Sensitivity and specificity of mean corpuscular volume testing for screening for alpha-thalassemia-1 and beta-thalassemia traits.
OBJECTIVE
To evaluate the sensitivity, specificity, positive predictive value and negative predictive value of mean corpuscular volume (MCV) testing for screening for both alpha-thalassemia-1 and beta-thalassemia traits.


METHODS
A diagnostic test was conducted on 439 pregnant women attending the antenatal care (ANC) clinic at Maharaj Nakorn Chiang Mai Hospital between April 2002 and July 2002. Blood samples were collected from the pregnant women after they were counseled and gave informed consent. The MCV was measured in all samples using an automated hematology analyzer. The hemoglobin (HbA2) level and polymerase chain reaction (PCR) were measured in all cases to test for the beta-thalassemia trait and the alpha-thalassemia-1 gene (South-East Asian [SEA] type), respectively. The data were collected and analyzed for sensitivity, specificity, positive predictive value and negative predictive value for evaluating the efficacy of MCV testing for screening for both alpha-thalassemia-1 and beta-thalassemia traits.


RESULTS
Positive MCV tests (</=80 fl) showed a sensitivity of 92.9% and specificity of 83.9% in screening for alpha-thalassemia-1 and beta-thalassemia traits, respectively. The positive predictive value and negative predictive value were 37.9% and 99.1%, respectively.


CONCLUSIONS
MCV evaluation is a useful tool for screening for alpha-thalassemia-1 and beta-thalassemia traits during pregnancy because of its simplicity, low cost and high sensitivity.
Sirichotiyakul
Supatra
S
Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand. ssiricho@mail.med.cmu.ac.th
Maneerat
Jatuchai
J
Sa-nguansermsri
Torpong
T
Dhananjayanonda
Pisawat
P
Tongsong
Theera
T
D000328:Adult; D004909:Erythrocyte Indices; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000097:blood / Q000175:diagnosis*; D011296:Prenatal Diagnosis; D012680:Sensitivity and Specificity; D017085:alpha-Thalassemia / Q000097:blood / Q000175:diagnosis*; D017086:beta-Thalassemia / Q000097:blood / Q000175:diagnosis*