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Table of Contents
ORIGINAL ARTICLE
Year : 2020  |  Volume : 3  |  Issue : 1  |  Page : 44-47

Sensitivity and specificity of a Middle East respiratory syndrome screening tool used in the emergency department


1 Department of Emergency Medicine, King Abdulaziz Medical City, King Saud Bin Abdulaziz University for Health Sciences, Ministry of National Guards, Riyadh, KSA
2 Department of Emergency Medicine, College of Medicine, King Saud University, Riyadh, KSA

Date of Submission03-Apr-2019
Date of Decision02-Sep-2019
Date of Acceptance04-Sep-2019
Date of Web Publication06-Jan-2020

Correspondence Address:
Anas Khan
College of Medicine, King Saud University, Riyadh
KSA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JNSM.JNSM_15_19

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  Abstract 


Background: Middle East respiratory syndrome coronavirus (MERS-CoV) infection becomes a global health issue because of its ability to spread rapidly, especially in healthcare settings. Improper triage of MERS-CoV-infected patients in the emergency department (ED) increases the risk of infection in healthcare providers and other patients. Having a good triage screening tool would improve early detection and isolation of suspected infected patients, thus preventing future outbreaks. Materials and Methods: This is a retrospective cohort study performed in a large urban, academic ED in a tertiary care center in Riyadh, Saudi Arabia. The aim of the study was to assess the accuracy of the triage screening tool used in the ED. A convenience sample of 734 patients visiting the ED during the 2015 MERS-CoV outbreak was included. Patients deemed positive were isolated and underwent MERS-CoV polymerase chain reaction (PCR) testing. Patients deemed negative were followed up via phone after two weeks of their ED visit. They were checked for the development of symptoms and whether the patients sought medical advice in another hospital or underwent MERS-CoV PCR testing. Results: The sensitivity of the screening tool for detecting PCR-positive MERS-CoV infection was 100% (95% confidence interval [CI]: 15.8–100), and the specificity was 78.2% (95% CI: 75.1–81.2). Conclusions: The ED triage screening tool used during the 2015 MERS-CoV outbreak is highly sensitive. It is effective for early detection of infection in the ED, thus allowing timely isolation of suspected patients.

Keywords: Emergency, Middle East respiratory syndrome, screening


How to cite this article:
Alsolamy S, Khan A, Yousef S, Alghusen F, Alsalman A, Alnaim A, Alsalamah M, Alassim N, Alenazi T, Aljerian N, Alaska Y. Sensitivity and specificity of a Middle East respiratory syndrome screening tool used in the emergency department. J Nat Sci Med 2020;3:44-7

How to cite this URL:
Alsolamy S, Khan A, Yousef S, Alghusen F, Alsalman A, Alnaim A, Alsalamah M, Alassim N, Alenazi T, Aljerian N, Alaska Y. Sensitivity and specificity of a Middle East respiratory syndrome screening tool used in the emergency department. J Nat Sci Med [serial online] 2020 [cited 2020 Jan 21];3:44-7. Available from: http://www.jnsmonline.org/text.asp?2020/3/1/44/275168




  Introduction Top


Middle East respiratory syndrome coronavirus (MERS-CoV) infection becomes a major global health issue, following the isolation of the virus in Saudi Arabia in 2012.[1] As of the end of September 2018, the World Health Organization (WHO) has reported 2260 laboratory-confirmed cases of MERS-CoV infection and at least 803 related deaths in 27 countries worldwide.[2]

The MERS-CoV is a single-stranded RNA virus with a high mutation rate.[3] It is thought to be a zoonotic virus that crossed the species barrier to humans and has been strongly linked to camels in the Arabian Peninsula.[4] The median incubation period for MERS-CoV infection is 5.2 days; incubation can be as long as 12 days.[5]

Despite its low transmissibility in the community, the MERS-CoV spreads very rapidly in healthcare facilities, a characteristic shared by the severe acute respiratory syndrome coronavirus (SARS-CoV).[6],[7],[8],[9],[10],[11] Hospital outbreaks since 2012 have confirmed that person-to-person transmission occurs, especially in healthcare facilities.[5],[6],[7],[11],[12],[13],[14] Improper triage of MERS-CoV-infected patients increases the risk of infection in healthcare providers and other patients, particularly if aerosol-generating procedures are not performed in a negative pressure room using airborne precautions.[15]

The virulence of the MERS-CoV and its rapid spread in healthcare facilities highlights the need for early identification of infected patients during emergency department (ED) triage. At present, screening tools that quickly deliver reliable results are lacking. Early identification will ensure isolation of suspected patients and the proper use of personal protective equipment, hence preventing unprotected exposures and MERS-CoV transmission.[16],[17],[18],[19] Symptom-based screening approaches are very useful in healthcare facilities and helped to control the SARS outbreak in 2003.[20]

This study aimed to evaluate the performance of an ED triage screening tool for MERS-CoV infection that was developed and used at our institution during the nosocomial MERS-CoV outbreak in 2015.


  Materials and Methods Top


Study area and setting

This is a retrospective cohort study performed in a large urban, academic ED in a 900-bed tertiary care center in Riyadh, Saudi Arabia. It was conducted during the MERS-CoV outbreak in August–October 2015 and approved by the institutional Research Ethics Board. The ED is staffed by board-certified emergency medicine physicians and has 15 resuscitation beds for high-acuity patients and 49 beds for moderate-acuity patients. There are approximately 200,000–214,000 ED visits to our center per year.

Data collection and processing

A convenience sample of 734 patients visiting the ED during the 2015 MERS-CoV outbreak was screened using the ED triage screening tool. The tool was developed during the outbreak and was based on the WHO and Saudi Ministry of Health case definitions, as well as the expertise of the Emergency and Infectious Control Departments.[21],[22]

The ED triage screening tool was designed to ensure the early detection and hence the isolation and proper handling of MERS-CoV-infected patients [Figure 1]. This tool was meant as a complementary, not a replacement, to the emergency triaging for acuity. Thus, creating two tracks to separate the patients with respiratory symptoms from non-respiratory symptoms. The screening tool consists of three parts: Part 1 focuses on fever (two questions), Part 2 on respiratory symptoms within the past 14 days (four questions), and Part 3 on contact history (three questions). A patient is deemed positive (i.e., suspected of MERS-CoV infection) if he or she answers yes to at least one question in each of two parts. A patient is deemed negative if he or she answered no to all questions or even if he or she answered yes to more than one question on a single part of the screening tool.
Figure 1: Middle East respiratory syndrome emergency department respiratory triage screening form and follow form

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The questions were asked by trained triage nurses, and the screening form was filled in by the nurse accordingly. Patients deemed positive were placed under respiratory airborne isolation precautions and then examined by an ED physician to determine whether they fulfilled the WHO definition of MERS-CoV infection. Only those who had underwent MERS-CoV polymerase chain reaction (PCR) testing. Patients deemed negative were followed up via phone no sooner than 2 weeks after their ED visit. The follow-ups were conducted by trained quality coordinators using a standardized form. Their purpose was to check for the development of symptoms and to determine whether the patients sought medical advice in another hospital or underwent MERS-CoV PCR testing within 14 days after their ED visit. Patients who sought medical advice and underwent PCR testing were considered suspect, and study investigators tracked their PCR results.

Data analysis

The accuracy of the ED triage screening tool was measured by comparing its results to those of the MERS-CoV PCR test, which is the gold standard for diagnosis of MERS-CoV infection. The following performance characteristics were determined: sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio, with corresponding 95% confidence intervals (CIs). Statistical analysis was performed using the SPSS 20.0 Software Package (SPSS Inc., Chicago, IL, USA).


  Results Top


Characteristics of the study subjects

A total of 734 patients were screened for MERS-CoV infection in the ED using the ED triage screening tool. The clinical characteristics of the patients (n = 161) with suspected MERS-CoV infection in the ED are presented in [Table 1]. Only two of these patients had positive MERS-CoV PCR test results. For patients with negative screening results in the ED (n = 573), the median time between initial screening and follow-up was 25 (range 14–51) days. Among these patients, only 19 developed respiratory symptoms and met case definition and none had positive MERS-CoV PCR test results.
Table 1: Baseline characteristics of patients with positive results in the emergency department triage screening test (n=161)

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Main results

The performance characteristics of the ED triage screening tool are shown in [Table 2]. The sensitivity of the screening tool for detecting PCR-positive MERS-CoV infection was 100% (95% CI: 15.8–100), and the specificity was 78.2% (95% CI: 75.1–81.2).
Table 2: Performance characteristics of the emergency department triage Middle East respiratory syndrome screening tool

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  Discussion Top


MERS-CoV infection causes severe pulmonary diseases with multiorgan involvement and has a high fatality rate. The absence of tests that rapidly provide reliable results, and hence expedite early detection of MERS-CoV infection, may contribute to unprotected exposures, delayed isolations, and consequent hospital outbreaks.

The ED triage screening tool described herein was used to screen patients presenting to the ED during the MERS-CoV outbreak in 2015. Its high sensitivity supports its use as an accurate and convenient identifier of potentially infected patients, allowing their isolation before full evaluation by physicians. Because it is easy to use, as ideally screening tools should be,[23] ED triage nurses can rapidly screen incoming patients to identify those who require isolation without delaying the clinical care of other patients. This tool helped to control the MERS-CoV outbreak in 2015 by preventing unprotected exposures and disease transmission.

The ED triage screening tool had a high negative predictive value and low positive predictive value. Hence, the probability of isolating noninfectious patients, which can adversely affect them physically and psychologically, is high. This problem arose when a similar screening tool was used during the H1N1 influenza season: 67% of the patients without influenza were unnecessarily placed in respiratory isolation.[24] A low positive predictive value may reflect the low prevalence of the disease; therefore, prospective studies of more prevalent diseases are needed to better assess the performance of the screening tool.


  Conclusions Top


The ED triage screening tool for MERS-CoV infection is highly sensitive. It is effective for early detection of infection in the ED, thus allowing timely isolation of suspected patients.

Limitations

First, not all patients who underwent ED screening also underwent MERS-CoV PCR testing. This was because of cost prohibitions and because PCR testing was not justified (i.e., the ED physician's assessment did not meet the case definition for MERS-CoV infection). For those who screened negative in the ED and did not fulfill the case definition, a phone follow-up served as an alternative reference standard in this study. Second, there was a relatively long time interval between the ED screening and the follow-up in some patients owing to the inability to reach these patients by phone at scheduled times. Third, other respiratory infections may have similar clinical presentations as MERS-CoV infection that may affect the accuracy of the screening tool (such as H1N1 influenza). Finally, this was a retrospective study, and it will be stronger to have a randomized screening for presenting patients to exclude asymptomatic carriers.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Ministry of Health-Saudi Arabia. Case Definition and Surveillance Guidance. Ministry of Health-Saudi Arabia; June, 2015. Available from: https://www.moh.gov.sa/CCC/healthp/regulations/Documents/MERS-CoV%20Guidelines%20for%20Healthcare%20Professionals%20-%20May%202018%20-%20v5.1%20%281%29.pdf. [Last accessed on 2019 Sep 22].  Back to cited text no. 22
    
23.
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Mulpuru S, Roth VR, Lawrence N, Forster AJ. Influenza infection screening tools fail to accurately predict influenza status for patients during pandemic H1N1 influenza season. Can Respir J 2013;20:e55-9.  Back to cited text no. 24
    


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