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Accuracy of clinical diagnosis versus the World Health Organization case definition in the Amoy Garden SARS cohort

Published online by Cambridge University Press:  21 May 2015

W.N. Wong*
Affiliation:
United Christian Hospital Emergency Department, Hong Kong
Antonio C.H. Sek
Affiliation:
United Christian Hospital Emergency Department, Hong Kong
Rick F.L. Lau
Affiliation:
United Christian Hospital Emergency Department, Hong Kong
K.M. Li
Affiliation:
United Christian Hospital Emergency Department, Hong Kong
Joe K.S. Leung
Affiliation:
United Christian Hospital Emergency Department, Hong Kong
M.L. Tse
Affiliation:
United Christian Hospital Emergency Department, Hong Kong
Andy H.W. Ng
Affiliation:
United Christian Hospital Emergency Department, Hong Kong
Robert Stenstrom
Affiliation:
Department of Emergency Medicine, St. Paul’s Hospital, Vancouver, BC
*
Accident & Emergency Department, United Christian Hospital, Hong Kong; fax 852-26285379, wingnam@email.hkuspace.com

Abstract

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Objectives:

To compare the diagnostic accuracy of emergency department (ED) physicians with the World Health Organization (WHO) case definition in a large community-based SARS (severe acute respiratory syndrome) cohort.

Methods:

This was a cohort study of all patients from Hong Kong’s Amoy Garden complex who presented to an ED SARS screening clinic during a 2-month outbreak. Clinical findings and WHO case definition criteria were recorded, along with ED diagnoses. Final diagnoses were established independently based on relevant diagnostic tests performed after the ED visit. Emergency physician diagnostic accuracy was compared with that of the WHO SARS case definition. Sensitivity, specificity, predictive values and likelihood ratios were calculated using standard formulae.

Results:

During the study period, 818 patients presented with SARS-like symptoms, including 205 confirmed SARS, 35 undetermined SARS and 578 non-SARS. Sensitivity, specificity and accuracy were 91%, 96% and 94% for ED clinical diagnosis, versus 42%, 86% and 75% for the WHO case definition. Positive likelihood ratios (LR+) were 21.1 for physician judgement and 3.1 for the WHO criteria. Negative likelihood ratios (LR–) were 0.10 for physician judgement and 0.67 for the WHO criteria, indicating that clinician judgement was a much more powerful predictor than the WHO criteria.

Conclusions:

Physician clinical judgement was more accurate than the WHO case definition. Reliance on the WHO case definition as a SARS screening tool may lead to an unacceptable rate of misdiagnosis. The SARS case definition must be revised if it is to be used as a screening tool in emergency departments and primary care settings.

Type
EM Advances • Innovations en MU
Copyright
Copyright © Canadian Association of Emergency Physicians 2003

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