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Sore Throat
Sore Throat Management in Pharmacy Sore throat is a common presenting symptom in primary care. A systematic review from 2019, including data from primary care patients across twelve countries, found that sore throat was the fourth most common reason for presentation.1 It is a symptom that disproportionately affects children and younger adults, with incidence declining from the age of forty onwards.2 Written by Dr Muireann de Paor Specialist Registrar in Public Health Medicine Muireann de Paor graduated from Medicine in UCC in 2005 and completed GP vocational training in 2011. She has worked in clinical and academic general practice up to recently, and has now started specialist training in Public Health.
Sore throat can be caused by a number of pathogens; viral (5080% of cases), bacterial (10-20%), or fungal (<1% of cases), and from non-infectious causes e.g., gastroesophageal reflux disease or allergic rhinitis.3-5 The patient’s history can help differentiate infectious from non-infectious causes, and the patient’s age is an important aspect of this. However, the causative pathogens of cases of acute sore throat can be difficult to distinguish clinically. Viral causes (e.g. rhinovirus, adenovirus, coronavirus, EBV) can often be associated with other features of an upper respiratory tract infection (URTI) e.g. cough, coryza and fatigue.6 Clinical condition: sore throat caused by Group A Beta Haemolytic Streptococcus (GABHS) GABHS is the most common bacterial cause of acute sore throat, estimated to cause approximately 5-15% of adult cases of sore throat in developed countries, and higher rates in less developed countries.7 A systematic review from 2000 found rates of between 10-36% of GABHS in adults and children presenting with sore throat.8 Clinical Features A systematic review of nine studies concluded that the most predictive signs and symptoms of GABHS were: presence of tonsillar or pharyngeal exudate, exposure to GABHS infection in
the previous two weeks, history of fever, and the absence of tender anterior cervical nodes, absence of tonsillar enlargement, or exudate, and absence of cough.8 No single symptom or sign was deemed predictive enough to rule in or rule out GABHS sore throat on its own. GABHS sore throat is usually a self-limiting condition; and generally resolves spontaneously (even without antibiotic intervention) by about 7-10 days.8 However, complications can rarely include sinusitis, otitis media, peritonsillar abscess, rheumatic fever and glomerulonephritis. GABHS carrier state Asymptomatic carriage of GABHS is frequent, especially in children. A 2018 systematic review which examined rates of GABHS carriage found a rate of 2.8% of carriage in adults (based on 12 included studies), and 8.0% in children (based on 46 included studies).9 Because of the overlap of symptoms, patients with acute viral sore throat who have a positive throat swab for GABHS may just be carriers of GABHS and receive antibiotics inappropriately. Diagnosis and management Clinical prediction rules ‘Clinical prediction rules’ (CPRs) or ‘clinical decision rules’ are clinical tools that calculate the independent influence of factors from a patient’s history, clinical examination and diagnostic tests, and stratify patients according
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to the probability of having the disorder of interest.10 CPRs are progressively more being used to aid in the diagnostic process and subsequent clinical management decisions.11 They are often used to help clinicians refine their diagnosis or to ‘rule in’ or ‘rule out’ certain conditions depending on the setting in which they are used and the condition they are used for.12 In primary care they are particularly helpful in ruling out conditions of interest or when adopting an expectant approach to management.
from acute infection.18,19 Another disadvantage of the throat swab is that it typically takes more than 24 hours, and often takes several days to obtain the result.
A variety of clinical prediction rules (CPRs) exist to aid in the diagnosis and management of GABHS sore throat, the originally CPR being the Centor score.13 The four elements of the Centor Criteria are tonsillar exudate, anterior cervical lymphadenopathy, fever, and absence of cough. A variation of the Centor score which was developed in the UK in a larger derivation cohort and was deemed to perform better at identifying people at low risk of diagnosis of streptococcus is the FeverPAIN score.14 The FeverPAIN score uses the five variables: fever in past 24 hours, absence of cough or coryza, symptom onset ≤3 days, purulent tonsils and severe tonsil inflammation. The FeverPAIN score can be used for diagnosis of group A, C or G GABHS infection.
Rapid antigen detection testing (RADT) for GABHS is used in some clinical settings and is currently used more frequently in the USA than in the UK and Ireland. These tests provide a quick indication to the clinician about the presence of GABHS, usually giving a result within 15 minutes. In symptomatic people, they have a sensitivity of approximately 85% and a specificity of 95%, which may make them more appropriate for use as a ‘rule in’ test.20,21 However, they cannot provide information about any other potential bacterial causes of sore throat, which may be identified on the result of a throat swab culture. A recent study piloting pharmacists’ use of RADT to test and treat GABHS in Wales resulted in a small reduction in prescriptions for phenoxymethylpenicillin.22 This was based on 1725 consultations in 56 pharmacies. The pharmacists used a minimum Centor score of 2 or a FeverPAIN score of 1 to offer RADT. Using RADT for diagnosis, 28.2% of participants had positive tests for GABHS and 27.4% of participants were supplied with antibiotics.
Question 1: Does a throat swab improve diagnostic accuracy for GABHS? Most international guidelines do not currently recommend throat swab for diagnosis of GABHS sore throat. However, for research and occasional diagnostic purposes, the reference standard for diagnosis of GABHS is by throat swab culture, despite several issues.15 This test has a sensitivity of approximately 90%,according to studies that used duplicate throat culture testing.16 Other advantages are its low cost, acceptability to patients, and the fact that the culture can identify other causative pathogens and guide antibiotic sensitivities.17 However, throat swab culture results can be controversial, as it cannot distinguish carrier state
Point of care tests (POCT) / near patient tests / rapid antigen tests are tests (blood / urine / swab) that are performed during a patient’s consultation. They are generally used to detect the presence of a pathogen or an inflammatory marker and they are used as clinical decision aids in some settings.
The gold standard reference test for GABHS is considered to be serial serum sampling for antistreptococcal antibodies; namely antistreptolysin O titre (ASOT) and antideoxyribonuclease B (ADNaseB). The combination of these two antibodies gives results for GABHS at a sensitivity of 96% and specificity of 89%.23 However, this is rarely used in practice due to cost, delay and inconvenience for patients and clinicians.
