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Three Part Question

In [patients with an acute sore throat] does [the addition of a throat swab or rapid antigen testing to clinical examination alone] result in [reduced inappropriate antibiotic use]?

Clinical Scenario

An 18 year old presents to A&E with a sore throat, fever, tonsillar exudates and anterior cervical lymphadenopathy and no history of a cough. She is prescribed antibiotics but should she be investigated further?

Search Strategy

Medline 1966 to June Week 1 2005
Embase 1980 to 2005 Week 24
Cinahl Cumulative Index to Nursing & Allied Health Literature
The Cochrane Library Issue 2 2005
{Exp PHARYNGITIS/ OR exp LARYNGITIS/ OR exp TONSILLITIS/ OR exp Peritonsillar Abscess/ OR pharyngitis.af. OR laryngitis.af. OR tonsillitis.af. OR (peritonsillar adj5 abscess).af. OR quinsy.af. OR (throat adj5 infection$) OR (sore adj5 throat$) OR exp Infectious Mononucleosis/ OR (infectious adj5 mononucleosis).af. OR (glandular adj5 fever).af.}AND {Streptococcus pyogenes/ Or Streptococcal Infections/ OR throat swab.mp. OR Bacteriological Techniques/ OR (throat adj5 swab).af. OR nasopharyngeal swab.mp. OR ear nose throat swab.mp. OR pharyngeal swab OR bacterial infections.mp. OR Bacterial Infections/ OR "Sensitivity and Specificity"/ OR rapid antigen testing.mp. OR bacteriology.mp. or BACTERIOLOGY/ OR microbiology.mp. OR MICROBIOLOGY/} AND {physical examination.mp. OR Physical Examination/ OR otolaryngology.mp. OR OTOLARYNGOLOGY/ OR ear nose throat examination.mp. OR ENT exam$.mp. OR oropharyngeal exam$.mp. OR throat exam$.mp.OR centor score} limit to (humans and english language)

Search Outcome

Medline 65 papers found, 5 relevant
Embase 76 papers found, no extra relevant
Cinahl 12 papers found, no extra relevant
Cochrane - none relevant

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Rose E A, Deshikachar A M, Schwartz K L et al Jul-Aug 2001 USA	50 patients who presented with a sore throat between to a family practice. Those with more complex problems were excluded. A new template was introduced which advised the following: if low likelihood of GABHS-symptomatic treatment moderate likelihood-perform a strep test and treat accordingly high likelihood-empirical treatment with antibiotics A control group was taken from visits for pharyngitis in the 6 months before the study was undertaken, this was converted from the previous notes to the template by auditors.	diagnostic study	Antibiotics not indicated but given	For patients with a moderate probability of GABHS: template used: 44% v 54% without.(not signif p=0.319) Low probability of GABHS 10% v 71% (p less than 0.05)	The small sample size makes generalizations very difficult. The auditors converting the previous notes to the template would have been subjective and had to 'fit' the notes into the template.
			Antibiotics indicated but not given	For patients with a high prob of GABHS. using template: 10% v 0% .Moderate prob 0% v 0%
Diaz MC, Symons N, Ramundo M et al Oct 2004 USA	All patients who came to the Emergency department with pharyngitis were identified and a random sample of 300 patients were chosen. Of these 219 met the study criteria and were included. An evidence based guideline was developed and implemented which advised that if there was a high suspicion of GABHS, both a rapid strep test and throat culture should be performed. 224 patients were included in the post intervention group.	controlled clinical trial	% of patients receiving appropriate treatment pre and post intervention	44% pre vs 91% post intervention	This study had no patient follow up to assess how effective the treatment had been for the patient. The data was not analysed in depth with no p values to assess significance of the findings.
			choice of antibiotics for positive RST result	pre 37.5% penicillin vs 70.8% post. pre 55% given amoxicillin vs 10% post. pre 6% given azithromycin(because allergic to penicillin) vs 0% post. The remaining 16% post were given a macrolide or clindamycin owing to penicllin allergy. 1 patient was give amoxicillin and clavulanate.
McIsaac WJ, Butler CC 2000 Canada	584 patients over 3 years old presenting with Upper Respiratory Infections. Physicians completed a standardized clinical assessment and took a single throat swab from each patient. They also noted whether an antibiotic was prescribed and what they believed the likelihood of GABHS infection was. The gold standard was throat culture	diagnostic study.	unnecessary antibiotics prescribed	70/105 (66.7%)	45% participation rate out of eligible candidates, but there was no difference between the age-sex distributions of those who participated and those who didn't.
Mainous AG, Zoorob RG, Kohrs FP et al sept 1996 USA	Children over 3 years and less than 18 years in. 3478 individuals seen on 5067 separate occasions in an ambulatory setting, outpatient or emergency room, with a diagnosis of tonsillopharyngitis, over 1 year.	survey	% of antibiotic use in encounters without a diagnostic test performed vs encounters with a test perfomed	73% vs 68% P=0.001	The study concludes that antibiotics were prescribed by analysing if a prescription was given by seeing whether antibiotics were recieved within 5 days. Some sore throat visits were coded tonsillopharyngitis and some streptococcal sore throat. Diagnostic testing was only performed in 22% of tonsillophayngitis diagnoses and 36% of the streptococcal sore throat encounters.
			As above in encounters coded as streptococcal sore throat	67% vs 69% p=0.49
McIsaac WJ, Kellner JD, Aufricht P et al 2004 Canada	787 children and adults presenting with acute sore throat. Recommendations from 2 guidelines were compared with rapid testing alone, a clinical prediction rule (the modified Centor's score) and treatment for positive throat cultures only. Culture all was the gold standard	diagnostic study	Culture all	inappropriate antibiotic prescription 0%	this study only included adults and children with a modified Centor score of 2 or more, however most guidelines support the use of clinical scores to to exclude patients. The sensitivity of the rapid test was only 83%. The study was not able to assess the impact of higher or lower GABHS prevalence.
			Children-rapid test all, treat those with positive results, throat culture those with negative strep tests. Adults rapid test all, treat positive results, dont culture negative results	0.6%
			children-treat as above. Adults rapid test all with a centor score of 2 or 3 and treat if positive. Treat all adults with a centor score over 4 empirically.	1.8%
			treat children as above. test no adults and treat those with a centor score of 3 or 4 empirically	18.9%
			throat culture all with a centor score of 2 or 3.If score of 4 or more treat empirically.	4.8%
			rapid test on all children and adults, treat those with positive results without culture confirmation of negative results	0.6%

Comment(s)

The Mainous study was of low quality compared to the other studies and was not very useful and because not all patients were tested the use of appropriate antibiotics couldnt be assessed. The McIsaac study was the most useful because it was able to fairly compare different strategies. It showed that unneccessary antibiotic prescription was highest in strategies which recommended empirical treatment of adults based on Centor score only and unneccessary prescription was of course lowest in throat culture for all. Of the other strategies the least prescription of inappropriate antibiotics occured when a rapid strep test was performed on all children with culture negative results: adults strep test all without culture of of negative results: and performing rapid tests on all, no culture of negative results. The latter strategy has a very low sensitivity. When recommending rapid antigen testing the accuracy of the test and the cost must be also be considered.

Clinical Bottom Line

Clinical examination and investigation result in reduced inappropriate antibiotic use compared to clinical examination alone. For adults the best strategy, taking into account specificity and sensitivity, seems to be to rapid test all without culture confirmation of negative results. For children rapid test all and then culture negative results.

References

1. Rose E A, Deshikachar A M, Schwartz K L et al Use of a Template to Improve Documentation and Coding Family Medicine Jul-Aug 2001;33(7):516-21
2. Diaz MC, Symons N, Ramundo M et al Effect of a Standardized Pharyngitis Treatment Protocol in a Pediatric Emergency Department Arch Pediatr Adolesc Med Oct 2004 158 pg 977-981
3. McIsaac WJ, Butler CC Does clinical error contribute to unnecessary antibiotic use? Med Decis Making 2000 20:33-8
4. Mainous AG, Zoorob RJ, Kohrs FP et al Streptococcal diagnostic testing and antibiotics prescribed for paediatric tonsillopharyngitis The Pediatric Infectious Diseases Journal. september 1996 pages 806-810
5. McIsaac WJ, Kellner JD, Aufricht P et al Empirical Validation of Guidelines for the management of Pharyngitis in Children and Adults JAMA apr 7 2004 vol 291, No.13 1587