Cohen J H, Haas J D
Program in International Nutrition, Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Int J Epidemiol. 1999 Feb;28(1):82-9. doi: 10.1093/ije/28.1.82.
A maximum likelihood method of mixed distribution analysis (MDA) is presented as a method to estimate the prevalence of iron deficiency anaemia (IDA) in Costa Rican infants 12-23 months old. MDA characterizes the parameters of the admixed distributions of iron deficient anaemics and non-iron-deficient-anaemics (NA) from the frequency distribution of haemoglobin concentration of the total sample population.
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 haemoglobin distributions determined by MDA and the widely used three-criteria model of iron deficiency. The estimates of the prevalence of IDA by each of the methods were compared. The sensitivity and specificity of MDA compared to diagnosis by the three-criteria method were assessed. Simulations were carried out to assess the comparability of MDA and the three-criteria method in low and high prevalence scenarios.
The mean and standard deviation (SD) of the NA haemoglobin distribution 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-criteria method were 24% and 29%, respectively. The sensitivity and specificity of MDA were 95% and 97%, respectively. The performance of MDA was similar to the three-criteria method at a simulated high prevalence of IDA and less similar at a low prevalence of IDA.
Compared to the reference three-criteria method MDA provides a more accurate estimate of the true prevalence of IDA than the haemoglobin cutoff 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 severity of IDA in populations with moderate to high prevalences of IDA, and for assisting in the design, monitoring and evaluation of iron intervention programmes.
提出了一种混合分布分析的最大似然法（MDA），作为估计哥斯达黎加12至23个月大婴儿缺铁性贫血（IDA）患病率的方法。MDA从总样本人群血红蛋白浓度的频率分布中，表征缺铁性贫血患者和非缺铁性贫血患者（NA）混合分布的参数。
使用Lozoff等人（1986年）收集的345名12至23个月大的哥斯达黎加婴儿的数据，来估计由MDA确定以及广泛使用的缺铁三项标准模型确定的IDA和NA血红蛋白分布的参数。比较了每种方法对IDA患病率的估计值。评估了MDA与三项标准法诊断相比时的敏感性和特异性。进行模拟以评估MDA和三项标准法在低患病率和高患病率情况下的可比性。
两种方法确定的NA血红蛋白分布的均值和标准差（SD）为12.1±1.0g/dL。MDA确定的IDA血红蛋白分布的均值和SD为10.2±1.3g/dL，而三项标准法确定的IDA分布的均值和SD为10.4±1.3g/dL。MDA和三项标准法估计的IDA患病率分别为24%和29%。MDA的敏感性和特异性分别为95%和97%。在模拟的IDA高患病率时，MDA与三项标准法表现相似，而在IDA低患病率时相似性较低。
与参考三项标准法相比对于12至23个月大、IDA患病率为中度至高患病率的儿童群体，MDA比血红蛋白临界值法能更准确地估计IDA的真实患病率。对于IDA患病率为中度至高患病率的人群，MDA是一种成本较低的方法，可用于估计IDA的严重程度，并协助设计、监测和评估铁干预项目。
