Publications
Use of
Both a Clinical Score and Rapid Antigen Test Improves the Bedside Diagnostic
Accuracy to Detect Group A Streptococcus (GAS) Sore Throats.
J. D. KELLNER1, P. AUFRICHT2, W. J. MCISAAC3,
L. BUCHOLTZ2, A. VANJAKA4, D. E. LOW3;
1Univ. of Calgary, Calgary, AB, Canada, 2Crowfoot
Village Fam. Prac., Calgary, AB, Canada, 3Mt. Sinai Hosp.
& Univ. of Toronto, Toronto, ON, Canada, 4Abbott Laboratories,
Montreal, PQ, Canada.
Background:
Treatment of GAS tonsillitis can be deferred pending throat culture
results but there are often compelling reasons to decide on treatment
at the initial clinical encounter. Our objectives were to further
validate the McIsaac Sore Throat Score (MSTS) and evaluate the combined
use of the MSTS and a rapid antigen test.
Methods:
Persons with acute sore throats presenting to a large family practice
clinic in Calgary were screened with the MSTS and TestPack +Plus®
ELISA rapid test. The MSTS has 4 items (temp >38º C, absence of cough,
tender cervical nodes and tonsillar swelling or exudate) and an age
modifier. A score of 0 to 4 is possible. The likelihood of GAS is
<5% for scores of 0 and 1. For scores of 2, 3 & 4, the likelihood
of GAS is 11%, 28% & 53%, respectively (CMAJ 1998;158:75). A throat
culture for GAS was performed in all cases.
Results:
There were 757 patients with MSTS of >1 who were screened. A positive
culture for GAS was found in 16%, 28% and 63% of those with MSTS of
2, 3 and 4, respectively.
|
Age
|
GAS
Culture
|
Rapid
Test Predictive Value
|
|
Positive
|
Negative
|
Sens
|
Spec
|
PV+
|
PV-
|
|
3
- 14 yrs
|
142
(40%)
|
213
(60%)
|
87%
|
99%
|
98%
|
92%
|
|
>
14 yrs
|
74
(19%)
|
328
(81%)
|
76%
|
99%
|
97%
|
95%
|
|
All
ages
|
216
(29%)
|
538
(71%)
|
83%
|
99%
|
97%
|
94%
|
Sens
= sensitivity, Spec = specificity, PV+ = positive predictive value,
PV- = negative predictive value
Conclusions:
1)
This study further validates the predictive value of the MSTS. 2)
In patients with acute sore throat and a clinical score indicating
intermediate or high likelihood of GAS (MSTS >1), performing a rapid
test can accurately identify most true GAS cases at the initial visit
and reduce the number of throat cultures required. This strategy would
be useful in some settings.
42nd INTERSCIENCE CONFERENCE ON ANTIMICROBIAL AGENTS AND CHEMOTHERAPY
(ICAAC), San Diego, California, USA, September 27, 2002. 11:00am-12:30pm
©Copyright 2002 Last Modified
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