Point-of-care CRP testing in the diagnosis of pneumonia in adults

Abstract

Respiratory tract infections (RTI) are among the most common acute conditions leading to GP consultations and to antibiotic prescribing in primary care, even though 70% are viral, and many others are minor self-limiting bacterial infections.^1-4 Between 0.5% and 1.1% of adults have community-acquired pneumonia every year in the UK, most of whom are managed in primary care.^4,5 The decision to prescribe antibiotics for an acute RTI in primary care is often based on clinical symptoms, which have low sensitivity and specificity, and high inter-observer variability.^2,4 In primary care, it is very difficult to differentiate between diagnoses without additional tests.⁶ Unnecessary antibiotic prescribing may not aid recovery, exposes patients to potential adverse effects, may encourage repeat attendance and contributes to antibiotic resistance.^2,7 One strategy aiming to reduce antibiotic prescribing in primary care is the use of biomarkers (e.g. C-reactive protein [CRP]).² In the correct clinical context (e.g. in previously healthy people, not those with chronic lung disease) and as an adjunct to clinical assessment, a biomarker may help in the management of an RTI.² In order to be used during the consultation, the results of a biomarker test must be rapidly available (e.g. 'point-of-care' [POC] testing).⁴ POC testing for CRP has recently been recommended as part of a national clinical guideline on the diagnosis and management of pneumonia.⁴ Here, we review the rationale for POC CRP testing and its advantages and disadvantages.