Dataset Information

Insufficient iodine nutrition status and the risk of pre-eclampsia: a protocol for systematic review and meta-analysis.

ABSTRACT:

Introduction

Pre-eclampsia is one of the leading causes of maternal and perinatal morbidity and mortality worldwide. Although subclinical hypothyroidism (SCH) in pregnancy is one of the established risk factors for pre-eclampsia, the link between iodine deficiency, the main cause of hypothyroidism and pre-eclampsia remains uncertain. About two?billion people live in areas with iodine insufficiency. The increased renal blood flow during pregnancy leading to increased renal iodine clearance together with the increased placental transfer of iodine to the fetus leads to further iodine deficiency in pregnancy. Iodine is one of the most potent exogenous antioxidants whose deficiency is associated with oxidant imbalance and endothelial dysfunction, one of the mechanisms associated with increased risk of pre-eclampsia.

Methods and analysis

A systematic search of published literature will be conducted for case-control studies that directly determined the iodine nutrition status of women with pre-eclampsia and appropriate normotensive controls. A similar search will be conducted for cohort studies in which the incidence of pre-eclampsia among pregnant women with adequate and inadequate iodine nutrition status was reported. Databases including MEDLINE, EMBASE, Google Scholar, SCOPUS and Africa Wide Information will be searched up to 31 December 2018. Screening of identified articles and data extraction will be conducted independently by two investigators. Risk of bias of the included studies will be assessed using a Newcastle-Ottawa Scale. Appropriate meta-analytic techniques will be used to pool prevalence and incidence rates, odds and relative risk of pre-eclampsia from studies with similar features, overall and by geographical regions. Heterogeneity of the estimates across studies will be assessed and quantified and publication bias investigated. This protocol is reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis protocols (PRISMA-P) 2015 guidelines.

Ethics and dissemination

Since the proposed study will use published data, there is no requirement for ethical approval. This review seeks to identify the risk of pre-eclampsia associated with insufficient iodine nutrition in pregnancy. This will help to ascertain whether insufficient iodine intake may be an independent risk factor for pre-eclampsia. This will advise policy makers on the possibility of maximising iodine nutrition in pregnancy and reproductive age as one of the remedies for prevention of pre-eclampsia among populations at risk of inadequate iodine intake. This review is part of the thesis that will be submitted for the award of a PhD in Medicine to the Faculty of Health Sciences of the University of Cape Town. In addition the results will be published in a peer-reviewed journal.

Prospero registration number

CRD42018099427.

SUBMITTER: Businge CB

PROVIDER: S-EPMC6538048 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Publications

Insufficient iodine nutrition status and the risk of pre-eclampsia: a protocol for systematic review and meta-analysis.

Businge Charles Bitamazire CB Madini Namhla N Longo-Mbenza Benjamin B Kengne A P AP

BMJ open 20190524 5

<h4>Introduction</h4>Pre-eclampsia is one of the leading causes of maternal and perinatal morbidity and mortality worldwide. Although subclinical hypothyroidism (SCH) in pregnancy is one of the established risk factors for pre-eclampsia, the link between iodine deficiency, the main cause of hypothyroidism and pre-eclampsia remains uncertain. About two billion people live in areas with iodine insufficiency. The increased renal blood flow during pregnancy leading to increased renal iodine clearanc ...[more]

PMID: 31129578

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Project description:BACKGROUND:Insufficient iodine intake in pregnancy is associated with many adverse pregnancy outcomes. About 90% of African countries are at risk of iodine deficiency due to poor soils and dietary goitrogens. Pregnancy predisposes to insufficient iodine nutrition secondary to increased physiological demand and increased renal loss. Iodine deficiency is re-emerging in countries thought to be replete with pregnant women being the most affected. This review seeks to identify the degree of iodine nutrition in pregnancy on the entire African continent before and after the implementation of national iodization programmes. METHODS:A systematic search of published literature will be conducted for observational studies that directly determined the prevalence of insufficient iodine intake among pregnant women in Africa. Electronic databases and grey literature will be searched for baseline data before the implementation of population-based iodine supplementation and for follow-up data up to December 2018. Screening of identified articles and data extraction will be conducted independently by two investigators. Risk of bias and methodological quality of the included studies will be assessed using a risk of bias tool. Appropriate meta-analytic techniques will be used to pool prevalence estimates from studies with similar features, overall and by major characteristics including the region of the study, time period (before and after implementation of iodization programmes), sample size and age. Heterogeneity of the estimates across studies will be quantified and publication bias investigated. This protocol is reported according to Preferred Reporting Items for Systematic reviews and Meta-Analysis protocols (PRISMA-P) 2015 guidelines. DISCUSSION:This review will help ascertain the impact of national iodization programmes on the iodine nutrition status in pregnancy in Africa and advise policy on the necessity for monitoring and mitigating iodine deficiency in pregnancy in Africa. This review is part of a thesis that will be submitted to the Faculty of Health Sciences, University of Cape Town, for the award of a PhD in Medicine whose protocol has been granted ethics approval (UCT HREC 135/2018). In addition, the results will be published in a peer-reviewed journal. SYSTEMATIC REVIEW REGISTRATION:PROSPERO CRD42018099434.

Project description:IntroductionPre-eclampsia is an important cause of death and complication for pregnant women and perinatal infant. Low-dose aspirin has been most commonly used to prevent pre-eclampsia in high-risk pregnant women. Recently, heparins have also been used alone or in combination with aspirin to prevent pre-eclampsia. However, the optimal doses and combination therapy of aspirin and heparins are not well established. Therefore, we aim to compare aspirin, heparins and their combination to prevent pre-eclampsia in a network meta-analysis.Methods and analysisWe will search the following electronic databases from the date of database establishment to 8 January 2019: PubMed, Embase, Cochrane Library, Web of Science and ProQuest. We will also search additional studies manually. There will be no restriction on the language of publications. Only randomised clinical trials will be eligible in our network meta-analysis. We will include pregnant women who have been recommended for aspirin according to the standard of the American Congress of Obstetricians and Gynecologists, or were designated as high risk in some recent studies. We will include studies comparing the effects of any single or combination of aspirin and heparins with placebo or observation or another intervention in pregnancy. We will include studies that reported one of the following outcomes: pre-eclampsia, severe pre-eclampsia, preterm delivery, perinatal death and full-term pre-eclampsia with delivery at ≥37 weeks. Traditional pairwise meta-analysis will be performed initially, and then network meta-analysis will be performed using frequency analysis method. Subgroup analyses and sensitivity analyses will be conducted to assess the robustness of the findings.Ethics and disseminationThis network meta-analysis does not require ethical certification. An overview and information on the prevention of pre-eclampsia in high-risk pregnant women will be provided by this network meta-analysis.Prospero registration numberCRD42018084248.

Project description:Evidence accumulates for associations between hypertensive pregnancy disorders and increased cardiovascular risk later. The main goal of this study was to explore shared biomarkers representing common pathogenic pathways between heart failure with preserved ejection fraction (HFpEF) and pre-eclampsia where these biomarkers might be potentially eligible for cardiovascular risk stratification in women after hypertensive pregnancy disorders. We sought for blood markers in women with diastolic dysfunction in a first literature search, and through a second search, we investigated whether these same biochemical markers were present in pre-eclampsia.This systematic review and meta-analysis presents two subsequent systematic searches in PubMed and EMBASE. Search I yielded 3014 studies on biomarkers discriminating women with HFpEF from female controls, of which 13 studies on 11 biochemical markers were included. Cases had HFpEF, and controls had no heart failure. The second search was for studies discriminating women with pre-eclampsia from women with non-hypertensive pregnancies with at least one of the biomarkers found in Search I. Search II yielded 1869 studies, of which 51 studies on seven biomarkers were included in meta-analyses and 79 studies on 12 biomarkers in systematic review.Eleven biological markers differentiated women with diastolic dysfunction from controls, of which the following 10 markers differentiated women with pre-eclampsia from controls as well: C-reactive protein, HDL, insulin, fatty acid-binding protein 4, brain natriuretic peptide, N terminal pro brain natriuretic peptide, adrenomedullin, mid-region pro adrenomedullin, cardiac troponin I, and cancer antigen 125.Our study supports the hypothesis that HFpEF in women shares a common pathogenic background with pre-eclampsia. The biomarkers representing inflammatory state, disturbances in myocardial function/structure, and unfavourable lipid metabolism may possibly be eligible for future prognostic tools.

Project description:INTRODUCTION:Compared to women with normotensive pregnancies, women with a history of pre-eclampsia have a roughly fourfold increased risk of developing chronic arterial hypertension and a twofold increased risk of developing cardiovascular disease (CVD). Lifestyle changes, such as increased physical activity, weight loss, smoking cessation and healthy diet, are effective for CVD prevention in the general population. However, no scoping review or systematic review of postpartum lifestyle interventions among women with pre-eclampsia have, to our best knowledge, been performed. The objective of this scoping review is to provide an overview of the available research literature on postpartum lifestyle interventions to reduce the risk of CVD among women with pre-eclampsia. METHODS AND ANALYSIS:The protocol is based on the framework outlined by Arksey and O'Malley. Databases to be searched include: PubMed, Embase CINAHL and the JBI Database of Systematic Reviews and Implementation Reports. The search will be performed after the publication of this protocol (estimated to be 1 June 2020) and will be repeated 1 month prior to the submission for publication of the final review (estimated to be 1 January 2021). The review will consider studies that include women in the postpartum period (in particular, but not restricted to, the first 12 months after delivery), with a history of pre-eclampsia. Data will be extracted by two independent reviewers using a data extraction tool including specific details about the population, concept, context, study methods and key findings relevant to the review objective. Any disagreements between the reviewers will be resolved through discussion, or with a third reviewer. The extracted data will be presented in diagrammatic or tabular form that align with the objective of this scoping review. A narrative summary will accompany the tabulated and/or charted results and will describe how the results relate to the reviews objective and questions. ETHICS AND DISSEMINATION:Since all data will be obtained from publicly available materials, the proposed scoping review does not require ethical approval. The results will be submitted for publication in an open-access peer-reviewed journal and presented at relevant conferences.

Project description:BackgroundThe risk of myocardial infarction (MI) increases during pregnancy, particularly in women with pre-eclampsia. MI is diagnosed by measuring high blood levels of cardiac-specific troponin (cTn), although this may be elevated in women with pre-eclampsia without MI, which increases diagnostic uncertainty. It is unclear how much cTn is elevated in uncomplicated and complicated pregnancy, which may affect whether the existing reference intervals can be used in pregnant women. Previous reviews have not investigated high-sensitivity troponin in pregnancy, compared to older, less sensitive methods.MethodsElectronic searches using the terms "troponin I" or "troponin T", and "pregnancy", "pregnancy complications" or "obstetrics". cTn levels were extracted from studies of women with uncomplicated pregnancies or pre-eclampsia.ResultsThe search identified ten studies with 1581 women. Eight studies used contemporary methods that may be too insensitive to use reliably in this clinical setting. Two studies used high-sensitivity assays, with one reporting an elevation in troponin I (TnI) in pre-eclampsia compared to uncomplicated pregnancy, and the other only examining women with pre-eclampsia. Seven studies compared cTn between women with pre-eclampsia or uncomplicated pregnancy using any assay. Seven studies showed elevated TnI in pre-eclampsia compared to uncomplicated pregnancy or non-pregnant women. One study measured troponin T (TnT) in pregnancy but did not examine pre-eclampsia.ConclusionTnI appears to be elevated in pre-eclampsia, irrespective of methodology, which may reflect the role of cardiac stress in this condition. TnI may be similar in healthy pregnant and non-pregnant women, but we found no literature reporting pregnancy-specific reference intervals using high-sensitivity tests. This limits broader application of cTn in pregnancy. There is a need to define reference intervals for cTn in pregnant women, which should involve serial sampling throughout pregnancy, with careful consideration for gestational age and body mass index, which cause dynamic changes in normal maternal physiology.

Dataset Information

Insufficient iodine nutrition status and the risk of pre-eclampsia: a protocol for systematic review and meta-analysis.

Introduction

Methods and analysis

Ethics and dissemination

Prospero registration number

Publications

Insufficient iodine nutrition status and the risk of pre-eclampsia: a protocol for systematic review and meta-analysis.

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