Point-of-Care Testing Using Invasive and Non-Invasive Hemoglobinometers: Reliable and Valid Method for Estimation of Hemoglobin among Children 6–59 Months

Abstract

Introduction Globally around 47.4% of children and in India, 58% of children aged 6–59 months are anemic. Diagnosis of anemia in children using accurate technologies and providing adequate treatment is essential to reduce the burden of anemia. Point-of-care testing (POCT) devices is a potential option for estimation of hemoglobin in peripheral and field settings were the hematology analyzer and laboratory services are not available. Objectives To access the validity of the POCTs (invasive and non-invasive devices) for estimation of hemoglobin among children aged 6–59 months compared with hematology analyzer. Methods The study participants were enrolled from the pediatric outpatient department in Haryana, India, from November 2019 to January 2020. Hemoglobin levels of the study participants were estimated in Sahli’s hemoglobinometer and invasive digital hemoglobinometers (DHs) using capillary blood samples. Hemoglobin levels in non-invasive DH were assessed from the finger/toe of the children. Hemoglobin levels measured in POCTs were compared against the venous blood hemoglobin estimated in the hematology analyzer. Results A total of 120 children were enrolled. The mean (SD) of hemoglobin (g/dl) estimated in auto-analyzer was 9.4 (1.8), Sahli’s hemoglobinometer was 9.2 (1.9), invasive DH was 9.7 (1.9), and non-invasive DH was 11.9 (1.5). Sahli’s hemoglobinometer (95.5%) and invasive DH (92.2%) had high sensitivity for the diagnosis of anemia compared with non-invasive DH (24.4%). In contrast, non-invasive DH had higher specificity (96.7%) compared with invasive DH (83.3%) and Sahli’s hemoglobinometer (70%). Invasive DH took the least time (2–3 min) for estimation of hemoglobin per participant, followed by Sahli’s (4–5 min) and non-invasive DH (5–7 min). Conclusion All three POCT devices used in this study are reasonable and feasible for estimating hemoglobin in under-5 children. Invasive DHs are potential POCT devices for diagnosis of anemia among under-5 children, while Sahli’s can be considered as a possible option, where trained and skilled technicians are available. Further research and development are required in non-invasive DH to improve accuracy. Lay summary In India, anemia is a serious public health problem, where 58% of the children aged 6–59 months are anemic. Point-of-care testing (POCT) using digital hemoglobinometers (DHs) has been recommended as one of the key interventions by the Anemia Mukt Bharat program since 2018 in India. These POCT devices are easy to use, less invasive, can be carried to field, require minimal training and results are available immediately. Therefore this study assessed the validity of POCT devices—invasive DH, non-invasive DH and Sahli’s hemoglobinometer among 6–59 months children in facility setting compared with the gold standard hematology analyzer. A total of 120 children under 6–59 months of age were enrolled from the pediatric outpatient department in Haryana, India, from November 2019 to January 2020. The (mean hemoglobin in g/dl) invasive (9.7) and non-invasive DH (11.9) overestimated hemoglobin value, while Sahli’s (9.2) underestimated hemoglobin compared with hematology analyzer (9.4). Invasive DH (92.2%) and Sahli’s hemoglobinometer (95.5%) reported high ability to correctly identify those with anemia compared with non-invasive DH (24.4%). In contrast, non-invasive DH (96.73%) had higher ability to correctly identify those without the anemia compared with invasive DH (83.3%) and Sahli’s (70%).

Correction Equation for Hemoglobin Values Obtained Using Point of Care Tests—A Step towards Realistic Anemia Burden Estimates

“…A subset of study participants from West Bengal enrolled in the CNNS were randomly included in the validation study, which compared venous and capillary hemoglobin. The detailed methodology of these studies is described elsewhere [ 10 , 11 , 12 , 13 ]. Pregnant women (2 studies conducted in 2018 and 2019—dataset A and B) [ 12 , 13 ], 6- to 59-month-old children (1 study conducted in 2019–2022—dataset C) [ 11 ], and 1- to 19-year-old age group (1 study conducted in 2016–2018—dataset D) [ 10 ] were the study participants included in these 4 studies.…”

“…The detailed methodology of these studies is described elsewhere [ 10 , 11 , 12 , 13 ]. Pregnant women (2 studies conducted in 2018 and 2019—dataset A and B) [ 12 , 13 ], 6- to 59-month-old children (1 study conducted in 2019–2022—dataset C) [ 11 ], and 1- to 19-year-old age group (1 study conducted in 2016–2018—dataset D) [ 10 ] were the study participants included in these 4 studies. Uniform exclusion criteria such as the known history of hemoglobinopathies, metabolic disorders, and chronic diseases affecting blood flow were adopted in all four studies.…”

“…Hemoglobin estimation with an automated hematology analyzer (AHA) using venous blood estimates the hemoglobin level accurately, but it requires a laboratory setting and has feasibility issues, especially for field-based assessments [ 7 ]. With advances in healthcare diagnostics, various point-of-care tests (POCT) such as the cyanmethemoglobin method, WHO hemoglobin color scale, red blood cell protoporphyrin method, Sahli’s hemoglobinometer, and digital hemoglobinometers are available for estimation of hemoglobin in field settings [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Though the POCTs mentioned above are easy and feasible to use, the analytical validity of these is relatively suboptimal compared to the gold standard AHAs for hemoglobin estimation [ 8 , 9 , 10 , 11 , 12 , 13 ].…”

“…With advances in healthcare diagnostics, various point-of-care tests (POCT) such as the cyanmethemoglobin method, WHO hemoglobin color scale, red blood cell protoporphyrin method, Sahli’s hemoglobinometer, and digital hemoglobinometers are available for estimation of hemoglobin in field settings [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Though the POCTs mentioned above are easy and feasible to use, the analytical validity of these is relatively suboptimal compared to the gold standard AHAs for hemoglobin estimation [ 8 , 9 , 10 , 11 , 12 , 13 ]. Additionally, the accuracy of POCTs largely depends on the technician’s competence, proper sample collection procedure, and external environmental factors.…”

“…Additionally, the accuracy of POCTs largely depends on the technician’s competence, proper sample collection procedure, and external environmental factors. Studies have reported diverse sensitivity (24% to 90%) and specificity (60–96%) of these POCT devices in the hemoglobin estimation compared to AHA [ 8 , 9 , 10 , 11 , 12 , 13 ]. In the last two decades, digital hemoglobinometers using capillary blood have been widely used as POCT for estimating hemoglobin, especially in large-scale surveys and primary healthcare settings [ 2 , 14 , 15 ].…”