 为临床诊断标准，计算 MASS( 阳性 / 阴性 )、CPSS( 阳性 / 阴性 )，及院前诊断为卒中或 TIA( 是 / 否 ) 的敏

感性、特异性，阳性预测值、阴性预测值及 95% 可

信区间 (95% CIs)。采用 SPSS(17.0 版本 ) 软件中 χ2

检验进行数据分析，P<0.05 被认为有统计学意义。

结果MASS的应用

在急诊转运至 BHH 的 5286 名患者中，有 1004人 (18%) 符合有意识且存在神经功能受损，并且无

明确病因的纳入标准，其中 850 人有 MASS 评估记

录，占所有转运患者的 16%，占有意识且存在神经

功能受损患者的 85%。

在相同时间段内，有 207 名患者经 EMS 转运入

院并确诊为卒中或 TIA，其中 199(96%) 人有 MASS记录。无 MASS 记录者有 8 人，包括后循环缺血性

卒中 4 人，合并部分颅内出血 3 人，TIA 1 人 ( 见表 2)；

4 人记录不详，2 人语言为非英语语种。

经MASS评估的患者中敏感性和特异性分析

在有 MASS 评估记录的患者中，卒中院前诊断

的敏感性高于 MASS(93% vs. 83%，P=0.003)，与

CPSS 敏感性相当 (93% vs. 88%，P=0.120，见表 3)。而卒中院前诊断的特异性与 MASS 相比无统计学差

异 (87% vs. 85%，P=0.687)，但显著高于 CPSS 特异

性 (87% vs. 79%，P<0.001)。MASS 与 CPSS 敏感度

相当 (P=0.149)，但特异性较 CPSS 高 (P=0.001)。

卒中和TIA患者的院前诊断

在 2002 年初步应用 MASS 的研究群体中，卒

中院前诊断的识别率达到 94%(n=78 /83，95% CI ：86%-98%)，2008 年则为 89%(n=184/ 207 , 95% CI ：84%-94%)，与之前 MASS 对院前诊断水平相当

(P=0.19)。在 22 例 EMS 未诊断出卒中的患者中，

63% (n=14)未达到MASS的卒中诊断标准，14% (n=3)为 MASS 阳性，23%(n=5) 无 MASS 评估记录。

讨论本项大样本研究提示了 MASS 在院前急救中的

高利用率，并明确了其对卒中识别的价值。MASS于全市推行应用三年之后，其在前期研究中对院前

表 2　无 MASS 记录的卒中 /TIA 患者 (n=8) 年龄 性别 住所 卒中类型 症状 院前诊断 MASS 症状

1. 74 女 护理院 小脑缺血 头昏、步态不稳、呕吐 ( 非英语语言 ) 眩晕症 无

2. 84 女 护理院 后循环缺血 发热、嗜睡、恶心、言语含糊 意识模糊 有 - 言语症状

3. 86 男 养老院 额顶叶出血 间断性意识模糊 尿路感染 / 意识模糊 有 - 言语症状

4. 68 男 在家 顶叶出血 间断性重复提问，跌倒后形成前额血肿 前额撞击后意识状态改变 有 - 言语症状

5. 74 女 在家 小脑缺血 恶心 恶心 无

6. 86 男 护理院 小脑缺血 跌倒 ( 非英语语言 ) 跌倒发作 无

7. 67 女 在家 TIA 头昏、头痛 偏头痛 无

8. 70 男 护理院 顶颞叶出血 意识模糊、步态不稳 (Alzheimer) 意识模糊 有 - 言语症状

表 3　院前卒中 /TIA 诊断、MASS 和 CPSS 的原始数据及敏感性分析 　　　　　　有 MASS 记录患者 (n=850)+ 　　　　　 有 MASS 记录的患者 (n=850) 　　　　无 MASS 记录的卒中 /TIA 患者 (n=8) 院前诊断 MASS CPSS 院前诊断 MASS CPSS敏感性 185/199 166/199 176/199 185/207 170/207 180/207 93%(88–96) 83%(77–88) 88% (83–92) 89% (84–93) 82%(76–87) 87%(81–91)特异性 564/651 559/651 513/651 564/651 559/651 513/651 87%(84–89) 85%(83–88) 79% (75–82) 87% (84–89) 85% (83–88) 79%(75–82)PPV 185/272 166/258 176/314 185/272 170/262 180/318 68%(62–73) 64%(58–67) 56% (50–62) 68% (62–73) 64% (59–71) 57%(51–62)NPV 564/578 559/592 513/536 564/586 559/596 513/540 98%(96–99) 94%(92–96) 96% (94–97) 96% (94–98) 94% (91–96) 95%(93–97)PPV，阳性预测值 (positive predictive value) ；NPV，阴性预测值 (negative predictive value)。

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Stroke July 2010

卒中诊断的显著改善仍得以维持。

本研究的优势在于，能够对院前卒中筛查工具

在实践应用中的情况进行检验，超出了对筛查工具

本身有效性的评估。但是，本研究结果也必然存在

缺陷。首先，TIA 的最终诊断依赖于出院诊断，而

并非所有真正的 TIA 患者的出院诊断都正确。第

二，阳性及阴性预测值的评价受患病率的影响。因

为仅有 23% 的有 MASS 记录的患者诊断为卒中或

TIA，所以这些数据可能并不影响真实的评价。最后，

MASS 可能只在急救人员强烈怀疑其为卒中者中进

行，因排除了部分假阳性数据，就造成了对筛查工

具特异性的人为夸大，这也可以解释为何本研究结

果相较于之前报道 CPSS 的效用得到明显改善 [9,10]。

另一个与近期发表结果不一致的方面 [9,10] 为卒

中院前诊断率的显著提高。此差异可能是由于样本

范围不同造成，过去的研究只对院前诊断为卒中或

卒中筛查阳性的患者进行检验，而本研究将范围扩

大到所有有 MASS 记录 ( 包括阳性和阴性结果 ) 的患者。另一个原因可能由于院前急救人员的培训在

澳大利亚与美国之间有所不同，这也可用以解释筛

查工具的使用率的差异。

近期 Frendl 等报道了 CPSS 在院前卒中患者中

使用不佳 ( 仅为 37.5%)，且院前诊断率在培训后无

明显改善 [10]。但在本次研究中，MASS 的使用度很

高 ( 在有意识的神经功能缺损患者中达 85%，在卒

中患者中高达 96%)。经 MASS 评价的多数患者均存

在神经系统症状，并有无法解释的跌倒。正如之前

报道中讨论所得 [11]，我们将一部分成功原因归功于

良好的回馈系统。在接受培训后的前 18 个月内，我

们将患者接受溶栓治疗的结果提供给急救人员，这

使我们有机会提醒他们进行 MASS 评估，并向其反

馈他们的努力给患者带来的益处。

之前的研究曾显示卒中的院前诊断可缩短入院

时间 [12]，并且利用筛查工具改善卒中院前诊断与溶

栓率的提高有关，可使溶栓率升高至 21%[13]，在本

院联合使用 MASS 和入院卒中急救系统后，溶栓率

从 5%[8] 提高至 11%[14]。

综上所述，此项大样本研究显示 MASS 与院前

诊断相结合，可成功地应用于对神经功能缺损的患

者评估。MASS 在全市范围内应用三年后，卒中的

院前诊断仍保持高水平。卒中院前诊断的敏感性较

MASS 高，提示卒中的培训项目很成功。

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