The relationship between the haemoglobin concentration and the haematocrit in Plasmodium falciparum malaria.
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).


CONCLUSIONS
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.
Lee
Sue J
SJ
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. sue@tropmedres.ac
Stepniewska
Kasia
K
Anstey
Nicholas
N
Ashley
Elizabeth
E
Barnes
Karen
K
Binh
Tran Quang
TQ
D'Alessandro
Umberto
U
Day
Nicholas P J
NP
de Vries
Peter J
PJ
Dorsey
Grant
G
Guthmann
Jean-Paul
JP
Mayxay
Mayfong
M
Newton
Paul
P
Nosten
Francois
F
Olliaro
Piero
P
Osario
Lyda
L
Pinoges
Loretxu
L
Price
Ric
R
Rowland
Mark
M
Smithuis
Frank
F
Taylor
Robert
R
White
Nicholas J
NJ
D000465:Algorithms; D002675:Child, Preschool; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood* / Q000175:diagnosis; D011237:Predictive Value of Tests
D006454:Hemoglobins