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
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 (50- 80% 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: GABHS sore throat
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 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.
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.
1.1.1.1 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 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.
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.
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.
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.
1.1.1.2 Do antibiotics improve symptoms and reduce the risk of complications?
A large UK primary care study from 2018 found that sore throat is the condition associated with the highest frequency of inappropriate antibiotic prescribing. 24 A 2021 Cochrane review examining the effects of antibiotics for sore throat (from any aetiology) included 29 trials and 15,337 adults and children with sore throat. The systematic review found that antibiotics provided a modest reduction in the risk of being symptomatic with sore throat (along with headache) and also of developing suppurative and non-suppurative complications. 25 In terms of symptom reduction, the number needed to prevent one sore throat was <6 at day three (but 3.7 for those with GABHS on throat swab) and increased to 18 overall at day seven. They reported that 82% of patients in the control groups are symptom-free by one week (without antibiotic treatment). The authors commented that the number needed to treat for a beneficial outcome might be lower in low-income countries, or in socioeconomically deprived areas of high-income countries, where complications such as acute rheumatic fever are more widespread. There are obvious drawbacks of prescribing antibiotics; antimicrobial resistance, side effects of the medication (including allergy), costs. Another unwanted outcome is that the usually self-limiting presentation of sore throat becomes ‘medicalised’, resulting in increasing presentation to the GP for future episodes. 26
International guidelines for management of sore throat
Many countries have their own guidelines for the treatment of sore throat, some of which with their most up to date recommendations are summarised below.
The Health Service Executive (HSE) in Ireland issues guidelines in relation to antibiotic prescribing for sore throat. 27 The advice does not mention using throat swab for diagnosis. They advise that most people with sore throat do not benefit from antibiotics and recommend using the FeverPAIN scoring system to aid decisions about antibiotic prescribing. 28 First line recommended antibiotic is phenoxymethylpenicillin 666mg (or 500mg) 4 times daily for 5 days.
The National Institute for Health and Care Excellence (NICE) in the UK and Scottish Intercollegiate Guidelines Network (SIGN) in Scotland have similar guidelines in relation to the management of sore throat. 29,30 Both recommend against the use of throat swab. Both recommend using the FeverPAIN or Centor score CPR. The NICE guidelines recommend not to offer an antibiotic at Centor score levels of 0,1 or 2, and to consider an antibiotic at levels 3 or 4. The SIGN guidelines recommend not to use antibiotics for sore throat but that ‘antibiotics should not be withheld’ in severe cases. First line recommended antibiotic is the NICE guideline is phenoxymethylpenicillin 500mg 4 times a day or 1000mg twice a day for 5 to 10 days and in the SIGN, guideline is phenoxymethylpenicillin 500mg 4 times a day for 10 days.
European Society for Clinical Microbiology and Infectious Diseases (ESCMID) guidelines from 2012 suggest using rapid antigen testing if Centor score is 3-4 but advises that the clinical utility of the Centor score is lower in children because of the differing presentations of sore throat in the early years of life. 31
A set of 2001 guidelines from the USA (recommended by the American Academy of Family Physicians (AAFP), the American College of Physicians–American Society of Internal Medicine (ACP- ASIM) and Center for Disease Control (CDC)), recommend combining the Centor score CPR with rapid antigen testing to guide diagnosis. 18
Duration of antibiotic therapy
A study from 2019 found that Penicillin V four times daily for five days was non-inferior in clinical outcomes to penicillin V three times daily for ten days, in patients with GABHS sore throat. 32 There is no Cochrane review on this topic in adults, although the equivalent review focussing on children under 18 with GABHS sore throat found that shorter courses of oral antibiotics (3-6 days) had comparable efficacy compared to the standard 10-day course of oral penicillin. 33 Current sore throat guidelines from Ireland recommend a 5 day course of antibiotics, and the UK guidelines recommend a 5-10 days course of antibiotics, when they are indicated. Many of the international guidelines have not been updated to reflect this recent research.
A summary of some of the most recent guidelines is presented in Table 2.
The surprising differences between guidelines (which should be based on the same underpinning best evidence) has been the case with clinical guidelines for other conditions also. Explanations given for the variations have included insufficient evidence, different interpretation of the evidence, unsystematic guideline development, influence of professional societies, patient preferences, cultural factors and societal factors. 34 The WHO has recommended a systematic process incorporating nineteen key components to ensure that clinical guidelines are based on best available evidence. 35
Corticosteroids for sore throat
A BMJ ‘rapid recommendation’ article from 2017 gave a weak recommendation to use a single dose of oral steroids in cases of acute viral or bacterial sore throat, regardless of severity, for patients aged five and older (excluding those patients in whom IM is suspected or immunocompromised patients, as these were not included in the systematic review on which the recommendation was based). 36 The systematic review of the available evidence included a RCT published in April 2017, which included over 500 primary care patients. 37,38 The recommendation was stated as ‘weak’ because of the modest reduction in patients symptoms (intensity and duration of sore throat), and because of variability in patient preferences; shared decision-making is recommended.
Conclusion
The literature demonstrates that there is a direct link between attendance rates for primary care physicians and antibiotic prescribing, and that the threshold to interact with a GP is lowered by telemedicine. 39-41 With the advent of the Covid-19 pandemic, increasing use of telemedicine, and huge pressures on all aspects of the health service, clinicians should be mindful of the risks of overprescribing of antibiotics.
In terms of guidelines for the diagnosis and management of sore throat, and in light of increasing antimicrobial resistance, it seems prudent to adopt the guidelines of the HSE, NICE and SIGN, incorporating a CPR (rather than throat swab or RADT) to aid in diagnosis, and reduce antibiotic prescribing. It is likely that most patients would benefit more from sensible self-management advice, with safety netting systems in place in case of deterioration. The literature demonstrates that antibiotics are of minimal benefit in sore throat, even when GABHS is present. 25
References available on request
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