ABSTRACT
To improve the efficiency of thalassemia screening, problems related to the screening procedures had been assessed in 3 community hospitals i.e. Thatako Hospital; Nakornsawan province, Lansaka Hospital; Nakhon Si thammarat province, and Borabue Hospital; Mahasarakham province. The investigation was done in 3 phases. Phase I aimed to identify the problems of routine thalassemia screening. From each hospital, blood samples screened for routine services were collected and sent to the Thalassemia Research Project, the Center for Research and Development in Medical Diagnostic Laboratory (CMDL) at the Khon Kaen University for confirmation. False positive and false negative rates were determined to assess the accuracy of the results. It was found that the range of false positive and false negative rates of the osmotic fragility test (OF test) for screening of α-thalassemia 1 and β-thalassemia was 7.9-29.6% and 0-100%, respectively. The DCIP precipitation test (DCIP-test) used for Hb E screening resulted in a range for false positive results of 1.4-4.0% and for false negative results of 3.6-50%. A combination of the OF/DCIP test revealed 10.5 to 29.6% false positive- and 3.5 to 42.9%, false negative results. In phase II the causes for the measuring errors were identified. These varied from hospital to hospital. Most of the causes were related to mistakes made by the laboratory personnels. A workshop on thalassemia screening was convened to improve the skills of the laboratory staff to perform screening tests correctly. Modified laboratory procedures were implemented in each hospital. Reassessment of the efficiency of thalassemia screening was conducted again by collecting blood samples screened for thalassemia from each hospital and sent to the CMDL for confirmation. The sensitivity and specificity of the combined tests increased considerably from 57.1-96.6% to 97.1-100% and 70.4-88.9% to 81.5-89.9% indicating that the efficiency of thalassemia screening had been improved. The results indicated that the proficiency testing system should be implemented at community hospitals to standardize and improve the quality of thalassemia and hemoglobinopathies screening within Thailand.