An evidence-based definition of anemia for singleton, uncomplicated pregnancies.

BACKGROUND: The definition for anemia in pregnancy is outdated, derived from Scandinavian studies in the 1970's to 1980's. To identity women at risk of blood transfusion, a common cause of Severe Maternal Morbidity, a standard definition of anemia in pregnancy in a modern, healthy United States cohort is needed. OBJECTIVE: To define anemia in pregnancy in a United States population including a large county vs. private hospital population using uncomplicated patients. MATERIALS AND METHODS: Inclusion criteria were healthy women with the first prenatal visit before 20 weeks. Exclusion criteria included preterm birth, preeclampsia, hypertension, diabetes, short interval pregnancy (<18 months), multiple gestation, abruption, and fetal demise. All women had iron fortification (Ferrous sulfate 325 mg daily) recommended. The presentation to care and pre-delivery hematocrits were obtained, and the percentiles determined. A total of 2000 patients were included, 1000 from the public county hospital and 1000 from the private hospital. Each cohort had 250 patients in each 2011, 2013, 2015, and 2018. The cohorts were compared for differences in the fifth percentile for each antepartum epoch. Student's t-test and chi-squared statistical tests were used for analysis, p-value of ≤0.05 was considered significant. RESULTS: In the public and private populations, 777 and 785 women presented in the first trimester while 223 and 215 presented in the second. The women at the private hospital were more likely to be older, Caucasian race, nulliparous, and present earlier to care. The fifth percentile was compared between the women in the private and public hospitals and were clinically indistinguishable. When combining the cohorts, the fifth percentile for hemoglobin/hematocrit was 11 g/dL/32.8% in the first trimester, 10.3 g/dL/30.6% in the second trimester, and 10.0 g/dL/30.2% pre-delivery. CONCLUSIONS: Fifth percentile determinations were made from a combined cohort of normal, uncomplicated pregnancies to define anemia in pregnancy. Comparison of two different cohorts confirms that the same definition for anemia is appropriate regardless of demographics or patient mix.

Eliminating race-based reference ranges in haematology: a call to action.

In haematology, as in all of medicine, the use of reference intervals for laboratory variables is essential to define disease states and inform treatment decisions. There are many haematological variables, including haemoglobin, mean corpuscular volume, absolute neutrophil count, and iron indices, that are often reported to be different on the basis of a person's race or ethnicity. Although there are many haematological conditions with a genetic basis, such that it is appropriate to consider ancestry in the diagnostic algorithm, defining pathology on the basis of a social construct such as race is unacceptable. The inclusion of separate thresholds or simple statements that so-called normal values vary by race further validates the common misperception that there are physiological differences between Black and white patients. These statements might have downstream effects on diagnostic and treatment decisions that exacerbate existing racial health disparities. In this Viewpoint, we argued for the removal of race-based reference intervals across haematology.

Clinical laboratory hematology reference values among infants aged 1month to 17 months in Kombewa Sub-County, Kisumu: A cross sectional study of rural population in Western Kenya.

There is an urgent need for reliable region-specific hematological reference values for clinical monitoring. Laboratory reference ranges are important for assessing study participant eligibility, toxicity grading and management of adverse events in clinical trials and clinical diagnosis. Most clinical laboratories in Kenya rely on hematological reference values provided by instrument manufacturers and/or textbooks, which are based on population from Europe or North America. The use of such values in medical practice could result in improper patient management, selection bias in selection of appropriate participants for clinical trials and flawed classification of the clinical adverse events when applied to African populations. The aim of this study was to establish local laboratory hematological reference values in infants aged 1 month to 17 months from Kombewa Sub-county that could be true representative of the existing rural population. The study participants in the current study were those who had previously been recruited from GSK-sponsored study. This study was a phase III, Double Blind, Randomized, GSK-sponsored, Malaria Vaccine Clinical Trial that was conducted in infants aged 1month to 17months. 1,509 participants were included in the study analysis. Data were partitioned into 3 different age groups (1-6 months[m], 6-12 m and 12-17 m) and differences between gender were compared within each group. Data were analyzed using Graphpad prism V5 to generate 95% reference ranges (2.5th-97.5th percentile). There was evidence of gender differences in hemoglobin values (p = 0.0189) and platelet counts (p = 0.0005) in the 1 to 6m group. For the 12-17m group, there were differences in MCV (p<0.0001) and MCH (p = 0.0003). Comparing gender differences for all age groups, differences were noted in percent lymphocytes (p = 0.0396), percent monocytes (p = 0.0479), percent granulocytes (p = 0.0044), hemoglobin (p = 0.0204), hematocrit (p = 0.0448), MCV (p = 0.0092), MCH (p = 0.0089), MCHC (p = 0.0336) and absolute granulocytes (p = 0.0237). In 1 to 6m age group and all age groups assessed, for WBCs, hemoglobin, hematocrit, MCV and lymphocytes absolute counts, both 2.5th and 97.5th percentiles for Kisumu infants were higher than those from Kilifi. Platelet ranges for Kisumu children were narrower compared to Kilifi ranges. Kisumu hematology reference ranges were observed to be higher than the ranges of Tanzanian children for the WBCs, absolute lymphocyte and monocyte counts, hemoglobin, hematocrit and MCV. Higher ranges of WBCs, absolute lymphocyte and monocyte counts were observed compared to the values in US/Europe. Wider ranges were observed in hemoglobin, hematocrit, and MCV. Wider ranges were observed in platelet counts in Kisumu infants compared to the US/Europe ranges. Compared to Harriet Lane Handbook reference values that are used in the area, higher counts were observed in WBC counts, both absolute and percent lymphocyte counts, as well as monocyte counts for current study. Wider ranges were observed in RBC, platelets and RDW, while lower ranges noted in the current study for hemoglobin, hematocrit and granulocyte counts. This study underscores the importance of using locally established hematology reference ranges of different age groups in support of proper patient management and for clinical trials.

Latent class distributional regression for the estimation of non-linear reference limits from contaminated data sources.

BACKGROUND: Medical decision making based on quantitative test results depends on reliable reference intervals, which represent the range of physiological test results in a healthy population. Current methods for the estimation of reference limits focus either on modelling the age-dependent dynamics of different analytes directly in a prospective setting or the extraction of independent distributions from contaminated data sources, e.g. data with latent heterogeneity due to unlabeled pathologic cases. In this article, we propose a new method to estimate indirect reference limits with non-linear dependencies on covariates from contaminated datasets by combining the framework of mixture models and distributional regression. RESULTS: Simulation results based on mixtures of Gaussian and gamma distributions suggest accurate approximation of the true quantiles that improves with increasing sample size and decreasing overlap between the mixture components. Due to the high flexibility of the framework, initialization of the algorithm requires careful considerations regarding appropriate starting weights. Estimated quantiles from the extracted distribution of healthy hemoglobin concentration in boys and girls provide clinically useful pediatric reference limits similar to solutions obtained using different approaches which require more samples and are computationally more expensive. CONCLUSIONS: Latent class distributional regression models represent the first method to estimate indirect non-linear reference limits from a single model fit, but the general scope of applications can be extended to other scenarios with latent heterogeneity.

Consensus minimum hemoglobin level above which patients with myelodysplastic syndromes can safely forgo transfusions.

The anemia of MDS often results in decreased quality of life, which is invoked to justify red cell transfusions; however, there are sparse data regarding the minimum hemoglobin (Hb) at which it is safe to forgo transfusions for patients with no evidence of end-organ damage. This issue is even more important in the COVID-19 era, where decreases in blood donations have stressed the blood supply. In March 2018, using a modified Delphi method, we convened a panel of 13 expert MDS clinicians for three iterative rounds to discuss a minimum safe Hb for this population. While the panel was unable to reach the pre-set consensus of 75% for a specific Hb threshold, there was 100% consensus that it be no greater than 7.5 g/dL. Our data suggest that, given no end-organ effects of anemia, patients with MDS can safely forgo transfusions with a Hb of 7.5 g/dL or higher.

Total haemoglobin - a reference measuring system for improvement of standardisation.

Background Total haemoglobin (Hb) concentration in blood belongs to the most requested measurands, and the HiCN method (hemiglobincyanide) is accepted as a reference. Although the reaction principle is clearly characterised, measurement conditions and settings are not consistently defined, some of them influencing the results. An improvement of standardisation is the object. Methods After method optimization, measurement results between different calibration laboratories (CL) were compared with each other and also with results of the National Metrology Institute of Germany (PTB), with target values of certified reference material, within the RELA scheme, and to >1500 results from routine laboratories. Results Overall deviations between three CLs were ≤0.5% (n = 24 samples) in a measurement range of 20 g/L to 300 g/L. A CV of 0.4% was determined in pooled blood (1 year long-term imprecision, 99.0%-101.1% recovery of the mean). For selected measurements (n = 4 samples) the PTB participated without significant differences to three CLs, and no significant differences were observed comparing CLs to certified values of reference materials. The expanded measurement uncertainty (probability 95%) was estimated as 1.1%. Conclusions A reference measuring system, comprising measuring instruments and other devices, including reagents and supply, to generate reference measurement values for total Hb concentration of high accuracy and low measurement uncertainty is presented. Measurement parameters are investigated and defined. The reference measuring system is ready to offer service to EQA providers and to the IVD industry for certifying control materials or calibrators.

Determinants of transfusion decisions in the ICU: haemoglobin concentration, what else? - a retrospective cohort study.

BACKGROUND AND OBJECTIVES: The aim of this study was to assess potentially relevant clinical characteristics which influence the decision to transfuse red cells in critically ill patients with low haemoglobin concentrations (6.0-10.0 g/dl). MATERIALS AND METHODS: This was a retrospective observational cohort study of patients admitted between November 2004 and May 2016 at the intensive care unit (ICU) of the Leiden University Medical Center, Netherlands. Haemoglobin measurements, clinical variables and the subsequent transfusion decision were extracted from the electronic health records. Clinical variables were grouped by organ system. We first examined the association of each of the clinical variables with the decision to transfuse during the following 6 h after a haemoglobin measurement using generalized estimating equations. We then compared the predictive abilities of single variables within an organ system and the predictive ability of an organ system's combined variables using the change in Akaike information criterion (AIC). RESULTS: A total of 83 394 haemoglobin measurements of 10 947 ICU admissions were included. Haemoglobin concentration was the most predictive for red cell transfusion. After the haemoglobin concentration, the combined variables for General Health, followed by the organ systems Cardiovascular and Pulmonary, were most predictive for red cell transfusion. Within these organ systems, the APACHE II score, referring department, APACHE admission diagnosis subgroup, troponin concentration, lactate concentration, respiratory rate, PaO2 /FiO2 and ventilation mode had the highest predictive ability. CONCLUSION: Haemoglobin concentration is the dominant predictor for red cell transfusion. Other clinical characteristics are also predictive, though to a lesser extent.

Systematic reviews and meta-analyses comparing mortality in restrictive and liberal haemoglobin thresholds for red cell transfusion: protocol for an overview of systematic reviews.

INTRODUCTION: There has been a significant increase in the number of systematic reviews and meta-analyses of randomised controlled trials investigating thresholds for red blood cell transfusion. To systematically collate, appraise and synthesise the results of these systematic reviews and meta-analyses, we will conduct an overview of systematic reviews. METHODS AND ANALYSIS: This is a protocol for an overview of systematic reviews. We will search five databases: MEDLINE, Embase, Web of Science Core Collection, PubMed (for prepublication, in process and non-Medline records) and Google Scholar. We will consider systematic reviews and meta-analyses of randomised controlled trials evaluating the effect of haemoglobin thresholds for red blood cell transfusion on mortality. Two authors will independently screen titles and abstracts retrieved in the literature search and select studies meeting the eligibility criteria for full-text review. We will extract data onto a predefined form designed to summarise the key characteristics of each review. We will assess the methodological quality of included reviews and the quality of evidence in included reviews. ETHICS AND DISSEMINATION: Formal ethics approval is not required for this overview as we will only analyse published literature. The findings of this study will be presented at relevant conferences and submitted for peer-review publication. The results are likely to be used by clinicians, policy makers and developers of clinical guidelines and will inform suggestions for future systematic reviews and randomised controlled trials. PROSPERO REGISTRATION NUMBER: CRD42019120503.

Determination of haemoglobin derivatives in aged dried blood spot to estimate haematocrit.

Introduction Dried blood spot (DBS) sample applications now encompass analytes related to clinical diagnosis, epidemiological studies, therapeutic drug monitoring, pharmacokinetic and toxicokinetic studies. Haematocrit (Hct) and haemoglobin (Hb) at very high or low concentrations may influence the accuracy of measurement quantification of the DBS sample. In this study, we aimed to predict the Hct of the punched DBS through primary spectrophotometric estimation of its haemoglobin-derivative (Hb-drv) content. Methods Formic acid solution was used to elute Hb-drv content of 3.2 mm spotted blood from its dry matrix. Direct spectrometry measurement was utilised to scan the extracted Hb-drv in the visible spectrum range of 520-600 nm. The linear relationship between an individual's Hct percentage and Hb-drv concentration was applied to estimate the Hct level of the blood spot. De-identified whole blood samples were used for the method development and evaluation studies. Results The Hb-drv estimation is valid in samples >2 months old. Method validation experiments DBS demonstrate linearity between 82.5 and 207.5 g/L, average coefficient of variation of 3.6% (intra-assay) and 7.7% (inter-assay), analytical recovery of 84%, and a high positive correlation (r=0.88) between Hb-drv and the original whole blood Hct. The Bland-Altman difference plot demonstrates a mean difference of 2.4% between the calculated DBS Hct and the directly measured Hct from fresh whole bloods. Conclusions We have successfully developed a simple Hb-drv method to estimate Hct in aged DBS samples. This method can be incorporated into DBS analytical work-flow for the in-situ estimation of Hct and subsequent correction of the analyte of interest as required.

A Restrictive Hemoglobin Transfusion Threshold of Less Than 7 g/dL Decreases Blood Utilization Without Compromising Outcomes in Patients With Hip Fractures.

INTRODUCTION: In patients with hip fracture, a transfusion threshold of hemoglobin (Hb) <8 g/dL is associated with similar or better outcomes than more liberal thresholds. Whether a more restrictive threshold of <7 g/dL Hb produces equivalent outcomes in such patients is unknown. The aim of the study was to examine whether a restrictive threshold of <7 g/dL Hb is safe in this population. METHODS: In January 2015, a blood management program was implemented that uses a restrictive transfusion threshold of <7 g/dL Hb in hemodynamically stable patients and <8 g/dL in patients with symptomatic anemia or a history of coronary artery disease. We identified 498 patients treated for hip fractures from January 2013 through May 2017. We compared perioperative outcomes of 207 patients treated before with those of 291 patients treated after restrictive threshold implementation. RESULTS: After restrictive threshold implementation, the proportion of patients receiving packed red blood cell (PRBC) transfusions decreased from 51% to 33% (P < 0.001); the mean number of PRBC units transfused per patient decreased by 40% (from 1.1 to 0.7; P < 0.001); inpatient cardiac morbidity decreased from 22.2% to 12.4% (P = 0.004); 30-day readmissions decreased from 14% to 8.6% (P = 0.04); and length of stay was unchanged (P = 0.06). Compared with the prerestrictive threshold cohort, the postrestrictive threshold group had lower odds of transfusion (odds ratio [OR] = 0.42; 95% confidence interval [CI], 0.29 to 0.62); transfusion of >1 unit of PRBCs (OR = 0.34; 95% CI, 0.22 to 0.52); and inpatient cardiac morbidity (OR = 0.45; 95% CI, 0.27 to 0.75). No significant differences were observed in inpatient morbidity, mortality, 30-day readmission, or 90-day survival. DISCUSSION: A restrictive threshold of <7 g/dL Hb in hemodynamically stable patients with hip fractures is associated with noninferior perioperative outcomes and less blood utilization compared with a threshold of <8 g/dL. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Hemoglobin Concentration in Children at Different Altitudes in Peru: Proposal for [Hb] Correction for Altitude to Diagnose Anemia and Polycythemia.

The present study was designed to define the hemoglobin [Hb] increase with altitude in Peruvian children. We suggest the normal range of [Hb] as means ±2 standard deviations (SD), with a value less than - 2 SD as a possible threshold to detect anemia. The prevalence of anemia was calculated. These values were compared to the World Health Organization (WHO) altitude correction parameter and the threshold for anemia of 11 g/dL. Likewise, polycythemia is suggested as [Hb] greater than 2 SD. 2,028,701 children aged 6-59 months were analyzed. The quadratic regression analysis shows that [Hb] is constant between sea level and 999 m. Thereafter, [Hb] increases from 11.32 g/dL (1000 m) up to ∼14.54 g/dL at 4000 m. Applying the threshold for anemia defined by WHO (11 g/dL) results in a prevalence of ∼35% for children living at altitudes <1000 m, and prevalence decreases to ∼4.5% at >4000 m. After [Hb] altitude correction, the prevalence was ∼36% (1000 m) and increases to ∼66% above 4000 m. With our proposed threshold for anemia, the prevalence was ∼15% below 1000 m and ∼5% above 4000 m. For polycythemia ([Hb] >14.5 g/dL), increases were from 1.2% at <1000 m to 39.4% at 4000 m. After [Hb] correction for altitude, the prevalence of polycythemia decreases with altitude. Excessive erythrocytosis defined as [Hb] >19 g/dL shows the highest values at 4000 m, while polycythemia defined as [Hb] greater than 2 SD was reduced at high altitude (HA). In conclusion, using WHO thresholds for anemia and [Hb] correction by altitude most likely overestimates the prevalence of anemia and may underestimate polycythemia in Peruvian children living at HA. Therefore, new threshold values for anemia and polycythemia as mean [Hb] less than 2 SD and greater than 2 SD for populations living at a specific altitude are suggested.

Applying newer parameter Ret-He (reticulocyte haemoglobin equivalent) to assess latent iron deficiency (LID) in blood donors-study at a tertiary care hospital in India.

BACKGROUND: It is important to detect Latent Iron Deficiency (LID) to prevent development of an overt iron deficiency anemia. Early detection is difficult by using conventional hematological and biochemical parameters. Soluble transferrin receptor (sTfR) is presently the gold standard for diagnosing LID. We evaluated the utility of Reticulocyte Hemoglobin Equivalent (Ret-He), a newer hematological parameter, to predict LID in blood donors as compared to sTfR. METHODS: This was a randomized prospective study performed on 501 donor samples over a period of three-months. All donors were included after administering medical history questionnaire and a brief physical examination in accordance with national guidelines (Hb ≥12.5). Additional samples were collected during donation according to the institutional standard operating procedure (SOP). All hemograms were performed on the Sysmex XE-2100 analyzer which included Ret-He. sTfR was measured in batch assays by ELISA (Biovendor, Czech Republic). Ret He <28 pg and sTfR≥3µg/ml were used to diagnose LID. Serum Iron, Total Iron Binding Capacity (TIBC) and Serum Ferritin were also measured simultaneously. RESULTS: Of the 501 blood donors, sTfR and Ret-He detected LID in 148 and 135 donors respectively. In comparison to sTfR, Ret-He had sensitivity of 92.7%, a specificity of 97.16%, PPV of 93.1% and NPV of 96.3%. Serum Ferritin, TIBC and serum Iron had comparatively lower sensitivity of 87.16%, 79.7% and 77.7% respectively. CONCLUSION: Ret-He can be used as a routine screening test to detect LID in blood donors. This could provide an opportunity to make appropriate and timely interventions like dietary changes or drug supplementation.

Reference intervals for reticulocyte hemoglobin content in healthy infants.

OBJECTIVES: Iron deficiency anemia in childhood is a serious public health problem worldwide. Reticulocyte hemoglobin content (Ret-He) is a novel biomarker of iron deficiency adopted for adults but there is a lack of reference intervals for Ret-He in infants. The aim of this study was to provide data from healthy infants. METHODS: Swedish infants (n = 456), born at term after normal pregnancies were included. Ret-He was measured at birth (umbilical cord sample), 48-72 h, 4 months, and 12 months. Reference intervals were calculated as ±2 standard deviations from the mean of Ret-He. RESULTS: Reference intervals for newborn Ret-He were 27.4 to 36.0 pg/L (N = 376) in the cord sample, 28.1-37.7 pg/L (N = 253) at 48-72 h, 25.6-33.4 pg/L (N = 341) at four months and 24.9-34.1 pg/L (N = 288) at 12 months. Ret-He was significantly lower among iron-deficient infants, at 4 months mean difference (95% CI) -4.2 pg/L (-6.1 to -2.4) and at 12 months mean difference (95% CI) -3.4 pg/L (-5.0 to -1.8). CONCLUSIONS: This longitudinal study presents Ret-He reference intervals based on non-anemic and non-iron-deficient infants and constitutes a step towards standardizing Ret-He as a pre-anemia biomarker of iron deficiency in children.

Internal quality assurance of HIL indices on Roche Cobas c702.

Automatic assessment of hemoglobin (H), lipaemia (L) and icterus (I) in serum or plasma (HIL indices) is the mainstay for evaluating sample quality. We planned this study to verify whether in-house prepared internal quality control (IQC) materials may be suitable for quality assurance of HIL indices. Pools containing different values of each of the three HIL indices were prepared from routine plasma samples, divided in aliquots and frozen at -20°C. Stability of frozen materials was assessed by thawing one aliquot of each pool after different days of freezing (1, 4, 8, 15, 22 and 29), and by measuring HIL indices on baseline fresh samples and frozen-thawed aliquots with Roche Cobas c702. Five fresh liquid IQCs materials were also measured at the same time points. Intra-assay and inter-assay imprecision of HIL indices calculated with commercial IQC materials ranged between 1.1-2.0% and 1.6-3.3%, respectively. When target values of HIL indices were calculated using frozen-thawed aliquots, the inter-assay imprecision of in-house prepared materials was optimal, even better than that of commercial liquid IQCs (H-index, 0.8% versus 1.6%; L-index, 2.2% versus 2.5%; I-index, 0.8% versus 3.3%). In conclusion, in-house prepared IQC materials are cost-effective alternatives to commercial liquid IQCs for HIL quality assurance.