Folate and vitamin B12 status and predicted neural tube defects risk among nonpregnant women of reproductive age from the Malawi National Micronutrient Survey, 2015-2016.

BACKGROUND: Maternal folate and vitamin B12 deficiency can lead to serious adverse pregnancy outcomes. There are no nationally representative estimates on folate and vitamin B12 status among women of reproductive age (WRA) in Malawi. OBJECTIVE: We assessed folate and vitamin B12 status among nonpregnant WRA in Malawi and predicted the risk of folate-sensitive neural tube defects (NTDs) were they to become pregnant. METHODS: Using data from the cross-sectional, nationally representative 2015-2016 Malawi Micronutrient Survey, we calculated the proportion of folate and vitamin B12 deficiency and insufficiency by demographic characteristics among 778 nonpregnant WRA (15-49 years). We predicted NTD prevalence using red blood cell (RBC) folate distributions and a published Bayesian model of the association between RBC folate and NTD risk. Analyses accounted for complex survey design. RESULTS: Among WRA, 8.5% (95% CI: 6.2, 11.6) and 13.3% (10.0, 17.4) had serum (<7 nmol/L) and RBC folate (<305 nmol/L) deficiency, respectively. The proportion of vitamin B12 deficiency (<148 pmol/L) and insufficiency (≤221 pmol/L) was 11.8% (8.6, 16.0) and 40.6% (34.1, 47.4), respectively. RBC folate insufficiency (<748 nmol/L, defined as the concentration associated with the threshold for elevated NTD risk: >8 cases per 10,000 births) was widespread: 81.4% (75.0, 86.4). The predicted NTD risk nationally was 24.7 cases per 10,000 live births. RBC folate insufficiency and higher predicted NTD risk were more common among WRA living in urban areas or with higher education. CONCLUSIONS: These findings highlight the importance of nutritional and NTD surveillance in Malawi and the opportunity for improving folate and vitamin B12 nutrition among Malawian WRA.

A multicenter analytical performance evaluation of a multiplexed immunoarray for the simultaneous measurement of biomarkers of micronutrient deficiency, inflammation and malarial antigenemia.

A lack of comparative data across laboratories is often a barrier to the uptake and adoption of new technologies. Furthermore, data generated by different immunoassay methods may be incomparable due to a lack of harmonization. In this multicenter study, we describe validation experiments conducted in a single lab and cross-lab comparisons of assay results to assess the performance characteristics of the Q-plex™ 7-plex Human Micronutrient Array (7-plex), an immunoassay that simultaneously quantifies seven biomarkers associated with micronutrient (MN) deficiencies, inflammation and malarial antigenemia using plasma or serum; alpha-1-acid glycoprotein, C-reactive protein, ferritin, histidine-rich protein 2, retinol binding protein 4, soluble transferrin receptor, and thyroglobulin. Validations included repeated testing (n = 20 separately prepared experiments on 10 assay plates) in a single lab to assess precision and linearity. Seven independent laboratories tested 76 identical heparin plasma samples collected from a cohort of pregnant women in Niger using the same 7-plex assay to assess differences in results across laboratories. In the analytical validation experiments, intra- and inter-assay coefficients of variation were acceptable at <6% and <15% respectively and assay linearity was 96% to 99% with the exception of ferritin, which had marginal performance in some tests. Cross-laboratory comparisons showed generally good agreement between laboratories in all analyte results for the panel of 76 plasma specimens, with Lin's concordance correlation coefficient values averaging ≥0.8 for all analytes. Excluding plates that would fail routine quality control (QC) standards, the inter-assay variation was acceptable for all analytes except sTfR, which had an average inter-assay coefficient of variation of ≥20%. This initial cross-laboratory study demonstrates that the 7-plex test protocol can be implemented by users with some experience in immunoassay methods, but familiarity with the multiplexed protocol was not essential.

Vitamin A deficiency has declined in Malawi, but with evidence of elevated vitamin A in children.

BACKGROUND: Reduction of vitamin A deficiency (VAD) in Malawi coincided with introduction of vitamin A-fortified staple foods, alongside continued biannual high-dose vitamin A supplementation (VAS). OBJECTIVE: We describe coverage of vitamin A interventions and vitamin A status in the 2015-2016 Malawi Micronutrient Survey. METHODS: Food samples and biospecimens were collected within a representative household survey across 105 clusters. Retinol was measured using ultraviolet excitation fluorescence (sugar) and photometric determination (oil). Preschool children (PSC, aged 6-59 mo, n = 1102), school-age children (SAC, aged 5-14 y, n = 758), nonpregnant women (n = 752), and men (n = 219) were initially assessed for vitamin A status using retinol binding protein (RBP) and modified relative dose response (MRDR). Randomly selected fasted MRDR participants (n = 247) and nonfasted women and children (n = 293) were later assessed for serum retinol, retinyl esters, and carotenoids. Analyses accounted for complex survey design. RESULTS: We tested sugar and oil samples from 71.8% and 70.5% of the households (n = 2,112), respectively. All of the oil samples and all but one of the sugar samples had detectable vitamin A. National mean retinol sugar and oil contents were 6.1 ± 0.7 mg/kg and 6.6 ± 1.4 mg/kg, respectively. Receipt of VAS in the previous 6 mo was reported by 68.0% of PSC. VAD prevalence (RBP equivalent to <0.7µmol retinol/L) was 3.6% in PSC, and <1% in other groups. One woman and no children had MRDR ≥0.060 indicating VAD. Among fasted PSC and SAC, 18.0% (95% CI: 6.4, 29.6) and 18.8% (7.2, 30.5) had >5% of total serum vitamin A as retinyl esters, and 1.7% (0.0, 4.1) and 4.9% (0.0, 10.2) had >10% of total serum vitamin A as retinyl esters. Serum carotenoids indicated recent intake of vitamin A-rich fruits and vegetables. CONCLUSIONS: Near elimination of VAD in Malawi is a public health success story, but elevated levels of vitamin A among children suggests that vitamin A interventions may need modification.

An Integrated Enhanced Infant and Young Child Feeding (IYCF) and Micronutrient Powder Intervention Improved Select IYCF Practices Among Caregivers of Children Aged 12-23 Months in Eastern Uganda.

BACKGROUND: There is little evidence of the impact of integrated programs distributing nutrition supplements with behavior change on infant and young child feeding (IYCF) practices. OBJECTIVE: We evaluated the impact of an integrated IYCF/micronutrient powder intervention on IYCF practices among caregivers of children aged 12-23 mo in eastern Uganda. METHODS: We used pre-post data from 2 population-based, cross-sectional surveys representative of children aged 12-23 mo in Amuria (intervention) and Soroti (nonintervention) districts (n = 2816). Caregivers were interviewed in June/July at baseline in 2015 and 12 mo after implementation in 2016. We used generalized linear mixed models with cluster as a random effect to calculate the average intervention effect on receiving IYCF counseling, ever breastfed, current breastfeeding, bottle feeding, introducing complementary feeding at age 6 mo, continued breastfeeding at ages 1 and 2 y, minimum meal frequency (MMF), minimum dietary diversity, minimum acceptable diet (MAD), and consumption of food groups the day preceding the survey. RESULTS: Controlling for child age and sex, household wealth and food security, and caregiver schooling, the intervention was positively associated with having received IYCF counseling by village health team [adjusted prevalence difference-in-difference (APDiD): +51.6%; 95% CI: 44.0%, 59.2%]; timely introduction of complementary feeding (APDiD: +21.7%; 95% CI: 13.4%, 30.1%); having consumed organs or meats (APDiD: +9.0%; 95% CI: 1.4%, 16.6%) or vitamin A-rich fruits or vegetables (APDiD: +17.5%; 95% CI: 4.5%, 30.5%); and MMF (APDiD: +18.6%; 95% CI: 11.2%, 25.9%). The intervention was negatively associated with having consumed grains, roots, or tubers (APDiD: -4.4%; 95% CI: -7.0%, -1.7%) and legumes, nuts, or seeds (APDiD: -15.6%; 95% CI: -26.2%, -5.0%). Prevalences of some IYCF practices were low in Amuria at endline including MAD (19.1%; 95% CI :16.3%, 21.9%). CONCLUSIONS: The intervention had a positive impact on several IYCF practices; however, endline prevalence of some indicators suggests a continued need to improve complementary feeding practices.

Relation between Timing of High-Dose Vitamin A Supplementation and Modified-Relative-Dose-Response Values in Children 12-23 Months in Uganda.

BACKGROUND: High-dose vitamin A (VA) supplements (VAS) can temporarily affect VA status. Hence, micronutrient surveys might need to be timed around VAS campaigns to accurately estimate VA deficiency (VAD) prevalence. Little is known about optimal timing of micronutrient surveys when the modified-relative-dose-response (MRDR) is used as a VA indicator. OBJECTIVES: We evaluated the association between days since the end of a VAS campaign and MRDR values in children aged 12-23 mo in Uganda. METHODS: We pooled data from 2 cross-sectional, population-based surveys in eastern Uganda conducted in 2015-2016 (n = 118 children). We estimated the prevalence of VAD (MRDR ≥0.060). Days since the end of a VAS campaign ("days since VAS") was calculated as the interview date minus the end date of the VAS campaign. The MRDR value was assessed using HPLC. We excluded children whose MRDR values were below the limit of detection (<0.007). We used linear regression to evaluate the association between days since VAS and log-transformed MRDR. In adjusted analyses, we controlled for potential confounders. Statistical analyses accounted for the surveys' complex design. RESULTS: The prevalence of VAD was 5.2% (95% CI: 1.1%, 9.3%). Mean days since VAS was 54.1 d (range 39-68 d). Days since VAS was not associated with log-transformed MRDR in unadjusted analyses ($\hat{\beta } = \ $0.0055; 95% CI: -0.009, 0.020; P = 0.45) or adjusted analyses ($\hat{\beta } = $ -0.0073; 95% CI: -0.024, 0.010; P = 0.39). CONCLUSIONS: MRDR measurement through a nutrition survey began as early as 1.3 mo after the end of a VAS campaign in eastern Uganda. Days since the end of a VAS campaign was not associated with MRDR in Ugandan children aged 12-23 mo. Future studies should consider longitudinal designs and evaluate time since VAS and MRDR in children of different ages and in regions with higher VAD prevalence.

Retinol-binding protein, retinol, and modified-relative-dose response in Ugandan children aged 12-23 months and their non-pregnant caregivers.

Retinol-binding protein (RBP), retinol, and modified-relative-dose response (MRDR) are used to assess vitamin A status. We describe vitamin A status in Ugandan children and women using dried blood spot (DBS) RBP, serum RBP, plasma retinol, and MRDR and compare DBS-RBP, serum RBP, and plasma retinol. Blood was collected from 39 children aged 12-23 months and 28 non-pregnant mothers aged 15-49 years as a subsample from a survey in Amuria district, Uganda, in 2016. DBS RBP was assessed using a commercial enzyme immunoassay kit, serum RBP using an in-house sandwich enzyme-linked immunosorbent assay, and plasma retinol/MRDR test using high-performance liquid chromatography. We examined (a) median concentration or value (Q1, Q3); (b) R2 between DBS-RBP, serum RBP, and plasma retinol; and (c) Bland-Altman plots. Median (Q1, Q3) for children and mothers, respectively, were as follows: DBS-RBP 1.15 µmol/L (0.97, 1.42) and 1.73 (1.52, 1.96), serum RBP 0.95 µmol/L (0.78, 1.18) and 1.47 µmol/L (1.30, 1.79), plasma retinol 0.82 µmol/L (0.67, 0.99) and 1.33 µmol/L (1.22, 1.58), and MRDR 0.025 (0.014, 0.042) and 0.014 (0.009, 0.019). DBS RBP-serum RBP R2 was 0.09 for both children and mothers. The mean biases were -0.19 µmol/L (95% limits of agreement [LOA] 0.62, -0.99) for children and -0.01 µmol/L (95% LOA -1.11, -1.31) for mothers. DBS RBP-plasma retinol R2 was 0.11 for children and 0.13 for mothers. Mean biases were 0.33 µmol/L (95% LOA -0.37, 1.03) for children, and 0.29 µmol/L (95% LOA -0.69, 1.27) for mothers. Serum RBP-plasma retinol R2 was 0.75 for children and 0.55 for mothers, with mean biases of 0.13 µmol/L (95% LOA -0.23, 0.49) for children and 0.18 µmol/L (95% LOA -0.61, 0.96) for mothers. Results varied by indicator and matrix. The serum RBP-retinol R2 for children was moderate (0.75), but poor for other comparisons. Understanding the relationships among vitamin A indicators across contexts and population groups is needed.

The Co-Occurrence of Overweight and Micronutrient Deficiencies or Anemia among Women of Reproductive Age in Malawi.

BACKGROUND: In low-resource settings, urbanization may contribute to the individual-level double burden of malnutrition (DBM), whereby under- and overnutrition co-occur within the same individuals. OBJECTIVE: We described DBM prevalence among Malawian women by urban-rural residence, examined whether urban residence was associated with DBM, and assessed whether DBM prevalence was greater than the prevalence expected by chance given population levels of under- and overnutrition, which would suggest DBM is a distinct phenomenon associated with specific factors. METHODS: We analyzed nationally representative data of 723 nonpregnant women aged 15-49 y from the 2015-2016 Malawi Micronutrient Survey. DBM was defined as co-occurring overweight or obesity (OWOB) and ≥1 micronutrient deficiency or anemia. We used Poisson regression models to examine the association between urban residence and DBM and its components. The Rao-Scott modified chi-square test compared the observed and expected DBM prevalence. RESULTS: Nationally, 10.8% (95% CI: 7.0, 14.5) of women had co-occurring OWOB and any micronutrient deficiency and 3.4% (95% CI: 1.3, 5.5) had co-occurring OWOB and anemia. The prevalence of co-occurring OWOB and any micronutrient deficiency was 2 times higher among urban women than rural women [urban 32.6 (24.1, 41.2) compared with rural 8.6 (5.2, 11.9), adjusted prevalence ratio: 2.0 (1.1, 3.5)]. Co-occurring OWOB and anemia prevalence did not significantly differ by residence [urban 6.9 (0.6, 13.2) compared with rural 3.0 (0.8, 5.3)]. There were no statistically significant differences in observed and expected prevalence estimates of DBM. CONCLUSIONS: This analysis shows that co-occurring OWOB and any micronutrient deficiency was higher among women in urban Malawi compared with rural areas. However, our finding that co-occurring OWOB and any micronutrient deficiency or anemia may be due to chance suggests that there may not be common causes driving DBM in Malawian women. Thus, there may not be a need to design and target interventions specifically for women with DBM.

An Integrated Infant and Young Child Feeding and Micronutrient Powder Intervention Does Not Affect Anemia, Iron Status, or Vitamin A Status among Children Aged 12-23 Months in Eastern Uganda.

BACKGROUND: Micronutrient powders (MNP) can reduce iron deficiency and anemia in children. OBJECTIVE: We evaluated the impact of an integrated infant and young child feeding (IYCF)-MNP intervention on anemia and micronutrient status among children aged 12-23 mo in Eastern Uganda. The intervention focused on MNP distribution, IYCF education, and caregiver behavior change. METHODS: Population-based cross-sectional surveys representative of children aged 12-23 mo in Amuria (intervention) and Soroti (nonintervention) districts were collected in June/July 2015 at baseline (n = 1260) and 12 mo after implementation at endline in 2016 (n = 1490). From pooled capillary blood, we assessed hemoglobin, malaria, ferritin, retinol binding protein (RBP), C-reactive protein, and ɑ1-acid glycoprotein. Ferritin and RBP were regression-adjusted to correct for inflammation. Caregivers reported sociodemographic characteristics and MNP knowledge and practices. Linear regression estimated the difference-in-difference (DiD) effect of MNP on hemoglobin, ferritin, and RBP, and logistic regression estimated DiD effect of MNP on anemia (hemoglobin <11.0 g/dL), iron deficiency (ferritin <12.0 µg/L), iron deficiency anemia (hemoglobin <11.0 g/dL and ferritin <12.0 µg/L), and vitamin A deficiency (VAD; RBP equivalent to <0.70 µmol/L retinol: <0.79 µmol/L at baseline and RBP <0.67 µmol/L at endline). RESULTS: In Amuria, 96% of children had ever consumed MNP versus <1% of children in Soroti. Fifty-four percent of caregivers reported organoleptic changes when MNP were added to foods cooked with soda ash. Adjusting for age, sex, malaria, recent morbidity, and household-level factors, the intervention was associated with -0.83 g/dL lower hemoglobin (95% CI, -1.36, -0.30 g/dL; P = 0.003) but not with anemia, ferritin, iron deficiency, iron deficiency anemia, RBP, or VAD. CONCLUSIONS: Despite high program fidelity, the intervention was associated with reduced hemoglobin concentrations but not with change in anemia or micronutrient status among children aged 12-23 mo in Eastern Uganda. Contextual factors, such as cooking with soda ash, might explain the lack of effectiveness.

Predictors of micronutrient powder sachet coverage and recent intake among children 12-23 months in Eastern Uganda.

We evaluated predictors of micronutrient powder (MNP) sachet coverage and recent intake using data from a cross-sectional survey representative of children aged 12-23 months in Amuria district, Uganda. In June/July 2016, caregivers were interviewed 12 months after implementation of an integrated MNP and infant and young child feeding pilot (N = 761). Logistic regression described predictors of (a) high-MNP sachet coverage (received at least 60 sachets/6 months) and (b) recent intake (consumed MNP during the 2 weeks preceding the survey) among children who had ever received MNP and had complete data (N = 683). Fifty-nine percent (95% Confidence Interval [CI] [53.8, 64.2]) of children had high-MNP sachet coverage, and 65.4% (95% CI [61.0, 69.9]) had recent intake. MNP ration cards (Adjusted Odds Ratio [AOR] 2.67, 95% CI [1.15, 6.23]), organoleptic changes to foods cooked with soda ash (AOR 1.52, 95% CI [1.08, 2.14]), having heard of anaemia (AOR 1.59, 95% CI [1.11, 2.26]), knowledge of correct MNP preparation (AOR 1.89, 95% CI [1.11, 3.19]), and current breastfeeding (AOR 2.04, 95% CI [1.36, 3.08]) were positively associated with MNP coverage whereas older child age (18-23 vs. 12-17 months) was inversely associated with coverage (AOR 0.32, 95% CI [0.23, 0.50]). MNP ration cards (AOR 2.86, 95% CI [1.34, 6.09]), having heard an MNP radio jingle (AOR 1.40, 95% CI [1.01, 1.94]), knowledge of correct MNP preparation (AOR 1.88, 95% CI [1.04, 3.39]), and the child not disliking MNP (AOR 1.90, 95% CI [1.13, 3.22]) were positively associated with recent intake. Interventions that increase caregiver knowledge and skills and focus on older children could improve MNP coverage and recent intake.

Methods and analyzers for hemoglobin measurement in clinical laboratories and field settings.

This paper describes and compares methods and analyzers used to measure hemoglobin (Hb) in clinical laboratories and field settings. We conducted a literature review for methods used to measure Hb in clinical laboratories and field settings. We described methods to measure Hb and factors influencing results. Automated hematology analyzer (AHA) was reference for all Hb comparisons using evaluation criteria of ±7% set by College of American Pathologists (CAP) and Clinical Laboratory Improvement Amendments (CLIA). Capillary fingerprick blood usually produces higher Hb concentrations compared with venous blood. Individual drops produced lower concentrations than pooled capillary blood. Compared with the AHA: (1) overall cyanmethemoglobin (1.0-8.0  g/L), WHO Colour Scale (0.5-10.0  g/L), paper-based devices (5.0-7.0  g/L), HemoCue® Hb-201 (1.0-16.0  g/L) and Hb-301 (0.5-6.0  g/L), and Masimo Pronto® (0.3-14.0  g/L) overestimated concentrations; (2) Masimo Radical®-7 both under- and overestimated concentrations (0.3-104.0  g/L); and (3) other methods underestimated concentrations (2.0-16.0  g/L). Most mean concentration comparisons varied less than ±7% of the reference. Hb measurements are influenced by several analytical factors. With few exceptions, mean concentration bias was within ±7%, suggesting acceptable performance. Appropriate, high-quality methods in all settings are necessary to ensure the accuracy of Hb measurements.This paper describes and compares methods and analyzers used to measure hemoglobin (Hb) in clinical laboratories and field settings. With few exceptions, mean concentration bias was within ±7%, suggesting acceptable performance. Appropriate, high-quality methods in all settings are necessary to ensure the accuracy of Hb measurements.

The Quansys multiplex immunoassay for serum ferritin, C-reactive protein, and α-1-acid glycoprotein showed good comparability with reference-type assays but not for soluble transferrin receptor and retinol-binding protein.

The Quansys multiplex (Q-Plex) measures ferritin (Fer), soluble transferrin receptor (sTfR), C-reactive protein (CRP), α-1-acid glycoprotein (AGP), and retinol-binding protein (RBP). We compared Q-Plex results with reference-type assays and evaluated Q-Plex performance. Pearson correlation and Lin's concordance coefficients between the Q-Plex and reference assay were: Fer 0.98 and 0.91, sTfR 0.88 and 0.35, CRP 0.98 and 0.98, AGP 0.82 and 0.81, and RBP 0.68 and 0.31, respectively. The median relative difference between the Q-Plex and reference assay were: Fer -2.4%, sTfR 107%, CRP 0.03%, AGP -1.3%, and RBP 51%. The Q-Plex intra-assay CVs were <5%; the inter-assay CVs were higher: Fer 11%, sTfR 14%, CRP 9.3%, AGP 7.5%, and RBP 19%. EDTA plasma produced 74% higher Q-Plex sTfR concentrations compared to serum. Analyte stability was good for ≤5 freeze-thaw cycles. After adjusting Q-Plex data to the reference assays, sensitivity and specificity were >85% for Fer and CRP; specificity was >85% for sTfR, AGP, and RBP. Using performance criteria derived from biologic variation, Fer, CRP, and AGP met the minimum allowable imprecision (<10.7%, <31.7%, and <8.5%, respectively) and difference from the reference assay (<±7.7%, <±32.7%, and <±10.3%, respectively), while sTfR and RBP exceeded these thresholds (<8.5% and <7.8% for imprecision and <±7.7% and <±12% for difference, respectively). The Q-Plex measures multiple biomarkers simultaneously, is easy to perform, and uses small sample volumes. With some improvements in accuracy and precision (i.e., sTfR and RBP), this assay could be a useful tool for low-resource laboratories conducting micronutrient surveys for epidemiologic screening applications. These findings need to be verified using other populations, particularly those with inadequate micronutrient status.

Integrating micronutrient status assessment into the 2015-2016 Malawi Demographic and Health Survey: A qualitative evaluation.

Demand for national-level micronutrient status data continues to grow, yet little is known about the implementation of different approaches for collecting these data. We conducted an evaluation of the process of linking the 2015-2016 Malawi Demographic and Health Survey (MDHS) and 2015-2016 Malawi Micronutrient Survey (MNS). We conducted 24 in-depth interviews with stakeholders from the Malawi government and international agencies and field staff. Interview questions explored perceptions of what worked and what was challenging during three phases of implementation: preparation; data collection; and data analysis, reporting, and dissemination. Data were analysed using thematic analysis. Results showed that there was strong government interest to integrate the MDHS and MNS. Perceived benefits included potential cost savings and lower respondent burden. However, government and international agency stakeholders did not view the linkage of the surveys to be a fully integrated approach. The lack of full integration produced challenges throughout implementation, such as complex field logistics and duplication in nutrition indicators assessed and reported. Some stakeholders believed integration was not attainable primarily due to timing. The MDHS and MNS were originally designed as stand-alone surveys, and planning for each survey was at an advanced stage once the government sought to integrate the surveys. Additionally, the MNS could not be incorporated as a module within the MDHS given the complexity of the MNS data collection and short timeframe for planning. These findings can inform decisions about implementing the next MNS and may be transferable to other countries that are conducting micronutrient surveys to address data gaps.

Prevalence of inherited blood disorders and associations with malaria and anemia in Malawian children.

In sub-Saharan Africa, inherited causes of anemia are common, but data are limited regarding the geographical prevalence and coinheritance of these conditions and their overall contributions to childhood anemia. To address these questions in Malawi, we performed a secondary analysis of the 2015-2016 Malawi Micronutrient Survey, a nationally and regionally representative survey that estimated the prevalence of micronutrient deficiencies and evaluated both inherited and noninherited determinants of anemia. Children age 6 to 59 months were sampled from 105 clusters within the 2015-2016 Malawi Demographic Health Survey. Hemoglobin, ferritin, retinol binding protein, malaria, and inflammatory biomarkers were measured from venous blood. Molecular studies were performed using dried blood spots to determine the presence of sickle cell disease or trait, α-thalassemia trait, and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Of 1279 eligible children, 1071 were included in the final analysis. Anemia, iron deficiency, and malaria were common, affecting 30.9%, 21.5%, and 27.8% of the participating children, respectively. α-Thalassemia trait was common (>40% of children demonstrating deletion of 1 [33.1%] or 2 [10.0%] α-globin genes) and associated with higher prevalence of anemia (P < .001). Approximately 20% of males had G6PD deficiency, which was associated with a 1.0 g/dL protection in hemoglobin decline during malaria infection (P = .02). These data document that inherited blood disorders are common and likely play an important role in the prevalence of anemia and malaria in Malawian children.

Effects of preanalytical factors on hemoglobin measurement: A comparison of two HemoCue® point-of-care analyzers.

BACKGROUND: In field studies, hemoglobin (Hb) is often measured using a battery-operated, portable HemoCue® hemoglobinometer. METHODS: We compared the performance of 2 HemoCue® models (Hb-201+ and Hb-301) and investigated effects of preanalytical factors on Hb results by simulating unfavorable field conditions. RESULTS: The Hb-301 produced 2.6% higher results compared to the Hb-201+. Hb had to be measured within 1min of filling the Hb-301 cuvette to avoid artificially elevated concentrations (1.3% per min). The Hb-301 cuvettes withstood elevated temperature (37°C) and humidity (72%) for 3weeks, while the Hb-201+ cuvettes degraded within 10min under those conditions. Both cuvette types withstood elevated temperature for 3weeks. Properly-collected venous and capillary blood produced comparable results. Pooled capillary blood produced comparable results to the second and third but not the fourth drop of blood (3.3% lower). Blood could be stored for ≤4days at 10-30°C before Hb-201+ measurement, but only for 1day at 10-23°C before Hb-301 measurement (≤1% change in Hb). CONCLUSIONS: Higher Hb results obtained with the Hb-301 may influence the interpretation of anemia prevalence in health surveys. While the Hb-301 performed better in high humidity conditions, the Hb-201+ provided more user flexibility regarding delayed Hb reading.