A comparison of the accuracy of the corpuscular fragility and mean corpuscular volume tests for the alpha-thalassemia 1 and beta-thalassemia traits.
OBJECTIVE
To compare the accuracy of the osmotic fragility test (OFT) and mean corpuscular volume (MCV) calculation when screening for the alpha-thalassemia 1 and/or beta-thalassemia trait.


METHODS
In this cross-sectional study, blood samples from 328 apparently healthy pregnant women were sent on the same day to separate laboratories for the OFT (performed using a glycerol 0.45%, phosphate-buffered, sodium chloride solution) and MCV testing (by means of a standard automated hematology analyzer). A polymerase chain reaction was also performed to positively diagnose alpha-thalassemia 1 carriers, and a quantitative HbA(2) test to positively diagnose beta-thalassemia carriers.


RESULTS
Sensitivity and specificity were 95.0% and 86% for the OFT; and based on the cut-off point of 78.1 fL derived from the ROC curve, they were 93% and 93.4% for MCV calculation. The latter test was found to be slightly more accurate than the OFT in predicting the presence of the alpha-thalassemia 1 and/or beta-thalassemia trait.


CONCLUSIONS
Both tests have high screening sensitivity for the alpha-thalassemia 1 and/or beta-thalassemia traits, and their simplicity and very low cost make them attractive as screening tests for large populations. Since MCV seems to provide fewer false-positive results, it may be the first choice wherever an automated hematology analyzer calculating MCV is available.
Sirichotiyakul
Supatra
S
Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
Wanapirak
Chanane
C
Srisupundit
Kasemsri
K
Luewan
Suchaya
S
Tongsong
Theera
T
D000328:Adult; D003430:Cross-Sectional Studies; D004909:Erythrocyte Indices; D005189:False Positive Reactions; D005260:Female; D006580:Genetic Carrier Screening / Q000379:methods*; D006801:Humans; D008403:Mass Screening / Q000379:methods; D009996:Osmotic Fragility; D016133:Polymerase Chain Reaction / Q000379:methods; D011237:Predictive Value of Tests; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000097:blood / Q000175:diagnosis*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013785:Thailand / Q000453:epidemiology; D055815:Young Adult; D017085:alpha-Thalassemia / Q000097:blood / Q000175:diagnosis*; D017086:beta-Thalassemia / Q000097:blood / Q000175:diagnosis*