80 100 120 140 160 Sysmex (Hb, g/L) 80 100 120 140 160 Hemocue (Hb, g/L) reduced major axis line of perfect concordance Women with other Hb variants (n=92) C 80 100 120 140 160 Sysmex (Hb, g/L) 80 100 120 140 160 Hemocue (Hb, g/L) reduced major axis line of perfect concordance Women with Hb E variants (n=133) B 80 100 120 140 160 Sysmex (Hb, g/L) 80 100 120 140 160 Hemocue (Hb, g/L) reduced major axis line of perfect concordance Women with no genetic Hb disorder (n=195) A -15 22 0 Difference of Sysmex and Hemocue (Hb, g/L) 90 100 110 120 130 140 Mean of Sysmex and Hemocue (Hb, g/L) observed average agreement 95% limits of agreement Women with other Hb variants (n=92) C -26 23 0 Difference of Sysmex and Hemocue (Hb, g/L) 90 100 110 120 130 140 Mean of Sysmex and Hemocue (Hb, g/L) observed average agreement 95% limits of agreement Women with Hb E variants (n=133) B -26 27 0 Difference of Sysmex and Hemocue (Hb, g/L) 100 120 140 160 Mean of Sysmex and Hemocue (Hb, g/L) observed average agreement 95% limits of agreement Women with no genetic Hb disorder (n=195) A In Cambodia, genetic hemoglobin (Hb) disorders affect ~50% of the population, the most common of which are Hb E variants. 1,2 Hb E variants cause an altered structure of the β-globin chain of Hb resulting in an unstable Hb molecule. 3,4 The gold standard in Hb measurement is the automated hematology analyzer 5 , however it is not always feasible in rural field settings or in large surveys. Portable hemoglobinometers, such as the Hemocue, have become increasingly popular as they are easy to use, inexpensive, and provide an immediate Hb reading. 6 No known studies have investigated whether the Hemocue is as accurate as the gold standard hematology analyzer in measuring Hb among individuals with these unstable Hb E variants. Our objective was to determine the bias (difference in means) and concordance between Hemocue and Sysmex among 420 non-pregnant Cambodian women (18-45 y) and to determine if there were differences in Hb measurement among women with Hb E variants. An Evaluation of Two Methods to Measure Hemoglobin Concentration among Women with Genetic Hemoglobin Disorders in Cambodia BACKGROUND & OBJECTIVE Crystal Karakochuk 1 , Amynah Janmohamed 1 , Kyly Whitfield 1 , Susan Barr 1 , Suzanne Vercauteren 2 , Hou Kroeun 3 , Zaman Talukder 3 , Judy McLean 1 , Tim Green 1 1 Food, Nutrition and Health, University of British Columbia, Vancouver, Canada, 2 Division of Hematopathology, BC Children’s Hospital, Vancouver, Canada, 3 Helen Keller International, Cambodia RESULTS SUMMARY & CONCLUSIONS § Bias and concordance were similar among all three genotype sub-groups, suggesting that the Hemocue and Sysmex methods were comparable in measuring Hb among women with no Hb variants, women with Hb E variants and women with other Hb variants (not including Hb E). § In the concordance plots (Fig. 2), the Hemocue appears to underestimate Hb concentration at lower concentrations and overestimate Hb concentration at higher Hb concentrations. This could result in false positives in the individual diagnosis of anemia when using the Hemocue. § Even a small bias between methods can have a significant impact on anemia prevalence rates. In our case, a bias of 2.6 g/L resulted in a 11.5% difference in anemia prevalence (41.0% vs. 29.5%, p<0.05), changing the WHO classification from a ‘severe’ to ‘moderate’ public health problem. § The Hemocue is a practical and inexpensive device to measure Hb in field settings, however we caution researchers and policy makers in the interpretation of data and suggest when possible to measure Hb in a sub-sample using a second method to confirm the accuracy of measurement. 1. Carnley BP, et al. Hemoglobin 2006; 30: 463-70. 2. Karakochuk CD, et al. J Nutr 2015; 145: 134-42. 3. Frischer H et al. J Lab Clin Med 1975; 85: 531-9. 4. Yuthavong Y, et al. J Med Assoc 1975; 58: 351-6. We gratefully acknowledge the women who participated in the study. We thank the Cambodian Ministry of Health and Helen Keller International for their collaboration and support. C.K. was funded by a CIHR Vanier Scholarship. The project was funded by the International Development Research Centre (IDRC), and the Government of Canada, provided through Foreign Affairs, Trade and Development (DFATD). For more information please contact: Crystal.Karakochuk@alumni.ubc.ca Scan the QR code to access the publication: Karakochuk CD, et al. Clin Chem Acta 2015; 148-155. METHODS Figure 1. Bias and Precision Plots among Women by Genotype Sub-group This study used secondary data collected in June 2012. Genetic Hb disorders were determined using Hb gel electrophoresis (Sebia MINICAP) and a multiplex PCR assay. 2 We compared Hb measurements using two methods: Ø Hemocue Hb 201+ - a hemoglobinometer using capillary blood Ø Sysmex XT-1800i - an automated hematology analyzer using venous blood Bland & Altman’s bias and precision 6 and Lin’s concordance coefficient 7 were calculated and plotted among women by genotype sub-group using STATA SE/13.1 software for Mac. Table 1. Hemoglobin Concentration, Anemia Prevalence, Bias, Precision and Concordance between Hemocue and Sysmex Methods Population Group Number n (%) Hb Concentration mean g/L ±SD Anemia Prevalence a n (%) Bias g/L ±SEM Precision ±1.96 SD Concordance ρ c Hemocue Sysmex Hemocue Sysmex All Women 420 (100) 121.9 ±13.3 124.5 ±10.9 172 (41.0)* 124 (29.5)* 2.6 ±0.4 -13.1, 18.2 0.77 A: Women with no Hb disorders 195 (46) 127.0 ±11.9 129.5 ±8.9 46 (23.6)* 22 (11.3)* 2.5 ±0.6 -13.5, 18.5 0.68 B: Women with Hb E variants b 133 (32) 117.4 ±12.9 119.8 ±10.7 74 (55.6) 69 (51.9) 2.5 ±0.7 -12.5, 17.5 0.78 C: Women with other Hb variants c 92 (22) 117.8 ±12.7 120.7 ±10.3 52 (56.5)* 33 (35.9)* 2.7 ±0.8 -13.0, 18.7 0.73 a Based on Hb <120 g/L for non-pregnant women of reproductive age. 6 Hb, hemoglobin; SD, standard deviation; SEM, standard error of the mean. b Includes women with Hb E variants (homozygosity and heterozygosity) and/or any other co-inherited variant. c Includes women with Hb CS variants, α- or β-thalassemia, or other rare Hb variants (not including Hb E variants). *Pearson’s chi-square test showed a statistically significant difference in anemia prevalence between Hemocue and Sysmex methods (p<0.05). Figure 2. Concordance Plots among Women by Genotype Sub-group 5. Fujimoto K. Sysmex J Int 1999; 9: 31-44. 6. WHO/CDC. 2 nd ed. Geneva: WHO; 2007. 7. Bland JM et al. Lancet 1986; 8: 307-17. 8. Lin LI. Biometrics 1989; 45: 255-68. RESULTS REFERENCES ACKNOWLEDGMENTS View publication stats View publication stats