title: The clinical implications of thrombocytopenia in adults with severe falciparum malaria: a retrospective analysis.
abstract: BACKGROUND
  Thrombocytopenia is a common finding in adults with severe falciparum malaria, but its clinical and prognostic utility is incompletely defined.
  
  
  METHODS
  Clinical and laboratory data from 647 adults with severe falciparum malaria were analysed retrospectively to determine the relationship between a patient's platelet count on admission to hospital and their subsequent clinical course.
  
  
  RESULTS
  On admission, 614 patients (94.9%) were thrombocytopenic (platelet count <150 × 10(9)/L) and 328 (50.7%) had a platelet count <50 × 10(9)/L. The admission platelet count was inversely correlated with parasite biomass (estimated from plasma PfHRP2 concentrations, rs = -0.28, P = 0.003), the degree of microvascular sequestration (measured with orthogonal polarizing spectral imaging, rs = -0.31, P = 0.001) and disease severity (the number of World Health Organization severity criteria satisfied by the patient, rs = -0.21, P <0.001). Platelet counts were lower on admission in the patients who died (median: 30 (interquartile range 22 to 52) × 10(9)/L versus 50 (34 to 78) × 10(9)/L in survivors; P <0.001), but did not predict outcome independently from other established laboratory and clinical prognostic indices. The 39 patients (6%) with profound thrombocytopenia (platelet count <20 × 10(9)/L) were more likely to die (odds ratio: 5.00, 95% confidence interval: 2.56 to 9.75) than patients with higher platelet counts, but these high-risk patients could be identified more rapidly with simple bedside clinical assessment. The admission platelet count did not reliably identify the 50 patients (7.7%) with major bleeding during the study.
  
  
  CONCLUSIONS
  Thrombocytopenia is a marker of disease severity in adults with falciparum malaria, but has limited utility in prognostication, triage and management.
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. drjoshhanson@gmail.com.|Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, NT, Australia. drjoshhanson@gmail.com.
authors.forename: Josh
authors.initials: J
authors.lastname: Hanson
authors.affiliation: Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam. phunh@oucru.org.
authors.forename: Nguyen Hoan
authors.initials: NH
authors.lastname: Phu
authors.affiliation: Chittagong Medical College, Chittagong, Bangladesh. mahtabnipu@yahoo.com.
authors.forename: Mahtab Uddin
authors.initials: MU
authors.lastname: Hasan
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. jib@tropmedres.ac.
authors.forename: Prakaykaew
authors.initials: P
authors.lastname: Charunwatthana
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. kaplewes@gmail.com.
authors.forename: Katherine
authors.initials: K
authors.lastname: Plewes
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. Richard@tropmedres.ac.|Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK. Richard@tropmedres.ac.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Maude
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. panote.prapansilp@gmail.com.|Department of Laboratory Medicine, Faculty of Medicine, Chulalongkorn University, Chulalongkorn, Thailand. panote.prapansilp@gmail.com.
authors.forename: Panote
authors.initials: P
authors.lastname: Prapansilp
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. hwfkingston@googlemail.com.
authors.forename: Hugh W F
authors.initials: HW
authors.lastname: Kingston
authors.affiliation: Chittagong Medical College, Chittagong, Bangladesh. sarojrkl@gmail.com.
authors.forename: Saroj K
authors.initials: SK
authors.lastname: Mishra
authors.affiliation: Chittagong Medical College, Chittagong, Bangladesh. sanjibmalaria@rediffmail.com.
authors.forename: Sanjib
authors.initials: S
authors.lastname: Mohanty
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, NT, Australia. ricprice99@gmail.com.|Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK. ricprice99@gmail.com.
authors.forename: Ric N
authors.initials: RN
authors.lastname: Price
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. drmafaiz@gmail.com.|Dev Care Foundation, Dhaka, Bangladesh. drmafaiz@gmail.com.
authors.forename: M Abul
authors.initials: MA
authors.lastname: Faiz
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. arjen@tropmedres.ac.|Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK. arjen@tropmedres.ac.
authors.forename: Arjen M
authors.initials: AM
authors.lastname: Dondorp
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. nickwdt@tropmedres.ac.|Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK. nickwdt@tropmedres.ac.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: White
authors.affiliation: Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam. hientt@oucru.org.
authors.forename: Tran Tinh
authors.initials: TT
authors.lastname: Hien
authors.affiliation: Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. nickd@tropmedres.ac.|Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK. nickd@tropmedres.ac.
authors.forename: Nicholas P J
authors.initials: NP
authors.lastname: Day
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000150:complications* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D011379:Prognosis; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000209:etiology* / Q000401:mortality; D055815:Young Adult
chemical_list: D015415:Biomarkers