The change in haemoglobin concentration between the first and third trimesters of pregnancy: a population study

© 2019 The Authors. Published by BMC. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1186/s12884-019-2495-0Background: The physiological fall in haemoglobin concentration from the 1st to the 3rd trimester of pregnancy is often quoted as 5 g/L. However, other studies have suggested varying levels of fall between 8 and 13 g/L. We evaluated the change in haemoglobin concentration between the 1st and 3rd trimesters of pregnancy in a multi-ethnic population of pregnant women. Methods: A retrospective cohort analysis of 7054 women with singleton pregnancies, giving birth during 2013-15 in a single urban maternity unit in England. We calculated the changes in haemoglobin concentration from 1st to 3rd trimester using the first trimester haemoglobin as the reference point. The population was stratified into sub-groups to explore any differences that existed within the population. Results: In general the fall in haemoglobin concentration was in the order of 14 g/L or 11% of the first trimester value. This fall was consistent for the majority of sub-groups of the population. The fall was lower (7.7%) in the most deprived section of the population, IMD1, but it increased to 11.7% when we restricted that sub-group to pregnant women without health problems during the index pregnancy. Conversely, there was an increase in haemoglobin of 10.2% in women whose first trimester haemoglobin concentration was in the lowest 5% of the total study population. The population fall in haemoglobin was 10.2 g/L (7.8%), after excluding cases above the 95th and below the 5th centiles, and women with a medical and/or obstetric disorder during the pregnancy. Conclusion: The fall in haemoglobin during pregnancy is in the order of 14 g/L or 11% of the first trimester level. This is 2 to 3 times higher than suggested by some guidelines and higher than previously published work. The results challenge the current accepted thresholds for practice, and have broader implications for diagnosis and managment of antenatal anaemia. Tweetable abstract: Fall in haemoglobin across pregnancy is around 14 g/L (11%) and significantly higher than previously stated in the pregnant population. This poses questions over currently accepted thresholds for anaemia in pregnancy.Marian Knight is funded by a National Institute for Health Research (NIHR) Research Professorship. The funding sources had no role in the study, and the researchers were independent from the funders. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Published versio

Pathways of association between maternal haemoglobin and stillbirth: Path-analysis of maternity data from two hospitals in England

© 2018 The Authors. Published by BMJ Publishing Group. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: http://dx.doi.org/10.1136/bmjopen-2017-020149© 2018 Article author(s) (or their employer(s) unless otherwise stated in the text of the article). Objective To investigate the mechanisms that link maternal haemoglobin concentration with stillbirth. Design A retrospective cohort analysis using anonymised maternity data from two hospitals in England. Setting The Royal Wolverhampton NHS Trust and Guy's and St Thomas' NHS Foundation Trust. Study population 12 636 women with singleton pregnancies ≥24 weeks of gestation giving birth in the two hospitals during 2013-2015. Method A conceptual framework of hypothesised pathways through birth weight-for-gestational age and maternal infection including potential confounders and other risk factors was developed and examined using path-analysis. Path-analysis was performed by fitting a set of regression equations using weighted least squares adjusted for mean and variance. Goodness-of-fit indices were estimated. Main outcome measures Coefficient of association (β) for relationship between each parameter, and direct, indirect and total effects via the postulated pathways. Results The path-model showed a significant adjusted indirect negative effect of maternal haemoglobin on stillbirth mediated via birth weight-for-gestational age (standardised estimate (SE)=-0.01; 95% CI=-0.01 to-0.001; P=0.028). The effect through maternal infection was not significant at P<0.05 (SE=0.001; 95% CI=-0.004 to 0.01; P=0.610). There was a residual direct negative effect of maternal haemoglobin on stillbirth (SE=-0.12; 95% CI-0.23 to-0.02; P=0.020) after accounting for the two pathways. Total indirect SE=-0.004; 95% CI-0.01 to 0.003; P=0.267; total direct and indirect SE=-0.13; 95% CI-0.23 to-0.02; P=0.016. The goodness-of-fit indices showed a good fit between the model and the data. Conclusion While some of the influence on risk of stillbirth acts through low birth weight-for-gestational age, the majority does not. Several new mechanisms have been suggested for how haemoglobin may be exerting its influence on the risk of stillbirth possibly involving genetic, epigenetic and/or alternative obstetric and nutritional pathologies, but much more research is needed.MK is funded by a National Institute for Health Research (NIHR) Research Professorship (NIHR-RP-011-032).Published versio

Iron supplementation to treat anaemia in adult critical care patients: a systematic review and meta-analysis

Anaemia affects 60-80 % of patients admitted to intensive care units (ICUs). Allogeneic red blood cell (RBC) transfusions remain the mainstay of treatment for anaemia but are associated with risks and are costly. Our objective was to assess the efficacy and safety of iron supplementation by any route, in anaemic patients in adult ICUs.Electronic databases (CENTRAL, MEDLINE, EMBASE) were searched through March 2016 for randomized controlled trials (RCT)s comparing iron by any route with placebo/no iron. Primary outcomes were red blood cell transfusions and mean haemoglobin concentration. Secondary outcomes included mortality, infection, ICU and hospital length of stay, mean difference (MD) in iron biomarkers, health-related quality of life and adverse events.Five RCTs recruiting 665 patients met the inclusion criteria; intravenous iron was tested in four of the RCTs. There was no difference in allogeneic RBC transfusion requirements (relative risk 0.87, 95 % confidence interval (CI) 0.70 to 1.07, p = 0.18, five trials) or mean number of RBC units transfused (MD -0.45, 95 % CI -1.34 to 0.43, p = 0.32, two trials) in patients receiving or not receiving iron. Similarly, there was no difference between groups in haemoglobin at short-term (up to 10 days) (MD -0.25, 95 % CI -0.79 to 0.28, p = 0.35, three trials) or mid-term follow up (last measured time point in hospital or end of trial) (MD 0.21, 95 % CI -0.13 to 0.55, p = 0.23, three trials). There was no difference in secondary outcomes of mortality, in-hospital infection, or length of stay. Risk of bias was generally low although three trials had high risk of attrition bias; only one trial had low risk of bias across all domains.Iron supplementation does not reduce RBC transfusion requirements in critically ill adults, but there is considerable heterogeneity between trials in study design, nature of interventions, and outcomes. Well-designed trials are needed to investigate the optimal iron dosing regimens and strategies to identify which patients are most likely to benefit from iron, together with patient-focused outcomes.PROSPERO International prospective register of systematic reviews CRD42015016627 . Registered 2 March 2015

Coagulation status of critically ill patients with and without liver disease assessed using a novel thrombin generation analyzer

Funding Information: NHS Blood and TransplantPeer reviewedPublisher PD

Intravenous Iron to Treat Anaemia following Critical care (INTACT): A protocol for a feasibility randomised controlled trial

Background: Anaemia is common in patients who survive critical illness and is associated with high levels of fatigue and poor quality of life. In non-critically ill patients, treating anaemia with intravenous iron has resulted in meaningful improvements in quality of life, but uncertainties regarding the benefits, risks, timing and optimal route of iron therapy in survivors of critical illness remain.Methods / Design: INtravenous Iron to Treat Anaemia following CriTical care (INTACT) is an open-label, feasibility, parallel group, randomised controlled trial with 1:1 randomisation to either intravenous iron (1000 mg ferric carboxymaltose) or usual medical care. The primary objective is to assess the feasibility of a future, multicentre randomised controlled trial. Participants will be followed up for up to 90 days post-randomisation. The primary outcome measures, which will be used to determine feasibility, are recruitment and randomisation rates, protocol adherence and completeness of follow-up. Secondary outcome measures include collecting clinical, laboratory, health-related quality of life and safety data to inform the power calculations of a future definitive trial.Conclusion: Improving recovery from critical illness is a recognised research priority. Whether or not correcting anaemia, with intravenous iron, improves health-related quality of life and recovery requires further investigation. If so, it has the potential to become a rapidly translatable intervention. Prior to embarking on a phase III multicentre trial, a carefully designed and implemented feasibility trial is essential

Combining fractional polynomial model building with multiple imputation.

Multivariable fractional polynomial (MFP) models are commonly used in medical research. The datasets in which MFP models are applied often contain covariates with missing values. To handle the missing values, we describe methods for combining multiple imputation with MFP modelling, considering in turn three issues: first, how to impute so that the imputation model does not favour certain fractional polynomial (FP) models over others; second, how to estimate the FP exponents in multiply imputed data; and third, how to choose between models of differing complexity. Two imputation methods are outlined for different settings. For model selection, methods based on Wald-type statistics and weighted likelihood-ratio tests are proposed and evaluated in simulation studies. The Wald-based method is very slightly better at estimating FP exponents. Type I error rates are very similar for both methods, although slightly less well controlled than analysis of complete records; however, there is potential for substantial gains in power over the analysis of complete records. We illustrate the two methods in a dataset from five trauma registries for which a prognostic model has previously been published, contrasting the selected models with that obtained by analysing the complete records only

Performance of the PEdiatric Logistic Organ Dysfunction-2 score in critically ill children requiring plasma transfusions

BACKGROUND: Organ dysfunction scores, based on physiological parameters, have been created to describe organ failure. In a general pediatric intensive care unit (PICU) population, the PEdiatric Logistic Organ Dysfunction-2 score (PELOD-2) score had both a good discrimination and calibration, allowing to describe the clinical outcome of critically ill children throughout their stay. This score is increasingly used in clinical trials in specific subpopulation. Our objective was to assess the performance of the PELOD-2 score in a subpopulation of critically ill children requiring plasma transfusions. METHODS: This was an ancillary study of a prospective observational study on plasma transfusions over a 6-week period, in 101 PICUs in 21 countries. All critically ill children who received at least one plasma transfusion during the observation period were included. PELOD-2 scores were measured on days 1, 2, 5, 8, and 12 after plasma transfusion. Performance of the score was assessed by the determination of the discrimination (area under the ROC curve: AUC) and the calibration (Hosmer-Lemeshow test). RESULTS: Four hundred and forty-three patients were enrolled in the study (median age and weight: 1 year and 9.1 kg, respectively). Observed mortality rate was 26.9 % (119/443). For PELOD-2 on day 1, the AUC was 0.76 (95 % CI 0.71-0.81) and the Hosmer-Lemeshow test was p = 0.76. The serial evaluation of the changes in the daily PELOD-2 scores from day 1 demonstrated a significant association with death, adjusted for the PELOD-2 score on day 1. CONCLUSIONS: In a subpopulation of critically ill children requiring plasma transfusion, the PELOD-2 score has a lower but acceptable discrimination than in an entire population. This score should therefore be used cautiously in this specific subpopulation