CommentRevisiting WHO haemoglobin thresholds to define anaemia in clinical medicine and public health
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Cited by (58)
Relationship between anemia and its correlates and cognitive function in Chinese patients with chronic schizophrenia: A large cross-sectional study
2024, Schizophrenia Research: CognitionAlthough both anemia and schizophrenia (SCZ) can cause cognitive decline, it is unclear whether anemia worsens cognitive decline in patients with SCZ. The primary objective of this study was to investigate the prevalence of anemia and the relationship between anemia, SCZ symptom severity, and cognitive function in patients with SCZ.
We obtained demographic and clinical data from 1690 inpatients with SCZ. All psychiatric symptoms and cognitive functioning were assessed by the Positive and Negative Syndrome Scale (PANSS), the Mini-Mental State Examination (MMSE), and the Repeated Battery for the Assessment of Neuropsychological Status (RBANS). Hemoglobin (HGB) values as well as red blood cell (RBC) counts were collected by routine blood tests.
The proportion of anemia in patients with SCZ was 26.36 % (383/1453). Compared to SCZ patients without anemia, SCZ patients with anemia were older, had a lower bodyweight, a smaller waist circumference and lower apolipoprotein B levels, but longer QT intervals. Further logistic regression analysis revealed that anemia was associated with age, gender, and weight. In addition, there was no difference in cognitive function between SCZ patients with and without anemia.
Our findings suggest a high proportion of anemia in patients with chronic SCZ in the Han Chinese population. Several demographic and clinical variables are associated with anemia in SCZ patients.
Haemoglobin thresholds to define anaemia from age 6 months to 65 years: estimates from international data sources
2024, The Lancet HaematologyDetection of anaemia is crucial for clinical medicine and public health. Current WHO anaemia definitions are based on statistical thresholds (fifth centiles) set more than 50 years ago. We sought to establish evidence for the statistical haemoglobin thresholds for anaemia that can be applied globally and inform WHO and clinical guidelines.
In this analysis we identified international data sources from populations in the USA, England, Australia, China, the Netherlands, Canada, Ecuador, and Bangladesh with sufficient clinical and laboratory information collected between 1998 and 2020 to obtain a healthy reference sample. Individuals with clinical or biochemical evidence of a condition that could reduce haemoglobin concentrations were excluded. We estimated haemoglobin thresholds (ie, 5th centiles) for children aged 6–23 months, 24–59 months, 5–11 years, and 12–17 years, and adults aged 18–65 years (including during pregnancy) for individual datasets and pooled across data sources. We also collated findings from three large-scale genetic studies to summarise genetic variants affecting haemoglobin concentrations in different ancestral populations.
We identified eight data sources comprising 18 individual datasets that were eligible for inclusion in the analysis. In pooled analyses, the haemoglobin fifth centile was 104·4 g/L (90% CI 103·5–105·3) in 924 children aged 6–23 months, 110·2 g/L (109·5–110·9) in 1874 children aged 24–59 months, and 114·4 g/L (113·6–115·2) in 1839 children aged 5–11 years. Values diverged by sex in adolescents and adults. In pooled analyses, the fifth centile was 122·2 g/L (90% CI 121·3–123·1) in 1741 female adolescents aged 12–17 years and 128·2 g/L (126·4–130·0) in 1103 male adolescents aged 12–17 years. In pooled analyses of adults aged 18–65 years, the fifth centile was 119·7 g/L (90% CI 119·1–120·3) in 3640 non-pregnant females and 134·9 g/L (134·2–135·6) in 2377 males. Fifth centiles in pregnancy were 110·3 g/L (90% CI 109·5–111·0) in the first trimester (n=772) and 105·9 g/L (104·0–107·7) in the second trimester (n=111), with insufficient data for analysis in the third trimester. There were insufficient data for adults older than 65 years. We did not identify ancestry-specific high prevalence of non-clinically relevant genetic variants that influence haemoglobin concentrations.
Our results enable global harmonisation of clinical and public health haemoglobin thresholds for diagnosis of anaemia. Haemoglobin thresholds are similar between sexes until adolescence, after which males have higher thresholds than females. We did not find any evidence that thresholds should differ between people of differering ancestries.
World Health Organization and the Bill & Melinda Gates Foundation.
Anemia in Pregnancy With CKD
2024, Kidney International ReportsChronic kidney disease (CKD), anemia, and iron deficiency are global health issues affecting individuals in both high-income and low-income countries. In pregnancy, both CKD and iron deficiency anemia increase the risk of adverse maternal and neonatal outcomes, including increased maternal morbidity and mortality, stillbirth, perinatal death, preterm birth, and low birthweight. However, it is unknown to which extent iron deficiency anemia contributes to adverse outcomes in CKD pregnancy. Furthermore, little is known regarding the prevalence, pathophysiology, and treatment of iron deficiency and anemia in pregnant women with CKD. Therefore, there are many unanswered questions regarding optimal management with oral or i.v. iron and recombinant human erythropoietin (rhEPO) in these women. In this review, we present a short overview of the (patho)physiology of anemia in healthy pregnancy and in people living with CKD. We present an evaluation of the literature on iron deficiency, anemia, and nutritional deficits in pregnant women with CKD; and we evaluate current knowledge gaps. Finally, we propose research priorities regarding anemia in pregnant women with CKD.
Prevalence, years lived with disability, and trends in anaemia burden by severity and cause, 1990–2021: findings from the Global Burden of Disease Study 2021
2023, The Lancet HaematologyAnaemia is a major health problem worldwide. Global estimates of anaemia burden are crucial for developing appropriate interventions to meet current international targets for disease mitigation. We describe the prevalence, years lived with disability, and trends of anaemia and its underlying causes in 204 countries and territories.
We estimated population-level distributions of haemoglobin concentration by age and sex for each location from 1990 to 2021. We then calculated anaemia burden by severity and associated years lived with disability (YLDs). With data on prevalence of the causes of anaemia and associated cause-specific shifts in haemoglobin concentrations, we modelled the proportion of anaemia attributed to 37 underlying causes for all locations, years, and demographics in the Global Burden of Disease Study 2021.
In 2021, the global prevalence of anaemia across all ages was 24·3% (95% uncertainty interval [UI] 23·9–24·7), corresponding to 1·92 billion (1·89–1·95) prevalent cases, compared with a prevalence of 28·2% (27·8–28·5) and 1·50 billion (1·48–1·52) prevalent cases in 1990. Large variations were observed in anaemia burden by age, sex, and geography, with children younger than 5 years, women, and countries in sub-Saharan Africa and south Asia being particularly affected. Anaemia caused 52·0 million (35·1–75·1) YLDs in 2021, and the YLD rate due to anaemia declined with increasing Socio-demographic Index. The most common causes of anaemia YLDs in 2021 were dietary iron deficiency (cause-specific anaemia YLD rate per 100 000 population: 422·4 [95% UI 286·1–612·9]), haemoglobinopathies and haemolytic anaemias (89·0 [58·2–123·7]), and other neglected tropical diseases (36·3 [24·4–52·8]), collectively accounting for 84·7% (84·1–85·2) of anaemia YLDs.
Anaemia remains a substantial global health challenge, with persistent disparities according to age, sex, and geography. Estimates of cause-specific anaemia burden can be used to design locally relevant health interventions aimed at improving anaemia management and prevention.
Bill & Melinda Gates Foundation.
Association between maternal haemoglobin concentrations and maternal and neonatal outcomes: the prospective, observational, multinational, INTERBIO-21st fetal study
2023, The Lancet HaematologyAnaemia in pregnancy is a global health problem with associated maternal and neonatal morbidity and mortality. We aimed to investigate the association between maternal haemoglobin concentrations during pregnancy and the risk of adverse maternal and neonatal outcomes.
In this prospective, observational, multinational, INTERBIO-21st fetal study conducted at maternity units in Brazil, Kenya, Pakistan, South Africa, and the UK, we enrolled pregnant women (aged ≥18 years, BMI <35 kg/m2, natural conception, and singleton pregnancy) who initiated antenatal care before 14 weeks' gestation. At each 5±1 weekly visit until delivery, information was collected about the pregnancy, as well as the results of blood tests taken as part of routine antenatal care, including haemoglobin values. The outcome measures were maternal (gestational diabetes, pregnancy-induced hypertension, and preterm premature rupture of membranes) and neonatal outcomes (small for gestational age, preterm birth, and acute respiratory distress syndrome).
Between Feb 8, 2012, and Nov 30, 2019, 2069 women (mean age 30·7 years [SD 5·0]) had at least one routinely haemoglobin concentration measured at 14–40 weeks' gestation, contributing 4690 haemoglobin measurements for the analysis. Compared with a haemoglobin cutoff of 110 g/L, the risk was increased more than two-fold for pregnancy-induced hypertension at haemoglobin concentrations of 170 g/L (risk ratio [RR] 2·29 [95% CI 1·19–4·39]) and higher, for preterm birth at haemoglobin concentrations of 70 g/L (RR 2·04 [95% CI 1·20–3·48]) and 165 g/L (RR 2·06 [95% CI 1·41–3·02]), and for acute respiratory distress syndrome at haemoglobin concentrations of 165 g/L (RR 2·84 [95% CI 1·51–5·35]). Trimester-specific results are also presented.
Our data suggests that the current WHO haemoglobin cutoffs are associated with reduced risk of adverse maternal and neonatal outcomes. The current haemoglobin concentration cutoffs during pregnancy should not only consider thresholds for low haemoglobin concentrations that are associated with adverse outcomes but also define a threshold for high haemoglobin concentrations given the U-shaped relationship between haemoglobin concentration and adverse neonatal and maternal outcomes.
Bill & Melinda Gates Foundation.
Hemoglobin distributions and prevalence of anemia in a multiethnic United States pregnant population
2023, American Journal of Clinical NutritionFew normative longitudinal hemoglobin data are available to estimate the prevalence and risk factors for anemia among a multiethnic United States pregnant population.
The aim of this study was to characterize hemoglobin distributions and prevalence of anemia in a pregnant population receiving care at a large urban medical center.
A retrospective medical chart review was undertaken in 41,226 uncomplicated pregnancies of 30,603 pregnant individuals who received prenatal care between 2011 and 2020. Mean hemoglobin concentrations and anemia prevalence in each trimester and incidence of anemia during pregnancy in a subset of 4821 women with data in each trimester were evaluated in relation to self-reported race and ethnicity and other possible risk factors. Risk ratios (RRs) of anemia were determined using generalized linear mixed-effects models. Smoothed curves describing changes in hemoglobin across pregnancy were created using generalized additive models.
The overall prevalence of anemia was 26.7%. The observed fifth percentiles of the hemoglobin distributions were significantly lower than the United States CDC anemia cutoffs in the second and third trimesters (T3). The RR (95% CI) of anemia were 3.23 (3.03, 3.45), 6.18 (5.09, 7.52), and 2.59 (2.48, 2.70) times higher in Black women than that in White women in each trimester, respectively. Asian women recorded the lowest risk of anemia compared with other racial groups in T3 (compared with White womenRR: 0.84; 95% CI: 0.74, 0.96). Hispanic women presented a higher risk of anemia in T3 than non-Hispanic women (RR: 1.36; 95% CI: 1.28, 1.45). In addition, adolescents, individuals with higher parity, and those carrying multiple fetuses experienced a higher risk of developing anemia in late gestation.
Anemia was evident in more than one-quarter of a multiethnic United States pregnant population despite current universal prenatal iron supplementation recommendations. Prevalence of anemia was higher among Black women and lowest among Asian and White women.