Oral Presentation First Malaria World Congress 2018

Field evaluation of point of care assays for quantifying Glucose-6-Phosphate Dehydrogenase activity (#208)

Mohammad Shafiul Alam 1 , Mohammad Golam Kibria 1 , Nusrat Jahan 1 , Kamala Ley-Thriemer 2 , Mohammad Sharif Hossain 1 , Ching Swe Phru 1 , Wasif A. Khan 1 , Ric N. Price 2 3 , Benedikt Ley 2
  1. icddr,b, Dhaka, DHAKA, Bangladesh
  2. Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Casuarina , NT, Australia
  3. Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom

Introduction: Individuals with G6PD deficiency (G6PDd) are at risk of drug induced haemolysis following primaquine and tafenoquine. The WHO recommends G6PD testing whenever possible prior to prescribing radical cure. Current point of care (PoC) G6PDd diagnostics are qualitative and detect enzyme deficiency below 30%. Tafenoquine will soon be introduced to the market and offer single dose radical cure, but will only be recommended in patients with ≥80% activity. This study evaluated the performance of two novel quantitative PoCs with operational characteristics suitable to guide Tafenoquine treatment.

Methods: Participants with known G6PD activity were selected purposively and enrolled in the Chittagong Hill Tracts, Bangladesh. 5ml venous blood were collected for immediate testing with the Biosensor® (Carestart, USA) and the G6PD STANDARD (SDBiosensor, South Korea). Samples were then stored in EDTA at 4°C, sent to a reference laboratory within 24 hours and retested with either device and by spectrophotometry.

Results: The Biosensor was assessed on 158 samples, the G6PD STANDARD on 108 samples. The Biosensor® was highly correlated with spectrophotometry (rs=0.7729; p<0.001, n=152), with a mean difference of -0.7 U/gHb (95% limit of agreement (LoA): -4.82 to 3.38), correlation was even higher for the G6PD STANDARD (rs=0.9145, p<0.001, n=108) with a mean difference of -0.8 U/gHb and 95%LoA of -3.10 to 1.44. The sensitivity and specificity of the Biosensor at 80% cut off activity (as defined by spectrophotometry) were 66.3% (95% Confidence Interval (CI): 55.3-76.1) and 97.0% (95%CI: 89.5-99.6) and 86.6% (95%CI: 76.0-93.7) and 92.7% (95%CI: 80.1-98.5) for the G6PD STANDARD. When applying optimal cut offs, sensitivity and specificity of the Biosensor increased to 86.4% and 77.9% and for the G6PD STANDARD to 95.1% and 86.6%.

Conclusion: The PoC quantitative assays performed well in the laboratory and may provide reliable sensitivity at detecting heterozygous females at risk of drug induced haemolysis.