The authors have declared that no competing interests exist. D.I.A.P. is one of the inventors of the IHAT iron supplementation technology, for which she could receive future awards to inventors through the MRC Awards to Inventor scheme. D.I.A.P. has served as a consultant for Vifor Pharma UK, Entia Ltd, Danone Nutritia, UN Food and Agriculture Organization (FAO) and Nemysis Ltd. D.I.A.P. has since moved to full employment with Vifor Pharma UK. S.A.N received a travel award from Entia Ltd. This does not alter our adherence to PLOS ONE policies on sharing data and materials.
Anemia is one of the most impactful nutrient deficiencies in the world and disproportionately affects children in low-resource settings. Point-of-care devices (PoCDs) measuring blood hemoglobin (Hb) are widely used in such settings to screen for anemia due to their low cost, speed, and convenience. Here we present the first iteration of Aptus, a new PoCD which measures Hb and hematocrit (HCT).
To evaluate the accuracy of Aptus and HemoCue® Hb 301 against an automated hematology analyzer (Medonic®) in Gambian children aged 6–35 months and the Aptus’ usage in the field.
Aptus, HemoCue® and Medonic® were compared using venous blood (n = 180), and Aptus and HemoCue® additionally using capillary blood (n = 506). Agreement was estimated using Bland-Altman analysis and Lin’s concordance. Usage was assessed by error occurrence and user experience.
Mean Hb values in venous blood did not significantly differ between Aptus and HemoCue® (10.44±1.05 vs 10.56±0.93g/dl, p>0.05), but both measured higher Hb concentrations than Medonic® (9.75±0.99g/dl, p<0.0001). Lin’s coefficient between Aptus and Medonic® was rc = 0.548, between HemoCue® and Medonic® rc = 0.636. Mean bias between the PoCDs venous measurements was -0.11g/dl with limits of agreement (LoA) -1.63 and 1.40g/dl. The bias was larger for the comparisons between the Medonic® and both Aptus (0.69g/dl, LoA 0.92 and 2.31g/dl) and HemoCue® (0.81g/dl, LoA 0.17 and 1.78g/dl). ROC curves showed an AUC of 0.933 in HemoCue® and 0.799 in Aptus. Capillary Hb was higher with Aptus than HemoCue® (10.33±1.11g/dl vs 10.01±1.07g/dl, p<0.0001). Mean bias was 0.32g/dl with LoA of -1.91 and 2.54g/dl. Aptus‘ usage proved intuitive, yet time-to-results and cuvettes could be improved.
Both PoCDs showed a relatively limited bias but large LoA. Aptus and HemoCue® showed similar accuracy, while both overestimated Hb levels. Aptus showed promise, with its operation unimpaired by field conditions as well as being able to show HCT values.
Anemia is one of the most prevalent nutrient deficiencies worldwide. The most recent data from the World Health Organization (WHO) in 2011 estimate that the prevalence of anemia in children under the age of five is 42.6% worldwide, with the highest prevalence in the African region at 62.3% [
Furthermore, HCT is often used to approximate Hb in low-resource and field settings where direct Hb measurement is not possible or feasible. The correlation of HCT with Hb is, however, not sufficiently consistent [
The Aptus is a novel PoCD certified in accordance with the requirements of the EU Directive for
The HemoCue® has been extensively evaluated and is seen as the standard PoCD for this type of setting [
This paper presents the first comparative pilot study of these devices in LMIC field settings in rural clinics. The study aimed to: (1) compare Hb concentrations measured in venous blood by HemoCue® Hb 301 and Aptus with a gold standard automated hematology analyzer in young children with IDA in a rural and remote community in the Upper River Region of The Gambia; (2) compare the Hb measurements provided by HemoCue® Hb301 and Aptus in capillary blood; (3) determine the usability of Aptus in these settings and 4) highlight potential improvements to the Aptus model used here before a wider global launch. This was an ancillary study embedded within the IHAT-GUT clinical trial (Registration Number: NCT02941081) [
The specifications of the analytical devices used in this study are summarized in
140 × 70 × 160 mm | 78 x 83 x 52 mm | |
500g (incl. batteries) | 96g | |
Analyzer: 0–50°C (32–122°F) | Analyzer: 0–50°C (32–122°F) | |
Cuvettes: unopened 10–40°C (50–104°F); short-term storage (6 weeks) -18–50°C (0–122°F); 12-month open vial stability | Cuvettes: unopened or opened and resealed 0–50°C (32–122°F) | |
- | 0–90% | |
10–40°C (50–104°F) | 5–45°C (41–113°F) | |
- | 0–90% | |
- | < 4500m | |
AC adapter (6v) or 4 AA batteries | Micro USB (5V) or integrated Li-Ion battery | |
Printer and HemoCue® | Micro USB | |
Basic Connect™ including optional barcode scanner | ||
Built-in self-test, optional liquid controls | Internal quality control. Self-Calibration and self-checks before every measurement, optional liquid controls | |
Absorbance measurement of whole blood at an Hb/HbO2 isosbestic point at 506 nm and 880 nm | Centrifugation and photometry at 515 nm, 660 nm and 940nm | |
Factory calibrated against the ICSH method | Hb: Factory calibrated against HiCN method. HCT: Microhematocrit method | |
Capillary, venous (EDTA suitable), arterial whole blood | Capillary, venous (EDTA, Heparin suitable) | |
~10 μL | 4–8 μL | |
0–25.6 g/dL (0–256 g/L, 0–15.9 mmol/L) | Hb: 5–25 g/dl | |
HCT: 0.15–0.75 L/L (15–75%) | ||
< 10 seconds | 60 seconds | |
Analyzer: ~£400 | Analyzer: £250 | |
Consumables: ~£80 per 200 tests | Consumables: £60 per 200 tests |
To assess usability of the Aptus in field settings, a log of error messages as displayed by the Aptus was kept. These included overfilling or underfilling of cuvettes, termination of centrifugation due to tilt or vibrations of the device, and incorrect cuvette placement. These errors, combined with the user experience of the single operator of the Aptus in this study, were used to extrapolate possible improvements for the device in future model versions.
This prospective study was conducted between 8 October and 22 November 2018 and was ancillary to the IHAT-GUT trial conducted in the Bassé government area, Upper River Region (URR), The Gambia [
All subjects were evaluated and screened for IHAT-GUT study eligibility. In the present study, this was a convenience sample of all children enrolled in the IHAT-GUT study and who attended the study clinics at the pre-specified study timepoints for blood collection. In short, participants were otherwise healthy children of 6–35 months with IDA at enrollment, defined as Hb between 7–11 g/dl and serum ferritin below 30 μg/l, from 17 villages in the study area. Exclusion criteria included severe malnutrition, severe anemia, congenital anomalies and diarrhea or dysentery. For a comprehensive list, please refer to the main study protocol [
Ethical approval for this ancillary study to the IHAT-GUT trial [
The IHAT-GUT study protocol defines that on study day 85, venous blood is collected instead of capillary blood. These samples were used in the present study for the comparisons between the PoCDs and the automated hematology analyzer. Venipuncture was performed by the IHAT-GUT study nurses following standardized study protocols. Briefly, the participant’s arm was wiped with 70% ethanol. A 21-gauge Multifly® needle was used for venipuncture. The samples for the Medonic® analysis were collected in an EDTA Microtainer® blood collection tube, which was continuously inverted for 30 seconds immediately after collection, thus far exceeding the recommended minimum of 10 inversions. Immediately after the blood tubes were filled, the needle was removed and the blood that remained in the needle and attached tube systems was drained on a plastic surface to form a large drop, from which both HemoCue® and Aptus samples were collected (gravity method). The EDTA tubes were subsequently transported to the laboratory site at the MRC field station in Bassé in an isolated carrying box containing cooling elements, where they were analyzed with the Medonic® within four hours of collection.
For all other study timepoints, participants visited the study clinics weekly for a finger prick performed by the nurse following standardized study protocol. These capillary blood samples were used for the comparisons between the two PoCDs, HemoCue® and Aptus. We note that the way the finger prick was performed as part of IHAT-GUT differed from what the Aptus manufacturer recommends, i.e. blood was collected from the thumb and slight pressure was applied for the blood drop to form. Briefly, the child’s thumb was wiped with 70% ethanol and pricked with a Sherwood Safety blood lancet. A little pressure was applied to the finger so that a domed drop formed. Capillary blood for both HemoCue® and Aptus was collected from separate drops of blood from the same fingerprick to minimize variability due to the collection technique. The first drop was wiped clean with cotton, the second drop was used for the measurement with the HemoCue®, and the third drop was used for the Aptus measurement by one of two devices. HemoCue® measurements were conducted by one IHAT-GUT study nurse, whereas the Aptus was exclusively operated by the present study lead author. If during screening a measurement was Hb <7 g/dl (the WHO definition of severe anemia) a venous blood sample was taken and analyzed with Medonic within four hours. If this confirmed the field measurement, the child was classified as severely anemic and stopped the study supplementation to receive standard treatment with oral iron syrups, as per Gambian National Guidelines. Therefore, both PoCDs in this study were evaluated for their usefulness as screening tools, while the analyzer served as diagnostic standard. As such, the WHO standard as cut-off was valid for both PoCDs, which is in line with manufacturers’ recommendations. Indeterminate screening results, i.e. an Hb ≥7g/dl, were thus not analyzed with the reference standard as per the IHAT-GUT protocol [
HemoCue®, Aptus and Medonic® Hb measurements were all performed in accordance with the manufacturers’ operating manuals. Results were recorded on the devices and then manually in a notebook. The study nurses also collected further clinical information during field studies as pertaining to the IHAT-GUT study. The nurses, lab staff and the principal investigator performing the Aptus tests were aware of Hb reference values via their biomedical training.
Before each measurement, the Aptus self-calibrates and self-checks during the centrifugation phase to account for environmental influences, such as temperature and humidity. The device is also able to check for underfilling and overfilling, can remove air bubbles by centrifugation, has an internal QC and displays error messages if it fails.
The HemoCue® has an internal quality control “self-test”, which the system performs automatically every time the analyzer is turned on. The test is performed at regular intervals (typically every two hours) if the analyzer remains switched on. If the self-test fails, an error code will be displayed. Additionally, the Eurotrol Hb301 external QC (levels 1 and 2) was used to verify the accuracy of HemoCue® Hb301 devices daily.
For the Medonic®, the external QCs were run at the start of each analysis day. If the QC results were within range, then the study samples were tested. The laboratory supervisor approved the QC results daily. For external quality control, the laboratory participates in an external inter-laboratory proficiency scheme with OneWorld Canada for hematology full blood analysis and has good clinical laboratory practice (GCLP) accreditation by Qualogy Ltd (UK).
Aptus displayed error messages in 7 out of 190 venous blood measurements (4%) and 108 out of 615 capillary blood measurements (17.6%) (
Excluded samples (dashed rectangles), total of Aptus (rounded rectangles) and HemoCue® (rectangles) data points used for the statistical analyses are indicated. For venous blood, both Aptus and HemoCue® samples were taken during venipuncture and matched with the corresponding Medonic® measurement from the same sample tube. For capillary blood, every Aptus data point was matched with the corresponding HemoCue® measurement.
As this study occurred between study day 57 and 113 of the IHAT-GUT trial, some participants had developed severe anemia since the beginning of the study (Tables
Age at enrollment (months) | |
---|---|
Mean (SD) | 19.58 (7.26) |
Median (IQR) | 20 (11) |
Range (min, max) | 6, 35 |
Female | n = 117 |
Male | n = 106 |
Mean Weight-for-Age (SD) | -0.84 (0.83) |
Mean Height-for-Age (SD) | -0.69 (0.87) |
Mean Weight-for-Height (SD) | -0.77 (0.82) |
Mean (SD) | 9.14 (0.91) |
Median (IQR) | 9.15 (1.20) |
Range (min, max) | 6.9, 11.2 |
Mean (SD) | 17.08 (21.99) |
Median (IQR) | 11.75 (14.03) |
Range (min, max) | 0.1, 247.5 |
Aptus Hb (g/dl) | HemoCue® Hb (g/dl) | Medonic® Hb (g/dl) | |
---|---|---|---|
180 | 183 | 183 | |
7.7 | 7.5 | 6.7 | |
9.7 | 10.1 | 9.1 | |
10.4 | 10.6 | 9.8 | |
11.0 | 11.2 | 10.4 | |
13.2 | 13.5 | 13.2 | |
10.44 | 10.56 | 9.75 | |
1.05 | 0.92 | 0.99 | |
0.08 | 0.07 | 0.07 | |
10.29 | 10.43 | 9.61 | |
10.60 | 10.69 | 9.90 | |
53 | 65 | 20 |
Three data outliers were removed for Aptus. PoCD measurements were conducted on blood drops taken from a venous blood sample before it was collected into the EDTA blood tube for the Medonic® measurements.
Sample size for IHAT-GUT was determined as per the published study protocol [
SPSS Statistics version 25 (IBM corp.) was used for data analysis and visualization. Using three times IQR as cutoff, three Aptus measurements (15.4g/dl, 18.5g/dl and 20.7g/dl) from venous blood were considered outliers and removed from further analysis, leaving 180 venous blood measurements for analysis (
A total of 805 samples (190 venous blood and 615 capillary blood) were collected from 223 study participants enrolled in cohort 3 of the IHAT-GUT trial (
Each measurement included in this set of comparisons (
Aptus-HemoCue® (panel A) and Aptus-Medonic® (panel B) comparisons, n = 180; HemoCue®-Medonic® (panel C), n = 183. The frequency of each difference is represented as a % of total measurements. For these comparisons, 151 (83.9%) of values in panel 1, 114 (63.3%) in panel 2 and 127 (69.4%) in panel 3 showed differences in Hb concentration between -1 and 1 g/dl.
Both PoCDs measured significantly greater Hb concentrations than the Hb value obtained by the Medonic® automated hematology analyzer (
Bland-Altman plots for the Hb concentration comparisons in venous blood samples are shown in
Data represents the difference versus the average Hb results between Aptus-HemoCue® (panel A), Aptus-Medonic® (panel B) and HemoCue®-Medonic® (panel C). The solid lines represent the mean difference between the measurements (bias), while the dotted lines indicate the 95% limits of agreement between methods.
The Desirable Biological Variation Database specifications propose a total error allowable (TEa) for Hb of ±4.19% from the true value as acceptable for a device measuring hemoglobin [
Overall, if we consider the commonly used clinically meaningful difference in Hb concentrations of ± 1 g/dl (29), in the Aptus vs HemoCue® comparisons, 83.9% of values fell within this 1 g/dl threshold, for Aptus vs Medonic® this was 63.3% of values and for HemoCue® vs Medonic®, it was 69.4% of values.
Lin’s coefficient analysis plots are shown in
The dotted line represents the 45-degree line of perfect agreement through the origin, while the solid blue line is the line of best fit. As the Aptus-HemoCue® panel 1 (n = 180) and Aptus-Medonic® panel 2 (n = 180) indicate, the Aptus data has a more pronounced spread in both graphs. Furthermore, the line of best fit deviates significantly from the 45-degree line than in the HemoCue®-Medonic® comparison, indicating weaker agreement. Conversely, the spread of data and angle of the line of best fit in the HemoCue®-Medonic® comparison in panel 2 (n = 183) illustrate that agreement between both PoCDs is stronger compared to the Aptus.
A ROC analysis was also conducted on the venous blood comparison. As there was only one confirmed case of severe anemia and the median values across all devices were close to or above the threshold for moderate anemia of 10 g/dl (
HemoCue® (solid line) proved superior to Aptus (dashed line) in accuracy of measuring non-anemia, with an AUC of 0.933 compared to 0.799, respectively.
A total of 506 measurements from 223 children were included in this set of comparisons. Mean Hb concentrations measured in capillary blood by Aptus (10.33±1.11g/dl) and HemoCue® (10.01±1.07g/dl) were statistically different (
Aptus Hb (g/dl) | HemoCue® Hb (g/dl) | Aptus-HemoCue® Hb difference (g/dl) | |
---|---|---|---|
506 | 506 | 506 | |
6.4 | 7.3 | -3.1 | |
9.5 | 9.2 | -0.4 | |
10.4 | 10.0 | 0.3 | |
11 | 10.8 | 1.0 | |
13.6 | 13.4 | 4.5 | |
10.33 | 10.01 | 0.32 | |
1.11 | 1.07 | 1.13 | |
0.05 | 0.05 | 0.05 | |
10.23 | 9.92 | 0.22 | |
10.43 | 10.11 | 0.42 |
Two data outliers for the Aptus were removed. Capillary blood was collected from the same finger prick but measurements were conducted in two independent blood drops.
The Bland-Altman plot for the comparison between the two PoCDs is shown in
Data represents the difference (Aptus–HemoCue®) versus the average Hb results. The solid lines represent the mean difference between the measurements (bias), while the dotted lines indicate the 95% limits of agreement between methods.
The Aptus device proved easily portable and intuitive in use. The two Aptus devices used in this study were sufficient to cover the maximum of 85 participants per day. However, as photometric measurement with Aptus only commences after centrifugation has completed, the time-to-result is significantly longer in Aptus than HemoCue® (
Besides the observation that blood drawing caused some discomfort to the children, the study reported no adverse events related to blood collection (capillary or venous). Abnormal blood results, i.e. severe anemia (Hb<7 g/dl) were identified in 0 samples with HemoCue® and 3 samples with Aptus. As the Aptus comparison was ancillary to the IHAT-GUT study, its results did not trigger a subsequent analysis for severe anemia by Medonic® as would have been the case if severe anemia was identified by HemoCue®. However, during this study there was one identified severe anemia case with Medonic® measurements collected as part of the outcome assessment timepoints. As per IHAT-GUT protocol this participant was discontinued from the IHAT-GUT supplementation and received standard treatment.
The large impact and preventable nature of anemia warrant large scale screen-and-treat efforts, and cost-efficient and accurate PoCDs are a crucial element in this. The Aptus represents a new development by measuring Hb and HCT concentration. This study assessed the accuracy and usability of the new Aptus PoCD and the well-established HemoCue® 301 PoCD against the automated hematology analyzer Medonic® M-series, in an ancillary study to the IHAT-GUT clinical trial set in a community setting in rural The Gambia [
Overall, both PoCDs showed similar levels of agreement with the laboratory analyzer, however Aptus showed slightly lower bias and wider limits of agreement than the HemoCue®. Both PoCDs were shown to overestimate Hb concentration, as has been shown in previous studies with HemoCue® in children in similar settings [
Venous blood measurements exhibited better agreement both between the PoCDs and with the laboratory analyzer in comparison to the agreement observed between the PoCDs in capillary blood. This is in line with previous research that shows PoCD agreement to be inferior in capillary sampling [
The overestimation of Hb concentration by both PoCDs could translate to underestimating anemia rates when these devices are used as the only diagnosis tool. Averaging multiple capillary measurements, either by using multiple cuvettes [
Thus, usability and appropriateness to such settings are important considerations. Whereas the HemoCue® series has long been recommended as standard for field settings in low resource areas due to its portability, cost and user-friendliness [
To our knowledge, this is the first instance in which this Aptus model was tested in high-throughput and low-resource community settings in children. Aptus is far smaller in dimension and lighter than the HemoCue®, making it more portable, and has validated wide ranges of altitude, temperature and humidity. A major advantage of the Aptus is that it measures MCHC and HCT directly. As MCHC has intrinsic diagnostic value, it would be beneficial to have the option to display MCHC directly post-measurement. This is particularly relevant since this study revealed poorer agreement in the HCT values than for the calculated Hb values (Figs
The usage proved intuitive and simple, yet some limitations apply specifically to these settings, namely the longer duration of measurement and difficulty in handling the cuvettes. If the intended use is high-throughput screenings in rural field clinics, then the comparatively longer measurement time due to centrifugation may be a disadvantage in comparison to HemoCue®. A further consideration is that the battery of the Aptus model used was not replaceable and the lack of a consistent power supply for recharging batteries in this type of setting could lead to issues with continuous usage.
Based on field experience and statistical analysis, the Aptus appears comparable in measurement capabilities to the standard of the HemoCue® given the limitations cited. It is stressed that the Aptus results may have been confounded by not adhering strictly to the manufacturer’s specifications. This included the frequent inability to obtain a large dome-shaped blood droplet in the young children, use of the thumb for finger pricking instead of the second or third digit, and squeezing of the finger in order to procure a sufficient amount of blood from the child. This blood sampling procedure is discouraged since the resulting expulsion of interstitial fluid can skew the measurement [
Overall, to improve usability of Aptus in high throughput settings by a wide range of users, experienced or inexperienced, we recommend improvements to both the cuvettes and the timing of the error messages in the device, and the incorporation of additional battery charging capabilities. We note that the Aptus model used in this study is one of the first available commercially and, as a result of this study and feedback from other users, has undergone further development to improve its accuracy, software interface and cuvette handling.
This was the first study of the Aptus device in this type of setting and was intended to inform further development in terms of performance before wider adoption in resource-poor rural areas. Aptus and HemoCue® showed similar accuracy and both overestimated Hb levels, which could lead to an underestimation of anemia prevalence when used as a screening or diagnostic tool. Aptus showed promise with its operation unimpaired by the field clinic’s conditions, but operational limitations concerning duration of measurements may make it less suitable for high-throughput screening. Importantly, the additional diagnostic value of measuring MCHC may make Aptus a superior choice if the improvements highlighted in this study are achieved. Since MCHC analysis was beyond the scope of this paper, future studies should investigate this. By broadening the range of validated PoCDs available to users, we hope that anemia diagnosis and screening programs improve coverage for the benefit of billions of people around the world.
(XLSX)
Macro used in the study to calculate the Lin’s coefficient in SPSS. Available from:
(DOCX)
Measurements in the Aptus were conducted in blood drops taken from a venous blood sample. Al HCT values given as percentage. The mean difference between the methods is 5.11 (95% CI: 4.76, 5.45) %, which was statistically significant (p<0.0001).
(DOCX)
Data represents the difference (Aptus–Medonic®) versus the average HCT results. The solid lines represent the mean difference between the measurements (bias) is 5.1%, while the dotted lines indicate the 95% limits of agreement between methods of 0.5(lower) and 9.71% (upper) limit.
(TIF)
The dotted line represents the 45-degree line of perfect agreement through the origin, while the solid blue line is the line of best fit. Lin’s coefficient is rc = 0.285, and there is significant divergence from the 45-degree line and spread around the line of best fit (S2 Fig). It must be noted that the Aptus® does not provide decimals for HCT while the Medonic® does. This explains the columnar nature of the data in both plots, and negatively influences agreement due to an inherently lower accuracy of the Aptus®’s output.
(TIF)
We would like to sincerely thank all participants and their families for their participation and the local communities for welcoming us to conduct this study. We would like to thank Entia Ltd for supplying the Aptus devices and consumables, for user training, and for reviewing the final draft of this manuscript.
PONE-D-20-03905
Hemoglobin point-of-care testing in rural Gambia: Comparison of HemoCue® and Aptus™ with an automated hematology analyzer
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Reviewer #1: This study aimed to (1) compare Hb concentrations measured in venous blood by 2 PoCDs with an automated analyzer in young children with IDA in a rural setting (2) compare the Hb measurements provided by 2 PoCDs in capillary blood; (3) determine the usability of Aptus in these settings and 4) highlight potential improvements to the Aptus model used here before a wider global launch.
1) The method used for assessing the last two objectives are not well described in article under the "Materials and Method" section
2) The abstract does not include the last 2 aims in it's objectives, nor the results but seems to jump to a conclusion on the use of one PoCD
3) Statistical analysis: It is mentioned in the paper that "The Clinical Laboratory Improvement Amendments (CLIA) of 1988 postulate a ±7% deviance from the true value as acceptable for a device measuring hemoglobin." I think the limit of 7% is very large for hemoglobin measurements. I wish to suggest to the authors to use the total error allowable (TEa) based on Desirable Biological Variation Database specifications. For Hb, this is 4.19%.(
4) I wish to suggest the addition of ROC curves for the 2 PoCDs versus Lab measurements in addition to the agreement analysis
5) The manuscript should follow the Standards for Reporting of Diagnostic Accuracy studies - STARD statement (
6) I think the Conclusion on the usability of Aptus at the end of this manuscript is not fully supported by the results of this study.
7) This study included children. Please kindly specify whether consent was obtained from parents/legal guardians before study procedures
Reviewer #2: The authors of this work present an interesting work which evaluates the performance of 2 Point-of-care devices (PoCDs), Aptus® and HemoCue® against an automated haematology analyser in children in a country with limited resources, The Gambia. These 2 devices showed similar level of agreement with the laboratory analyser but Aptus® showed slightly lower bias and wider limits of agreement than the HemoCue®. Both PoCDs were shown to overestimate Hb concentration. Then, Aptus® could represent an alternative to HemoCue® as standard for field settings in low resource areas.
The study design is clear and the results well presented. I agree with the conclusions and recommendations of this work. However, some clarifications will help to improve the quality of this work.
Introduction
The introduction is clear but would benefit from being more concise.
Table 1 (line 104): would it be possible to have an idea on the prices of these PoCDs, in order to be in agreement with the comment presented on line 369?
Materials and methods
Why the choice of 35 months as the upper limit for the recruitment of children, and not 36 months, even 59 months as in the WHO report (The Global Prevalence of Anaemia in 2011)?
Children with severe anaemia were excluded from this study (line 124). For children between 6 and 59 months of age, WHO defines severe anaemia as <7.0 g / dL. Can you explain why in the basic characteristics of the participants in your study, the minimum haemoglobin level is 6.9 g / dL? (Table 2). Same as in Table 3 where the minimum Hb level for Medonic is 6.7 g / dL?
Results
Do you have climate data (particularly the temperature) at the time the blood samples were taken and the analysis of these samples was performed?
Discussion
The discussion is clear but would benefit from being more concise.
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If you choose “no”, your identity will remain anonymous but your review may still be made public.
Reviewer #1: Yes: Colette Sih
Reviewer #2: Yes: Fernando KEMTA LEKPA
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Dear editors,
We would like to thank the reviewers for their work and have addressed their concerns in the manner described below.
Reviewer #1:
This study aimed to (1) compare Hb concentrations measured in venous blood by 2 PoCDs with an automated analyzer in young children with IDA in a rural setting (2) compare the Hb measurements provided by 2 PoCDs in capillary blood; (3) determine the usability of Aptus in these settings and 4) highlight potential improvements to the Aptus model used here before a wider global launch.
1) The method used for assessing the last two objectives are not well described in article under the "Materials and Method" section
Clarification has been added in lines 98 – 102
2) The abstract does not include the last 2 aims in it's objectives, nor the results but seems to jump to a conclusion on the use of one PoCD
Descriptions have been added to the abstract (lines 8, 11, 20,21,23-24)
3) Statistical analysis: It is mentioned in the paper that "The Clinical Laboratory Improvement Amendments (CLIA) of 1988 postulate a ±7% deviance from the true value as acceptable for a device measuring hemoglobin." I think the limit of 7% is very large for hemoglobin measurements. I wish to suggest to the authors to use the total error allowable (TEa) based on Desirable Biological Variation Database specifications. For Hb, this is 4.19%.(
The CLIA method has been replaced with the proposed TEa method (lines 292-295)
4) I wish to suggest the addition of ROC curves for the 2 PoCDs versus Lab measurements in addition to the agreement analysis
A ROC analysis was added with absence of anemia (Hb ≥ 11g/dl) as binary outcome variable (lines 316 – 326). As explained in the text, severe and moderate anemia were not suitable for comparison due to the low prevalence.
5) The manuscript should follow the Standards for Reporting of Diagnostic Accuracy studies - STARD statement (
Aspects of the text have been adapted to follow STARD guidelines and the checklist has been uploaded separately. We stress, however, that this was an exploratory comparative study and as such the intention was not to exhaustively determine the diagnostic accuracy of the PoCDs. Furthermore, the ancillary nature of this study necessitated adherence to IHAT-GUT study protocol, which was not planned as a comparative study between the devices and as such did not always represent the optimal study design for such a study.
6) I think the Conclusion on the usability of Aptus at the end of this manuscript is not fully supported by the results of this study.
In order to address this, the usage experience with the Aptus device has been moved from the Discussion to the Results section (lines 353-373), and the Discussion adapted to more clearly highlight the combination of statistical analysis and user experience that our conclusion is based on.
7) This study included children. Please kindly specify whether consent was obtained from parents/legal guardians before study procedures
Consent details have been specified (lines 132-143)
Reviewer #2:
The authors of this work present an interesting work which evaluates the performance of 2 Point-of-care devices (PoCDs), Aptus® and HemoCue® against an automated haematology analyser in children in a country with limited resources, The Gambia. These 2 devices showed similar level of agreement with the laboratory analyser but Aptus® showed slightly lower bias and wider limits of agreement than the HemoCue®. Both PoCDs were shown to overestimate Hb concentration. Then, Aptus® could represent an alternative to HemoCue® as standard for field settings in low resource areas. The study design is clear and the results well presented. I agree with the conclusions and recommendations of this work. However, some clarifications will help to improve the quality of this work.
Introduction
1) The introduction is clear but would benefit from being more concise.
Parts of the Introduction have been reformulated in a more concise way, see tracked changes.
2) Table 1 (line 104): would it be possible to have an idea on the prices of these PoCDs, in order to be in agreement with the comment presented on line 369?
Prices have been added to the last row of table 1 (line 104).
Materials and methods
3) Why the choice of 35 months as the upper limit for the recruitment of children, and not 36 months, even 59 months as in the WHO report (The Global Prevalence of Anaemia in 2011)?
Use of 35 months cut-off (inclusive, we could also write 6 to <36 months) is because this inclusion criteria was for children under the age of 3 years old which has been the group used in the iron supplementation trials conducted in sub-Saharan Africa showing a potential detrimental effect of iron supplementation in infection and diarrhea. We could have used the under 5s as defined by WHO (up to 59 months) but the trials with iron have been focusing on under 35months. Furthermore, after 3 years the microbiome changes too close to an adult-like microbiome and impact of iron on microbiome was an important endpoint of IHAT-GUT and the hypothesis behind IHAT. You can reference:
and
4) Children with severe anaemia were excluded from this study (line 124). For children between 6 and 59 months of age, WHO defines severe anaemia as <7.0 g / dL. Can you explain why in the basic characteristics of the participants in your study, the minimum haemoglobin level is 6.9 g / dL? (Table 2). Same as in Table 3 where the minimum Hb level for Medonic is 6.7 g / dL?
Children had Hb ≥7 g/dL measured by the Medonic at the time of screening and enrolment in the study. The data presented in this manuscript was collected from study day 57 onwards, at which point some children had shown a drop of Hb to below the severe anemia cut-off. These children were subsequently discontinued of the study supplementation, as per IHAT-GUT study protocol, and given standard of care iron drops according to national guidelines in The Gambia. As this clinical consequence does not interfere with the methodological comparison of the measuring devices, these measurements were not excluded in the present study.
For clarification, this explanation was added to the Methods section (lines 170-179, 217-222)
Results
5) Do you have climate data (particularly the temperature) at the time the blood samples were taken and the analysis of these samples was performed?
Temperature and humidity averages added (line 110,111).
Discussion
6) The discussion is clear but would benefit from being more concise.
Parts of the Discussion have been reformulated in a more concise way, see tracked changes. Furthermore, the description of the Aptus in-field usage has been moved to the Results section (lines 353-373), thereby significantly shortening the Discussion.
Academic Reviewer
1. PLOS ONE's style requirements, including those for file naming.
File names have been amended, Panels in figures 2-4 combined into planes, line numbers added to the title page and minor formatting issues fixed in the main text.
2. Competing interests and funding statements
Competing interests and funding statements have been amended and clarified as per the feedback received.
3. Figures
All figure files have been checked with Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool.
We believe the manuscript is now suitable for publication in your journal.
Kind regards,
Stefan Nass
On behalf of all the authors
Submitted filename:
PONE-D-20-03905R1
Hemoglobin point-of-care testing in rural Gambia: Comparing accuracy of HemoCue® and Aptus™ with an automated hematology analyzer
PLOS ONE
Dear Dr. Nass,
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Reviewers' comments:
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Reviewer #1: All comments have been addressed
Reviewer #2: All comments have been addressed
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Reviewer #1: Yes
Reviewer #2: Yes
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3. Has the statistical analysis been performed appropriately and rigorously?
Reviewer #1: Yes
Reviewer #2: Yes
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The
Reviewer #1: No
Reviewer #2: Yes
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Reviewer #2: Yes
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Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)
Reviewer #1: The aim of this study was to (1) compare Hb concentrations measured in venous blood by 2 PoCDs with an
automated analyzer in young children with IDA in a rural setting (2) compare the Hb
measurements provided by 2 PoCDs in capillary blood; (3) determine the usability of Aptus in these
settings and 4) highlight potential improvements to the Aptus model used here before a wider
global launch.
1) A considerable amount of grammatical errors noted with additional "the", "a", sentences which are too long making their comprehension difficult
Reviewer #2: Dear Editor,
We have read the new version of the article submitted for our review by Nass S. et al on “ Hemoglobin point-of-care testing in rural Gambia: Comparing accuracy of HemoCue® and Aptus™ with an automated hematology analyzer”.
The authors have taken all of my comments into consideration.
We have no new comments.
Best regards
fkl
**********
7. PLOS authors have the option to publish the peer review history of their article (
If you choose “no”, your identity will remain anonymous but your review may still be made public.
Reviewer #1:
Reviewer #2:
[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]
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Dear editors,
We would like to thank the reviewers for their work and have addressed their concerns in the manner described below.
Reviewer #1:
1) A considerable amount of grammatical errors noted with additional "the", "a", sentences which are too long making their comprehension difficult
The manuscript has been reviewed again by three native speakers. For the revisions, see tracked changes.
4. Have the authors made all data underlying the findings in their manuscript fully available? Answer: No
The reviewer has not further specified which data they are referring to. All data pertaining to this analysis is presented in the manuscript. The demographic and endpoint data for the IHAT-GUT trial will be published separately and the full database for the IHAT-GUT trial will be made available upon publication of the primary and secondary endpoints. We trust that this is sufficient with regards to the data policy.
We believe the manuscript is now suitable for publication in your journal.
Kind regards,
Stefan Nass
On behalf of all the authors
Submitted filename:
Hemoglobin point-of-care testing in rural Gambia: Comparing accuracy of HemoCue® and Aptus™ with an automated hematology analyzer
PONE-D-20-03905R2
Dear Dr. Nass,
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Simeon-Pierre Choukem
Academic Editor
PLOS ONE
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Reviewers' comments:
PONE-D-20-03905R2
Hemoglobin point-of-care testing in rural Gambia: Comparing accuracy of HemoCue and Aptus with an automated hematology analyzer
Dear Dr. Nass:
I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.
If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact
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