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The management of sore throats is a rapidly changing subject. This tutorial has been updated to include recent evidence regarding the benefits versus dangers of treating sore throats with anticiotics. The previous tutorial written in 1997 is included for comparison and because I feel it is still relevant. The update can be accessed by clicking on the 1999 update.

Francisco Machado 1999

Title: Management of sore throats 1997

Incidence:

• 600 URTIs are seen by a GP per year
• 100-150 sore throats

Micro Throat swab culture form patients with a sore throat yield:

• 40% no growth
• 30% grow a beta-haemolytic streptococcus
• 20% grow a virus
• other less common include, candida, pneumococcus and haemophilus

Streptococcus are isolated in 50% of children aged 4-13 years

Making the diagnosis

Clinical

McWhinney

The clinical cluster of sore throat, temp. > 38 C, enlarged cervical LNs, pharyngeal exudate and the absence of cough has a predictive value of 25% and a negative predictive value of 95%

Lab tests

1. Throat swab
Main limitation is that it is not able to differentiate between infection and carriage , (10%) in some populations. Up to 80% of patients receive an antibiotic without a throat swab being taken.

Arguments against swabbing
1. Time delay of 24-48hrs leading to treatment delay
2. Cost of approximately £2-4 per test
3. Swabbing the throat is unpleasant

2. Rapid antigen test
Use agglutination and enzyme immunoassay to detect streptococcal antigen on a throat swab. Each test costs £4 and gives a result in minutes. Sensitivity varies but may be as high as 90%

3. Measurement of C-reactive protein in surgery.
Kits cost £2 per sample.
CRP higher in bacterial throats.

4. Anti-streptolysin O titre (ASO) measurement
Too late to alter the management of an acute sore throat

Why treat?

Historically the main differential diagnosis was between streptococcal and diphtheria
infection. Now it is between strept an viral infections. Both are self limiting therefore why
treat.

1.To relieve symptoms
Streptococcal sore throats are self limiting.
However symptoms resolve more quickly if penicillin is given by 24-48hs, therefore
reducing time spent away from school and work. Differing results with different groups

2. Eradication of infection
10 day course of penicillin eradicates S.pyogenes in most patients. Without treatment eradication may take up to 4 months

3. To prevent complications
Suppurative complications e.g. quinsy are rare whether the patient is treated. The incidence has declined prior to the introduction of penicillin
Acute rheumatic fever is rare in industrialised countries because

1. Improvements in general living condition
2. Herd immunity
3. Use of penicillin
4. A change in the pathogenicity of the organism

NB there has been a resurgence of rheumatic fever in the USA

Social "pressure" to prescribe

When to treat or swab

McWhinney based on the predictive values of different clinical symptoms and signs suggests the following strategy

1. Adult c/o sore throat, but no exudate, no cervical LNs, and temp<38C  No throat swab, no antibiotic
2. Adult c/o sore throat, no cough, but presence of cervical LNs, exudate and temp>38C Prescribe antibiotic but no throat swab
3. Adults with a clinical picture in between  Throat swab and treat on the basis of result
4. Children with a high probability of strept sore throat prescribe an antibiotic.

Which antibiotic?

1st line Penicillin or erythromycin if pen allergy(NB overall resistance of Streptococcal pyogenes to macrolides is 20%)

2nd line Recurrence or failure of treatment e.g. cephalosporins or co-amoxyclav. Amoxycillin may be more palatable in children.

Problems with treating

1. Potential side effects
2. Cost to the NHS
3. Encourages drug resistance esp Staph
4. Colludes and foster a dependent sick role.

1999 Update.

Giving antibiotics for sore throats results in higher rates of reattendance for recurrent symptoms. This was demonstrated by Little et al in a randomised trial of three approaches to the management of sore throat in patients > 4 years in  11 GP practices in England.

The three approaches were:

• 10 days penicillin on presentation
• no antibiotics
• a prescription for 10 days penicillin to be collected in three days if symptoms did not resolve.

Outcomes included:

• early return within 2 weeks
• otitis media, sinusitis, quinsy
• reattendance within a year

Findings

The authors group the results into two main groups

1. immeadiate antibiotics
2. delayed and no antibiotics

They found that:

• there was a low complication rate in both groups approx 0.8 and there was no significant difference between the two
• there was no difference in "early returns" between the two groups
• there was an increased representation with symptoms of an URTI in patients who were immeadiately given antibiotics than  in the other group which was exacerbated by previous attendance prior to the trial.

The authors therefore suggest that immeadiate prescription of antibiotics is not necessary with regard to complications and increases future workload.

However by grouping the patients who had delayed and no antibiotics they have still not answered the question about whether we should give antibiotics at all. In fact the lowest rates of reattendance presented by the authors was for delayed antibiotics!!

Reference

P Little, C Gould, I Williamson, G Warner,  M Gantley,  A L Kinmonth. Reattendance and complications in a randomised trial of prescribing strategies for sore throat: the medicalising effect of prescribing antibiotics . BMJ 1997;315:350-352

Graham and Fahey's Evidence Based Case Report on Sore throat

Summary.

• Throat swabs have low sensitivity, true positives  (26-30%), better specificity, true negatives (73-80%) when compared to a rise on ASOT for an acute strept A sore throat.
• There is a low preedicitve value (figure not given) due to high carriage rate. However if you do a throat swab and a strep is found it "is difficult not to treat it".
• Cohrane report suggests that 90% of all treated and untreated patients will be better within one week but dose treated have greater symptom relief by day three
• rate of quinsy in GP is low
• rheumatic fever rates are low, but older trials (1950s) did indicaate that treating exudative tonsillitis did reduce incidence of rheumatic fever
• risks include side effects, possible medicalising of illness and ? earrly recurrence

Authors suggest:

• "only very ill are likely to benefit from treatment"
• For the rest advanatges are at best marginal.
• Patients need consistent advice.

Ref.

Graham, A., Fahey, T. (1999). Evidence based case report: Sore throat: diagnostic and therapeutic dilemmas. BMJ 319: 173-174.

Francisco Machado 6/1/1997