Predictive value of cord blood hematological indices and hemoglobin Barts for the detection of heterozygous alpha-thalassemia-2 in an African-Caribbean population.
BACKGROUND
Cord blood hemoglobin Barts (HbBarts) and hemocytometric indices may be used for classification of newborns into those without alpha-thalassemia-2 (alphaalpha/alphaalpha) and with heterozygous alpha-thalassemia-2 (-alpha(3.7)/alphaalpha). We investigated by logistic regression analysis whether the combination of HbBarts and hemocytometric indices improves classification compared with classification based on a single analyte.


METHODS
HbBarts percentages and hemocytometric indices were determined in cord blood of 208 consecutive newborns in Curaçao (Netherlands Antilles). Of these, 157 had alphaalpha/alphaalpha and 51 had -alpha(3.7)/alphaalpha, as established by DNA analysis.


RESULTS
Between-group differences were significant for erythrocytes, mean cell volume, mean cell hemoglobin (MCH), mean cell hemoglobin concentration, platelets, hemoglobin F(0) (HbF(0)), and HbBarts. The Logit equation of the logistic regression model, using MCH (pg) and HbBarts (%), was: 42.7164 + 5.7916(HbBarts) - 1.3110(MCH). A sensitivity of 100% was reached at a Logit value of -3.70. The corresponding specificity was 62.2%, and the predictive value of a positive test (PV+) was 46.3% (95% confidence interval, 37.0-55.7%). The relative information gains were as follows: 88% for the HbBarts-MCH combination, 26% for MCH (not significant), and 0% for HbBarts compared with the 24.6% -alpha(3.7)/alphaalpha prevalence.


CONCLUSIONS
Combined use of cord blood HbBarts and MCH improves classification compared with classification based on single hemocytometric indices.
van der Dijs
F P
FP
Public Health Laboratory, Curaçao, The Netherlands Antilles.
Volmer
M
M
van Gijssel-Wiersma
D G
DG
Smit
J W
JW
van Veen
R
R
Muskiet
F A
FA
D044383:Black People / Q000235:genetics; D001774:Blood Chemical Analysis; D005312:Fetal Blood / Q000737:chemistry*; D005865:Gestational Age; D006455:Hemoglobins, Abnormal / Q000032:analysis*; D006579:Heterozygote; D006801:Humans; D007231:Infant, Newborn; D009427:Netherlands Antilles; D011237:Predictive Value of Tests; D012044:Regression Analysis; D017085:alpha-Thalassemia / Q000097:blood / Q000175:diagnosis* / Q000235:genetics
D006455:Hemoglobins, Abnormal; C030448:hemoglobin Bart's