Tonsillitis is an infection of the mucosa and parenchyma of the tonsils. The most common causative micro-organisms of an uncomplicated tonsillitis are viruses (e.g. coxsackievirus, respiratory syncytial virus) or bacteria (e.g. Haemophilus influenzae, Streptococcus pneumoniae and Staphylococcus aureus). Epstein-Barr virus (EBV) is the causative agent in 2% of cases. The beta-haemolytic Streptococcus group A subtype (that may also cause scarlet fever) used to be notorious for causing complications but this is less common nowadays.
A distinction between the viral and bacterial causes of tonsillitis cannot reliably be made in the office.
Patients with tonsillitis most often present complaining of a sore throat. Other coldlike symptoms are often present. In addition, the tonsils are swollen and red and there is exudate present. Lymph nodes in the neck region may be swollen and painful. Patients’ temperatures can be (sub)febrile. Tonsillitis is a ‘clinical’ diagnosis and additional diagnostic tests are not necessary. It may occur in isolation or it may overlap with pharyngitis. Sometimes, the two conditions are referred to as ‘pharyngotonsillitis’. The clinical picture of the Epstein-Barr virus infection is called ‘infectious mononucleosis’ and includes fever, pharyngitis (or pharyngotonsillitis) and lymphadenopathy.
Tonsillitis in most cases tends to last between seven and ten days, regardless of the pathogen. Treatment is focused on symptom relief with analgesics. Dutch GPs will apply ‘watchful waiting’, which is possible in the context of easily accessible and continuous GP care for everyone in the Netherlands, allowing patients to come back if symptoms persist or worsen. The Dutch College of General Practitioners advises against antibiotics, unless the patient is seriously ill or has an increased risk of complications. In these cases, small-spectrum antibiotics are advised.
Complications may occur when the inflammation expands to the tissue between the tonsil and pharyngeal muscle. This is called a peritonsillar cellulitis (also named peritonsillitis) or a peritonsillar abscess (when pus is present). It is difficult to differentiate between these diagnoses and if suspected, the patient should be referred to the otorhinolaryngologist, especially when the patient is very ill, immunocompromised, or has difficulty swallowing or opening the mouth. If this is not the case, the GP should prescribe a broad-spectrum antibiotic and frequently check on the patient. In the very rare case of an (imminent) upper airway obstruction, an emergency referral is needed.
In young children, ‘cervical lymphadenitis’ is a rare complication of tonsillitis in which the lymph nodes themselves get infected, usually with a Staphylococcus or Streptococcus bacteria. Broad spectrum antibiotics or referral are indicated in this case.
Acute tonsillitis, including peritonsillar abscess, is coded ‘R76’ in ICPC-2. The symptom diagnosis ‘throat symptom / complaint’ (R21) is coded as such when the criteria of tonsillitis are not met (e.g. no abnormalities observed in the mouth region). A symptom diagnosis is more likely recorded in telephone or email consultations.
Upper respiratory tract infections (R74) may show overlap with tonsillitis and will be recorded if the clinical picture fits best to that diagnosis. If, along with a (mild) upper respiratory infection, an evident tonsillitis is present and requires intervention, GPs will probably identify tonsillitis as the primary diagnosis and classify it as such (R76). An isolated pharyngitis (without affected tonsils) is classified as ‘R74’.
In addition, proven Streptococcus throat infection (e.g. scarlet fever) is coded ‘R72’ and proven infectious mononucleosis (caused by the Epstein-Barr virus) is coded ‘A75’. This means that mild cases of scarlet fever and mononucleosis, in which no further testing is performed, will likely be coded ‘R76’ (when tonsils show signs of inflammation) or ‘R74’ (when symptoms mimic a common cold or pharyngitis). Finally, an acute (cervical) lymphadenitis is coded ‘B70’.
The overall incidence of tonsillitis is 8.1 per 1000 patient years. Incidence of tonsillitis differs between age and sex groups. It occurs frequently under the age of 45 and is much less common in older age groups. Incidence is generally higher among females (9.6 per 1000 patient years, compared to 6.6 among men), with the highest incidence in females in the age group 15-24 years. Among boys and men, the incidence of tonsillitis is highest in the youngest age group (0-4 years), at 19.8 per 1000 patient years. Link/Figure 1
The prevalence of tonsillitis is 8.3 per 1000 patient years, meaning that among 1000 patients in a year, eight seek help from their GP for tonsillitis. The prevalence shows similar fluctuations among different age and sex groups as the incidence. Link/Figure 2
The similar incidence and prevalence rates reflect that tonsillitis is an episodic (acute) disorder.
The rolling three year averages graph shows a smoothened trend curve with an obvious decrease in the incidence and prevalence of tonsillitis in 2020, which was an effect of the COVID-19 pandemic.
The symptom diagnosis throat pain (R21) has an incidence of 13.3 per 1000 patient years. Link/Figure 3
Infectious mononucleosis (A75) has a low (0.7 per 1000 patient years) overall incidence, occurring mainly in the age group 15-24 years (2.6 per 1000 patient years for those aged 15-24 and is 3.8 among girls / women and 1.4 among boys / men). Link/Figure 4 A Streptococcus throat infection (R72) has become an uncommon diagnosis (with an incidence of 0.4 per 1000 patient years). Link/Figure 5
Acute lymphadenitis (B70) also has a low incidence rate (0.5 per 1000 patient years). Link/Figure 6
The most common initial reason for encounter (RFE) for tonsillitis is throat symptom / complaint (R21), in 53% of all new episodes. This Figure 5 Figure 6 Table 7 Tonsillitis (R76) 80 is followed by fever (A03), in 15%, and tonsillitis (R76) itself, in 10%, meaning that patients already believe the diagnosis is tonsillitis when the consultation starts. Link/Table 7
Fever (A03) is the most common RFE among children aged 0-4 with tonsillitis. Link/Table 8
In 10% of episodes of tonsillitis (including peritonsillar abscess), a referral to the otorhinolaryngologist and, in rare cases, the paediatrician, occurs. Link/Table 9
In 61% of episodes, medication is prescribed. Link/Table 10 This concerns (small spectrum) beta-lactam sensitive penicillin (J01CE, e.g. pheneticillin), in 32%, (broad spectrum) penicillin combinations (J01CR, e.g. amoxicillin with beta-lactamase inhibitor), in 10%, and macrolides (J01FA, e.g. azithromycin, rythromycin), in 8% of episodes. Link/Table 11 Other prescribed drugs include NSAIDs (M01A, in 10% of episodes) or occasionally other analgesics. Link/Table 12 The percentage of prescriptions is higher among older patients with tonsillitis (81% in patients aged 45 and older). Link/Table 13 Percentages of referrals and antibiotic prescriptions may seem relatively high. Probably, this reflects GPs’ classification habits, making ‘tonsillitis’ (R76) the most likely diagnostic label when a specific intervention is warranted for tonsillitis, but at the same time the patient has symptoms that could fit a diagnostic label of an ‘upper respiratory airway infection’ (R74).
Over the years, the percentage of annual prescriptions of antibiotics for tonsillitis has gradually decreased. Comparing the calendar years 2014-2015 (Link/Table 14) to 2016-2021 (Link/Table 15), it becomes clear that the prescribing of penicillin as a group (i.e. choosing four rather than five digits in the ATC classification, which classifies broad and small spectrum penicillin in one group) decreases from 46% (2014-2015) to 43% (2016-2021). Macrolide prescriptions also fell from 13%, in 2014-2015, to 7%, in 2016-2021. This decline in antibiotic prescription may be the result of the adjusted guideline for acute throat symptoms as published by the Dutch College of General Practitioners in 2015, advising restraint in prescribing antibiotics, which may have led to a gradual shift in GPs’ prescribing behaviour. On the website, it is possible to modify variables, such as age group, sex, calendar period or, for prescriptions, the level of detail of medication classes, according to the ATC level, as required.
Dutch guideline: https://richtlijnen.nhg.org/standaarden/acute-keelpijn#volledige-tekst (2015)
