Validation of G6PD Point-of-Care Tests among Healthy Volunteers in Yangon, Myanmar

Abstract

Primaquine and other 8-amnoquinoline based anti-malarials can cause haemolysis in subjects with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Correct diagnosis of G6PD status in patients is crucial for safe treatment of both relapsing stages of Plasmodium vivax and transmitting forms of Plasmodium falciparum. Lack of suitable point-of-care tests has hampered a much needed wide use of primaquine for malaria elimination. In this study we have assessed the performances of two qualitative tests, the fluorescent spot test (FST) and the G6PD CareStart test (CST), against the gold standard quantitative spectrophotometric assay in a population of 1000 random adult healthy volunteers living in Yangon, Myanmar. The prevalence of G6PD deficiency in the Bamar, Karen and in the whole sample set was 6.6% (10.1% in males), 9.2% (21.0% in males) and 6.8% (11.1% in males) respectively. The FST and CST showed comparable performances with sensitivity over 95% and specificity over 90%, however for cases with severe G6PD activity the FTS had improved performance. If used with a conservative interpretation of the signal, the CareStart test has the potential to be used in the field and, by allowing a wider use of primaquine, to help malaria elimination.

Fig 1. Distribution of G6PD activity in male and female population.

A: Histograms for ranges of G6PD activity for both males and females based on G6PD activity normalized for hemoglobin concentration. B: Histograms for ranges of G6PD activity for both males and females based on G6PD activity normalized for red blood cell count. The red vertical reference lines are the adjusted population median, the red dashed reference lines are the 30% activity threshold.

Fig 2

Distribution of G6PD activity in women with or without anemia shown as histograms for G6PD activity normalized for (A) hemoglobin concentration and (B) red blood cell count (RBC). Vertical reference line is the population median.

Fig 3. Area under the curve (AUC) vs threshold of G6PD activity (IU/gHb) in the two qualitative tests.

FST results with (a) intermediates combined with deficient test results in red solid lines, (b) intermediates combined with normal test results in red dashed lines. CST results with (a) intermediates combined with deficient test results in blue solid lines, (b) intermediates combined with normal test results in blue dashed lines.

Fig 4. Example of samples from a G6PD deficient male (left, G6PD activity = 1.21 IU/gHb) and G6PD normal male (right, G6PD activity = 7.18 IU/gHb) that were both diagnosed as deficient using the CST test.