Sensitivity and specificity of mean corpuscular volume testing for screening for α‐thalassemia‐1 and β‐thalassemia traits

Aim: To evaluate the sensitivity, specificity, positive predictive value and negative predictive value of mean corpuscular volume (MCV) testing for screening for both α‐thalassemia‐1 and β‐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 β‐thalassemia trait and the α‐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 α‐thalassemia‐1 and β‐thalassemia traits.

Results: Positive MCV tests (≤80 fl) showed a sensitivity of 92.9% and specificity of 83.9% in screening for α‐thalassemia‐1 and β‐thalassemia traits, respectively. The positive predictive value and negative predictive value were 37.9% and 99.1%, respectively.

Conclusion: MCV evaluation is a useful tool for screening for α‐thalassemia‐1 and β‐thalassemia traits during pregnancy because of its simplicity, low cost and high sensitivity.