The dichlorophenol-indophenol (DCIP) test and microcolumn chromatography are simple methods commonly used for screening of Hb E (HBB: c.79G>A) in Thailand. However, there is no proficiency testing (PT) program for these screening tests. Thus, the aim of this study was to evaluate an efficiency of lyophilized hemoglobin (Hb) control materials used in the established PT program for Hb E screening at the Associated Medical Sciences-Clinical Service Center (AMS-CSC), Chiang Mai University, Chiang Mai, Thailand. Three cycles of PT were performed from June 2018 to July 2019. In each cycle, five different types of control materials were provided to the participants. Each participant analyzed the control materials in the same manner as in their routine practices for Hb E screening. The results showed that the number of participants increased from 95 in the first cycle to 126 and 134 in the second and third cycles, respectively. The numbers of participants who used the DCIP screening test and reported the result correctly increased from 79 (85.87%) to 106 (89.08%) and 112 (89.60%), respectively. Whereas those who used the microcolumn chromatography method and reported correct results were decreased from 100.0 to 85.71 and 66.67%, respectively. Thus, lyophilized Hb, control materials can be used effectively for the PT program of Hb E screening test. However, the further improvement, especially in skills of Hb E analysis by microcolumn chromatography, is required for some participating laboratories.
Keywords: Control materials; Hb E (HBB: c.79G>A); dichlorophenol-indophenol; microcolumn chromatography; proficiency testing (PT) program.