title: A Comparison of Three Quantitative Methods to Estimate G6PD Activity in the Chittagong Hill Tracts, Bangladesh.
abstract: BACKGROUND
  Glucose-6-phosphate-dehydrogenase-deficiency (G6PDd) is a major risk factor for primaquine-induced haemolysis. There is a need for improved point-of-care and laboratory-based G6PD diagnostics to unsure safe use of primaquine.
  
  
  METHODS
  G6PD activities of participants in a cross-sectional survey in Bangladesh were assessed using two novel quantitative assays, the modified WST-8 test and the CareStart™ G6PD Biosensor (Access Bio), The results were compared with a gold standard UV spectrophotometry assay (Randox). The handheld CareStart™ Hb instrument (Access Bio) is designed to be a companion instrument to the CareStart™ G6PD biosensor, and its performance was compared to the well-validated HemoCue™ method. All quantitative G6PD results were normalized with the HemoCue™ result.
  
  
  RESULTS
  A total of 1002 individuals were enrolled. The adjusted male median (AMM) derived by spectrophotometry was 7.03 U/g Hb (interquartile range (IQR): 5.38-8.69), by WST-8 was 7.03 U/g Hb (IQR: 5.22-8.16) and by Biosensor was 8.61 U/g Hb (IQR: 6.71-10.08). The AMM between spectrophotometry and WST-8 did not differ (p = 1.0) but differed significantly between spectrophotometry and Biosensor (p<0.01). Both, WST-8 and Biosensor were correlated with spectrophotometry (rs = 0.5 and rs = 0.4, both p<0.001). The mean difference in G6PD activity was -0.12 U/g Hb (95% limit of agreement (95% LoA): -5.45 to 5.20) between spectrophotometry and WST-8 and -1.74U/g Hb (95% LoA: -7.63 to 4.23) between spectrophotometry and Biosensor. The WST-8 identified 55.1% (49/89) and the Biosensor 19.1% (17/89) of individuals with G6PD activity <30% by spectrophotometry. Areas under the ROC curve did not differ significantly for the WST-8 and Biosensor irrespective of the cut-off activity applied (all p>0.05). Sensitivity and specificity for detecting G6PD activity <30% was 0.55 (95% confidence interval (95%CI): 0.44-0.66) and 0.98 (95%CI: 0.97-0.99) respectively for the WST-8 and 0.19 (95%CI: 0.12-0.29) and 0.99 (95%CI: 0.98-0.99) respectively for the Biosensor. Hb concentrations measured by HemoCue™ and CareStart™ Hb were strongly correlated (rs = 0.8, p<0.001, mean difference = 0.09 g Hb/dL, 95% LoA: -2.15 to 2.34).
  
  
  CONCLUSIONS
  WST-8 and the CareStart™ G6PD Biosensor represent advances in G6PD diagnostics in resource poor settings, but will require further development before clinical deployment. The CareStart™ Hb instrument produced a precise measure of haemoglobin concentration.
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Ley
authors.affiliation: Infectious Diseases Division, International Centre for Diarrheal Diseases Research, Bangladesh, Mohakhali, Dhaka, Bangladesh.
authors.forename: Mohammad Shafiul
authors.initials: MS
authors.lastname: Alam
authors.affiliation: Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria, Australia.
authors.forename: James J
authors.initials: JJ
authors.lastname: O'Donnell
authors.affiliation: Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria, Australia.
authors.forename: Mohammad Sharif
authors.initials: MS
authors.lastname: Hossain
authors.affiliation: Infectious Diseases Division, International Centre for Diarrheal Diseases Research, Bangladesh, Mohakhali, Dhaka, Bangladesh.
authors.forename: Mohammad Golam
authors.initials: MG
authors.lastname: Kibria
authors.affiliation: Infectious Diseases Division, International Centre for Diarrheal Diseases Research, Bangladesh, Mohakhali, Dhaka, Bangladesh.
authors.forename: Nusrat
authors.initials: N
authors.lastname: Jahan
authors.affiliation: Infectious Diseases Division, International Centre for Diarrheal Diseases Research, Bangladesh, Mohakhali, Dhaka, Bangladesh.
authors.forename: Wasif A
authors.initials: WA
authors.lastname: Khan
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia.
authors.forename: Kamala
authors.initials: K
authors.lastname: Thriemer
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Chatfield
authors.affiliation: Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia.|Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Ric N
authors.initials: RN
authors.lastname: Price
authors.affiliation: Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria, Australia.|Department of Medicine, University of Melbourne, Parkville, Victoria, Australia.|Victorian Infectious Diseases Service, Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
authors.forename: Jack S
authors.initials: JS
authors.lastname: Richards
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001459:Bangladesh / Q000453:epidemiology; D015374:Biosensing Techniques / Q000295:instrumentation; D002648:Child; D002675:Child, Preschool; D003124:Colorimetry / Q000295:instrumentation; D003430:Cross-Sectional Studies; D019353:Endemic Diseases; D005260:Female; D005954:Glucosephosphate Dehydrogenase / Q000097:blood*; D005955:Glucosephosphate Dehydrogenase Deficiency / Q000097:blood / Q000453:epidemiology* / Q000208:ethnology; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008288:Malaria / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011237:Predictive Value of Tests; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000295:instrumentation; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D005954:Glucosephosphate Dehydrogenase