Spectrophotometry assays to determine G6PD activity from Trinity Biotech and Pointe Scientific G6PD show good correlation

Objectives: Spectrophotometry kits from Pointe Scientific (PS; USA) were compared to kits from Trinity Biotech (Trinity; Ireland) in 50 venous blood samples from purposively selected individuals in Bangladesh. Repeatability and inter-assay variability were assessed by Students t-test, Bland-Altman plot and Pearson correlation coefficient (r). The median glucose-6-phosphate dehydrogenase (G6PD) activity of all G6PD normal participants was calculated per assay and defined as 100% activity. Performance was calculated considering 30% and 70% cut off activities and Trinity as reference.

Results: The intra-assay correlation of Trinity (r = 0.9841, p < 0.001) and PS (r = 0.9833, p < 0.001) did not differ significantly (p = 0.904). Both assays were closely correlated (r = 0.9799, p < 0.001), with a mean difference of 0.1 U/gHb (95% limit of agreement: - 1.32 to 1.57). At 30% cut off PS had a sensitivity of 100% (95% confidence interval (95 CI) 59.0-100.0) and specificity of 100% (95% CI 91.8 to 100.0), at 70% cut-off of 100% (95% CI 79.4-100.0) and 97.1% (95% CI 84.7-99.9) respectively. The G6PD assay from PS is a reliable alternative to the assay from Trinity.