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Journal Articles PLoS Medicine Year : 2020

Quantification of glucose-6-phosphate dehydrogenase activity by spectrophotometry: A systematic review and meta-analysis

1 Menzies School of Health Research [Australia]
2 Big Data Institute - Nuffield Department of Medicine [Oxford, UK]
3 University of Cape Coast [Ghana]
4 International Center for Diarrheal Disease Research [Mohakhali, Bangladesh]
5 PATH [Seattle]
6 MUST - Mbarara University of Science and Technology [Mbarara]
7 Epicentre Ouganda [Mbarara] [Médecins Sans Frontières]
8 FMT-HVD - Fundação de Medicina Tropical Doutor Heitor Vieira Dourado
9 CMU - Chiang Mai University
10 Curtin University [Perth]
11 Penn State - Pennsylvania State University
12 KMUST - Kunming University of Science and Technology
13 University of Jos [Nigeria]
14 Research Institute for Tropical Medicine [Muntinlupa City, Philippines]
15 George Mason University [Fairfax]
16 University of Khartoum
17 LSHTM - London School of Hygiene and Tropical Medicine
18 Laboratoire d'épidémiologie moléculaire
19 AFRIMS - Armed Forces Research Institute of Medical Sciences [Bangkok]
20 AAU - Addis Ababa University
21 Génétique du paludisme et résistance - Malaria Genetics and Resistance
22 Mahidol Oxford Tropical Medicine Research Unit
23 Department of Medical Research (Lower Myanmar) [Yangon]
24 Chulalongkorn University [Bangkok]
25 YSPH - Yale School of Public Health
26 Universitas Sumatera Utara
27 YPKMP - Yayasan Pengembangan Kesehatan dan Masyarakat Papua
28 Melbourne School of Population and Global Health [Melbourne]
29 The Peter Doherty Institute for Infection and Immunity [Melbourne]
30 Malaria Consortium [Phnom Penh, Cambodge]
31 UC San Francisco - University of California [San Francisco]
32 USUHS - Uniformed Services University of the Health Sciences
33 UI - University of Indonesia
34 FIU - Florida International University [Miami]
35 MORU - Mahidol Oxford Tropical Medicine Research Unit
36 Eijkman Institute for Molecular Biology [Jakarta]
37 Nuffield Department of Clinical Medicine [Oxford]
Rosalind Howes
  • Function : Author
  • PersonId : 948719
Pooja Bansil
  • Function : Author
Liwang Cui
  • Function : Author
  • PersonId : 926713
Nimol Khim
  • Function : Author
  • PersonId : 917374
Sampa Pal
  • Function : Author
Gonzalo J Domingo
  • Function : Author

Abstract

Background: The radical cure of Plasmodium vivax and P. ovale requires treatment with primaquine or tafenoquine to clear dormant liver stages. Either drug can induce haemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, necessitating screening. The reference diagnostic method for G6PD activity is ultraviolet (UV) spectrophotometry; however, a universal G6PD activity threshold above which these drugs can be safely administered is not yet defined. Our study aimed to quantify assay-based variation in G6PD spectrophotometry and to explore the diagnostic implications of applying a universal threshold. Methods and findings: Individual-level data were pooled from studies that used G6PD spectrophotometry. Studies were identified via PubMed search (25 April 2018) and unpublished contributions from contacted authors (PROSPERO: CRD42019121414). Studies were excluded if they assessed only individuals with known haematological conditions, were family studies, or had insufficient details. Studies of malaria patients were included but analysed separately. Included studies were assessed for risk of bias using an adapted form of the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Repeatability and intra- and interlaboratory variability in G6PD activity measurements were compared between studies and pooled across the dataset. A universal threshold for G6PD deficiency was derived, and its diagnostic performance was compared to site-specific thresholds. Study participants (n = 15,811) were aged between 0 and 86 years, and 44.4% (7,083) were women. Median (range) activity of G6PD normal (G6PDn) control samples was 10.0 U/g Hb (6.3-14.0) for the Trinity assay and 8.3 U/g Hb (6.8-15.6) for the Randox assay. G6PD activity distributions varied significantly between studies. For the 13 studies that used the Trinity assay, the adjusted male median (AMM; a standardised metric of 100% G6PD activity) varied from 5.7 to 12.6 U/g Hb (p < 0.001). Assay precision varied between laboratories, as assessed by variance in control measurements (from 0.1 to 1.5 U/g Hb; p < 0.001) and study-wise mean coefficient of variation (CV) of replicate measures (from 1.6% to 14.9%; p < 0.001). A universal threshold of 100% G6PD activity was defined as 9.4 U/g Hb, yielding diagnostic thresholds of 6.6 U/g Hb (70% activity) and 2.8 U/g Hb (30% activity). These thresholds diagnosed individuals with less than 30% G6PD activity with study-wise sensitivity from 89% (95% CI: 81%-94%) to 100% (95% CI: 96%-100%) and specificity from 96% (95% CI: 89%-99%) to 100% (100%-100%). However, when considering intermediate deficiency (<70% G6PD activity), sensitivity fell to a minimum of 64% (95% CI: 52%-75%) and specificity to 35% (95% CI: 24%-46%). Our ability to identify underlying factors associated with study-level heterogeneity was limited by the lack of availability of covariate data and diverse study contexts and methodologies. Conclusions: Our findings indicate that there is substantial variation in G6PD measurements by spectrophotometry between sites. This is likely due to variability in laboratory methods, with possible contribution of unmeasured population factors. While an assay-specific, universal quantitative threshold offers robust diagnosis at the 30% level, inter-study variability impedes performance of universal thresholds at the 70% level. Caution is advised in comparing findings based on absolute G6PD activity measurements across studies. Novel handheld quantitative G6PD diagnostics may allow greater standardisation in the future.
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pasteur-02865146 , version 1 (11-06-2020)

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CC0 - Public Domain Dedication

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Daniel Pfeffer, Benedikt Ley, Rosalind Howes, Patrick Adu, Mohammad Shafiul Alam, et al.. Quantification of glucose-6-phosphate dehydrogenase activity by spectrophotometry: A systematic review and meta-analysis. PLoS Medicine, 2020, 17 (5), pp.e1003084. ⟨10.1371/journal.pmed.1003084⟩. ⟨pasteur-02865146⟩
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