Evaluating the performance of automated UV enzymatic assay for screening of glucose 6-phosphate dehydrogenase deficiency.

Abstract

A precise and reliable screening assay for glucose 6-phosphate dehydrogenase (G6PD) deficiency would greatly help avoiding unwanted outcomes due to bilirubin neurotoxicity in neonatal jaundice and antimalarial-induced haemolytic anaemia in malaria patients. Currently, available assays are laborious and require sophisticated laboratory expertise. This study aimed to evaluate the performance of a recently introduced automated screening assay for G6PD deficiency by comparing with a routine spectrophotometric assay. An automated UV-based enzymatic (Mindray, PRC) and spectrophotometric assays were performed simultaneously in parallel to determine G6PD activity in 251 blood samples from the subjects. The median G6PD activity value from spectrophotometric assay was significantly lower than that of from the automated assay. The mean difference was -2.0U/g haemoglobin (-7.3 to 3.2; P<0.0001). The mean activity values of both assays were strongly correlated with Pearson's correlation coefficient of r=0.8. Cohen's kappa statistics between assays was 0.77 (0.70-0.83). The sensitivity, specificity, positive and negative predictive values of the automated assay were 85.7%, 99.2%, 85.7%, 99.2%, respectively. The sensitivity and positive predictive values of the automated assay for identifying intermediate G6PD activity levels were 40.0% and 25.0%, respectively. Genotyping was performed to confirm G6PD deficient and intermediate samples. The turnaround time for 40 samples was 60minutes for the automated assay and 300minutes for spectrophotometric assay. The automated assay for the detection of G6PD deficiency is comparable to a routine spectrophotometric assay and help reducing sample handling time. However, the assay shows limitation in identifying individuals with G6PD intermediate.