Economic considerations support C-reactive protein testing alongside malaria rapid diagnostic tests to guide antimicrobial therapy for patients with febrile illness in settings with low malaria endemicity.

Malaria is no longer a common cause of febrile illness in many regions of the tropics. In part, this success is a result of improved access to accurate diagnosis and effective anti-malarial treatment, including in many hard-to-reach rural areas. However, in these settings, management of other causes of febrile illness remains challenging. Health systems are often weak and other than malaria rapid tests no other diagnostics are available. With millions of deaths occurring annually due to treatable bacterial infections and the ever increasing spread of antimicrobial resistance, improvement in the management of febrile illness is a global public health priority. Whilst numerous promising point-of-care diagnostics are in the pipeline, substantial progress can be made in the interim with existing tools: C-reactive protein (CRP) is a highly sensitive and moderately specific biomarker of bacterial infection and has been in clinical use for these purposes for decades, with dozens of low-cost devices commercially available. This paper takes a health-economics approach to consider the possible advantages of CRP point-of-care tests alongside rapid diagnostic tests for malaria, potentially in a single multiplex device, to guide antimicrobial therapy for patients with febrile illness. Three rudimentary assessments of the costs and benefits of this approach all indicate that this is likely to be cost-effective when considering the incremental costs of the CRP tests as compared with either (i) the improved health outcomes for patients with bacterial illnesses; (ii) the costs of antimicrobial resistance averted; or (iii) the economic benefits of better management of remaining malaria cases and shorter malaria elimination campaigns in areas of low transmission. While CRP-guided antibiotic therapy alone cannot resolve all challenges associated with management of febrile illness in remote tropical settings, in the short-term a multiplexed CRP and malaria RDT could be highly cost-effective and utilize the well-established funding and distribution systems already in place for malaria RDTs. These findings should spark further interest amongst industry, academics and policy-makers in the development and deployment of such diagnostics, and discussion on their geographically appropriate use.