Direct-to-consumer point-of-care in vitro diagnostic devices for group A streptococcal infections

A pragmatic approach to interpretation for healthcare professionals involved in the investigation and management of patients with acute pharyngitis.

1. Summary

This document provides consensus best practice principles to support clinician-led decision making when assessing patients with sore throat who present with a direct-to-consumer point-of-care in vitro diagnostic device (POC-IVDD) result for group A streptococcus (GAS). It will also aid subsequent management conversations with the patient or their caregiver. 

These principles were developed by the NHS England Diagnostics Board and the UK Health Security Agency (UKHSA) and include representation from academic and frontline clinicians across primary and secondary care settings. These principles are endorsed by the British Infection Association and the Royal College of General Practitioners. The National Institute for Health and Care Excellence (NICE) is aware of the development of these principles.

2. Target audience

Healthcare professionals working in healthcare settings in England who see patients presenting with sore throat, acute respiratory infections, or influenza-like illness. This includes primary care, urgent care centres, and emergency departments.

3. Background

GAS is a bacterium that can colonise the throat, skin and anogenital tract. It can also cause a diverse range of clinical presentations such as skin, soft tissue, and respiratory tract infections, including tonsillitis, pharyngitis and scarlet fever. On rare occasions, GAS can cause severe and invasive infections including pneumonia and septicaemia, and may cause post-viral respiratory tract secondary infections.

Sore throat (pharyngitis) is a common and usually self-limiting condition. Most sore throats are caused by viruses, and the risk of progression to serious disease is low. NICE guidance on sore throat management (NICE NG84) currently recommends 2 clinical prediction scoring systems – FeverPAIN and Centor – which aim to identify people who may be more likely to benefit from an antibiotic. According to the cumulative clinical score, NICE recommends either no, delayed, or immediate antibiotic prescriptions.

NICE does not currently recommend routine use of POC-IVDDs for the diagnosis of GAS infections in people with a sore throat in England, as they are unlikely to be a cost-effective use of NHS resources (NICE DG38). However, POC-IVDDs are increasingly available direct to the consumer through a variety of online and in-person merchants, and healthcare professionals may be presented with a test result in the context of a clinical consultation.

There are a range of POC-IVDDs for GAS currently available on the market, and historical performance of POC-IVDDs in several settings and for a variety of pathogens suggest the validity of the result cannot always be assured.

4. Best practice principles

It is recommended that clinicians adopt a patient-centric approach when interpreting results of a self-administered POC-IVDD designed to detect GAS.

The following best practice principles should be considered:

  • Healthcare professionals are advised to take account of the clinical presentation of the patient and clinical scoring systems, such as FeverPAIN and Centor, alongside the test result to agree a pragmatic and holistic management plan with the patient and/or caregiver. This is especially important when there may be discordance between the test and clinical scoring systems/guidance.
  • In situations of continued uncertainty, healthcare professionals may wish to consider sending a throat swab for culture if it would impact clinical management.
  • The significance of GAS when detected in the pharynx can be difficult to determine; this can range from it being an infecting pathogen, or co-pathogen (for example, exacerbating a viral aetiology), to throat carriage. Tests should not be performed in asymptomatic individuals as the clinical significance of results cannot be determined.
  • Patients must receive clear safety netting information (see sore throat or tonsillitis on the website) regardless of whether antibiotics are prescribed or not. Use of the appropriate TARGET leaflet should be considered.
  • Scarlet fever remains principally a clinical diagnosis, and a POC-IVDD result should not replace the need for antibiotic treatment and notification to local health protection teams.