Methodology
The relationship between the haemoglobin concentration and the haematocrit in Plasmodium falciparum malaria
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* Corresponding author: Nicholas J White nickw@tropmedres.ac
1 Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand
2 Menzies School of Health Research and Royal Darwin Hospital, Darwin, NT, Australia
3 Shoklo Malaria Research Unit, Mae Sot, Thailand
4 University of Cape Town, South Africa
5 Choray Hospital, Ho Chi Minh City, Vietnam
6 Institute of Tropical Medicine, Antwerp, Belgium
7 Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK
8 Division of Infectious Diseases, Tropical Medicine & AIDS, Academic Medical Center, Amsterdam, The Netherlands
9 University of California, San Francisco, CA, USA
10 Institut de Recherche en Sciences de la Sante, Burkino Faso
11 Uganda Malaria Surveillance Programme, Uganda
12 Epicentre, France
13 National University of Laos, Laos
14 Wellcome Trust- Mahosot Hospital- Oxford University Tropical Medicine Research Collaboration, Laos
15 WHO TDR, Geneva, Switzerland
16 Centro Internatcional de Entrenamiento e Investigaciones Medicas, Colombia
17 London School of Hygiene & Tropical Medicine, London, UK
18 Médecins sans Frontières, The Netherlands
Malaria Journal 2008, 7:149 doi:10.1186/1475-2875-7-149
Published: 2 August 2008Abstract
Background
Malaria is a very important cause of anaemia in tropical countries. Anaemia is assessed either by measurement of the haematocrit or the haemoglobin concentration. For comparisons across studies, it is often necessary to derive one measure from the other.
Methods
Data on patients with slide-confirmed uncomplicated falciparum malaria were pooled from 85 antimalarial drug trials conducted in 25 different countries, to assess the haemoglobin/haematocrit relationship at different time points in malaria. Using a linear random effects model, a conversion equation for haematocrit was derived based on 3,254 measurements from various time points (ranging from day 0 to day 63) from 1,810 patients with simultaneous measurements of both parameters. Haemoglobin was also estimated from haematocrit with the commonly used threefold conversion.
Results
A good fit was obtained using Haematocrit = 5.62 + 2.60 * Haemoglobin. On average, haematocrit/3 levels were slightly higher than haemoglobin measurements with a mean difference (± SD) of -0.69 (± 1.3) for children under the age of 5 (n = 1,440 measurements from 449 patients).
Conclusion
Based on this large data set, an accurate and robust conversion factor both in acute malaria and in convalescence was obtained. The commonly used threefold conversion is also valid.