The comparison of mixed distribution analysis with a three-criteria model as a method for estimating the prevalence of iron deficiency anaemia in Costa Rican children aged 12-23 months
Jh. Cohen et Jd. Haas, The comparison of mixed distribution analysis with a three-criteria model as a method for estimating the prevalence of iron deficiency anaemia in Costa Rican children aged 12-23 months, INT J EPID, 28(1), 1999, pp. 82-89
Citations number
30
Categorie Soggetti
Envirnomentale Medicine & Public Health","Medical Research General Topics
Background A maximum likelihood method of mixed distribution analysis (MDA)
is presented as a method to estimate the prevalence of iron deficiency ana
emia (IDA) in Costa Rican infants 12-23 months old. MDA characterizes the p
arameters of the admixed distributions of iron deficient anaemics and non-i
ron-deficient-anaemics (NA) from the frequency distribution of haemoglobin
concentration of the total sample population.
Methods Data collected by Lozoff et al. (1986) from 345 Costa Rican infants
12-23 months old were used to estimate the parameters of the IDA and NA ha
emoglobin distributions determined by MDA and the widely used three-criteri
a model of iron deficiency. The estimates of the prevalence of IDA by each
of the methods were compared. The sensitivity and specificity of MDA compar
ed to diagnosis by the three-criteria method were assessed. Simulations wer
e carried out to assess the comparability of MDA and the three-criteria met
hod in low and high prevalence scenarios.
Results The mean and standard deviation (SD) of the NA haemoglobin distribu
tion determined by both methods was 12.1 +/- 1.0 g/dL. The IDA haemoglobin
distribution determined by MDA had a mean and SD of 10.2 +/- 1.3 g/dL while
the IDA distribution by the three-criteria method had a mean and SD of 10.
4 +/- 1.3 g/dL. The prevalences of IDA as estimated by MDA and the three-cr
iteria method were 24% and 29%, respectively. The sensitivity and specifici
ty of MDA were 95% and 97%, respectively. The performance of MDA was simila
r to the three-criteria method at a simulated high prevalence of IDA and le
ss similar at a low prevalence of IDA.
Conclusions Compared to the reference three-criteria method MDA provides a
more accurate estimate of the true prevalence of IDA than the haemoglobin c
utoff method in a population of children aged 12-23 months with a moderate
to high prevalence of IDA. MDA is a less costly method for estimating the s
everity of IDA in populations with moderate to high prevalences of IDA, and
for assisting in the design, monitoring and evaluation of iron interventio
n programmes.