Clinical relevance of different biomarkers in imported plasmodium falciparum malaria in adults: a case control study

BACKGROUND: For rapid initiation of anti-malarial treatment and prevention of complications, early diagnosis and risk stratification is important in patients with Plasmodium falciparum malaria. Routine laboratory values do not correlate well with disease severity. The aim of this study was to determine the diagnostic and prognostic value of several biomarkers related to inflammation; endothelial and cardiac dysfunction; coagulation, and haemolysis in imported P. falciparum malaria.

METHODS: In a prospective case-control study, 79 adult travellers with both uncomplicated and complicated P. falciparum malaria were included between 2007 and 2011. Forty-one healthy subjects were included as controls. Blood samples were obtained within 24 hours after first consultation to assess routine laboratory values as well as markers related to inflammation (PAPP-A, copeptin, CRP), endothelial activation (MPO, elastase-2, endothelin-1, sICAM-1, sVCAM-1), cardiac function (NT-proBNP, MR-proANP), coagulation (fibrinogen, D-dimers, platelet count), and haemolysis (LDH). Prognostic performance was assessed using the receiver operating characteristic curve (area under the curve = AUROC).

RESULTS: Twelve (15.2%) patients had severe P. falciparum malaria. In the patient group, significant thrombocytopaenia was found, all other markers but PAPP-A were significantly elevated. Diagnostic performance was best for CRP with an AUROC of 1.00, followed by MPO (0.99), D-dimers (0.98), elastase-2 (0.98), and sICAM-1 (0.98). Biomarker levels did not correlate well with disease severity.

CONCLUSION: The combination of travel history, fever prior to blood sampling, and CRP serum levels above or below 10.8 mg/l upon hospital admission, best discriminated between malaria patients and control persons. None of the biomarkers studied predicted the presence or the development of malaria complications, neither at the time of admission, nor during hospitalization.