Validity of impedance-based equations for the prediction of total body water as measured by deuterium dilution in African women.
BACKGROUND
Little information is available on the validity of simple and indirect body-composition methods in non-Western populations. Equations for predicting body composition are population-specific, and body composition differs between blacks and whites.


OBJECTIVE
We tested the hypothesis that the validity of equations for predicting total body water (TBW) from bioelectrical impedance analysis measurements is likely to depend on the racial background of the group from which the equations were derived.


METHODS
The hypothesis was tested by comparing, in 36 African women, TBW values measured by deuterium dilution with those predicted by 23 equations developed in white, African American, or African subjects. These cross-validations in our African sample were also compared, whenever possible, with results from other studies in black subjects.


RESULTS
Errors in predicting TBW showed acceptable values (1.3-1.9 kg) in all cases, whereas a large range of bias (0.2-6.1 kg) was observed independently of the ethnic origin of the sample from which the equations were derived. Three equations (2 from whites and 1 from blacks) showed nonsignificant bias and could be used in Africans. In all other cases, we observed either an overestimation or underestimation of TBW with variable bias values, regardless of racial background, yielding no clear trend for validity as a function of ethnic origin.


CONCLUSIONS
The findings of this cross-validation study emphasize the need for further fundamental research to explore the causes of the poor validity of TBW prediction equations across populations rather than the need to develop new prediction equations for use in Africa.
Dioum
Aïssatou
A
Equipe de Nutrition, Laboratoire de Physiologie, Département de Biologie Animale, Faculté des Sciences et Techniques, Université Cheikh Anta Diop de Dakar, Sénégal, West Africa.
Gartner
Agnès
A
Cissé
Aïta S
AS
Delpeuch
Francis
F
Maire
Bernard
B
Wade
Salimata
S
Schutz
Yves
Y
D000293:Adolescent; D000328:Adult; D015982:Bias; D044383:Black People / Q000208:ethnology; D001823:Body Composition / Q000502:physiology*; D001834:Body Water / Q000378:metabolism* / Q000502:physiology; D003903:Deuterium; D017097:Electric Impedance; D005006:Ethnicity; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D044465:White People / Q000208:ethnology; D001741:Black or African American
D003903:Deuterium