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School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, CanadaDivision of Cardiac Prevention and Rehabilitation, University of Ottawa Heart Institute, Ottawa, Ontario, CanadaBrain and Heart Nexus Research Program, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
Division of Cardiac Prevention and Rehabilitation, University of Ottawa Heart Institute, Ottawa, Ontario, CanadaDivision of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, CanadaCanadian Women’s Heart Health Centre, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, CanadaBrain and Heart Nexus Research Program, University of Ottawa Heart Institute, Ottawa, Ontario, CanadaIC/ES, Ottawa, Ontario, Canada
Women with a history of hyperBtensive disorders of pregnancy (HDP) are at particularly high risk for cardiovascular disease (CVD) and CVD-related death, and certain racial and ethnic subpopulations are disproportionately affected by these conditions. We examined the use of race, ethnicity, and national origin in observational studies assessing CVD morbidity and mortality in women with a history of HDP. A total of 124 studies, published between 1976 and 2021, were reviewed. We found that white women were heavily overrepresented, encompassing 53% of all participants with HDP. There was limited and heterogeneous reporting of race and ethnicity information across studies and only 27 studies reported including race and/or ethnicity variables in at least 1 statistical analysis. Only 2 studies mentioned the use of these variables as a strength; several others (k = 18) reported a lack of diversity among participants as a study limitation. Just over half of included articles (k = 68) reported at least 1 sociodemographic variable other than race and ethnicity (eg, marital status and income); however, none investigated how they might have worked synergistically or antagonistically with race and/or ethnicity to influence participants’ risk of CVD. These findings highlight significant areas for improvement in cardiovascular obstetrics research, including the need for more robust and standardized methods for collecting, reporting, and using sociodemographic information. Future studies of CVD risk in women with a history of HDP should explicitly examine racial and ethnic differences and use an intersectional approach.
Les femmes ayant des antécédents de troubles hypertensifs de la grossesse (THG) présentent un risque particulièrement élevé de maladies cardiovasculaires (MCV) et de décès liés à ces dernières, et certaines sous-populations raciales et ethniques sont touchées de manière disproportionnée par ces maladies. Nous avons examiné l’utilisation de la race, de l’ethnicité et de l’origine nationale dans les études observationnelles évaluant la morbidité et la mortalité liées aux MCV chez les femmes ayant des antécédents de THG. Un total de 124 études, publiées entre 1976 et 2021, ont été examinées. Nous avons constaté que les femmes blanches étaient fortement surreprésentées, puisqu’elles constituaient 53 % de l’ensemble des participantes atteintes de THG. Les renseignements relatifs à la race et à l’ethnicité étaient limités et hétérogènes d’une étude à l’autre, et seules 27 études ont indiqué avoir tenu compte de variables relatives à la race ou à l’ethnicité dans au moins une analyse statistique. Seules deux études ont mentionné l’utilisation de ces variables comme un point fort; plusieurs autres (k = 18) ont signalé un manque de diversité parmi les participantes comme une limite de l’étude. Un peu plus de la moitié des articles inclus (k = 68) ont fait état d’au moins une variable sociodémographique autre que la race et l’ethnicité (p. ex., l’état matrimonial et le revenu); aucun toutefois n’a étudié la manière dont ces variables auraient pu agir en synergie ou en opposition avec la race ou l’ethnicité pour influencer le risque de MCV des participantes. Ces résultats mettent en évidence des points importants à améliorer dans la recherche sur l’obstétrique cardiovasculaire, notamment la nécessité de méthodes plus fiables et normalisées en matière de collecte, de communication et d’utilisation des données sociodémographiques. Les prochaines études sur le risque de MCV chez les femmes ayant des antécédents de THG devraient examiner explicitement les différences raciales et ethniques et adopter une approche intersectionnelle.
Cardiovascular disease (CVD) is the leading cause of hospitalization among Canadian women,
Substantial heterogeneity exists in the association between HDP and CVD, such that certain racial and ethnic subpopulations (eg, non-Hispanic black and American Indian or Alaska Native women) are disproportionately affected by these conditions.
the concepts of race and ethnicity are complex and often not assessed or reported precisely enough for research needs. This is especially problematic for authors of systematic reviews (SRs) and meta-analyses, which can provide the highest level of evidence for causal association,
Because the use of race and/or ethnicity can affect the quantification of cardiovascular risk estimates, it is imperative that researchers (1) carefully report on and discuss why race and ethnicity variables are used, (2) discuss how these variables are assessed, and (3) discuss the potential implications of study findings based on their use.
note the need to avoid erroneously attributing disparities in health outcomes to specific racial or ethnic groups without attempting to understand or investigate the underlying causes of disparities. To this end, a 2020 report
published by the Canadian Institute for Health Information outlined proposed standards for collecting race and indigenous identity data in health care, noting a lack of consensus on data collection standards for these variables. Further, as recently as March 2021, Ontario-based administrative health data provider ICES
announced a call for participants to become members of a “People’s Panel” with the goal of creating of a race and ethnicity data framework “to ensure the anti-racist use of race, ethnicity and immigration data.”
Medical journals are also taking note of the need for more careful consideration of the terminology used when describing race and ethnicity. For example, a 2021 Journal of the American Medical Association
editorial discussed revisions to its submission requirements on race and ethnicity and announced a formal request for input on ways to improve.
Given recent and increasing calls for improved reporting and analysis of race and ethnicity, coupled with the serious short and long-term consequences that HDP can have on women’s cardiovascular health and its increasing global prevalence
—it is prudent to examine how researchers have used race and ethnicity in studies assessing CVD risk in women with a history of HDP. To address this gap, in this rapid review, we conducted a new analysis examining the use of race, ethnicity, and national origin in prior observational studies assessing CVD morbidity and mortality in women with a history of HDP.
A rapid review is a type of evidence synthesis produced using streamlined systematic review (SR) methodology to address a predefined research question(s) and the most rigorous methods that a reduced timeframe allows.
there is no standardized approach to conduct a rapid review, as the methods used should be tailored to meet the specific needs of the study (eg, the expertise of the research team, nature of the evidence base, research question[s], and study aims) as well as those of the end user.
that explored the use of race and ethnicity in epidemiologic and health services research. We build on this literature by focusing our exploration of these concepts within the context of studies estimating cardiovascular risk in women with a history of HDP.
We used recently published SRs/meta-analyses to populate an initial list of potentially eligible primary studies. Full descriptions of eligibility criteria for both SRs and primary studies are provided in Supplemental Tables S1 and S2, respectively. Briefly, SRs were eligible for inclusion if authors included observational studies (ie, cohort studies, case-control studies, and cross-sectional studies) examining CV morbidity and mortality in women with a history of HDP. Specific CVDs of interest included heart failure, arrhythmias, ischemic heart disease (including coronary heart disease and myocardial infarction), stroke, and death from CV causes. In addition to these CV outcomes, SRs that included studies examining the association between HDP and chronic hypertension (HTN) were also of interest because of its robust association with CVD risk and mortality.
2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines.
Included primary studies obtained from published SRs and the literature search update (see Literature Search and Screening section) were screened for inclusion according to the inclusion criteria shown in Supplemental Table S2. Conference abstracts, letters, case reports, opinion pieces, and studies published in languages other than English were excluded. No restrictions were placed on year of publication for primary studies.
Literature search and screening
Two literature searches were designed and carried out by an experienced research librarian (S.V.) on May 20, 2021, in MEDLINE (see Supplemental Tables S3 and S4 for full search details). The first search was carried out to identify recently published SRs. The second literature search was used to identify recently published primary studies. Both searches comprised terms related to pregnancy-induced hypertensive disorders and were informed by previously conducted systematic literature searches.
published from 2019 to present. A gray literature search was not undertaken. All results were exported to Covidence (Melbourne, Australia), and duplicates were eliminated using the platform’s duplicate identification feature.
Deduplicated search results were imported into DistillerSR (Ottawa, Canada), which was used to facilitate the screening and data extraction process for our race and ethnicity analysis. SRs and primary studies were managed in separate project folders. First, the titles/abstracts of all records identified through literature searches were screened for inclusion by a single author (A.J.) against the eligibility criteria. The full text of all records identified as potentially eligible based on the results of the title/abstract screen were then assessed for full eligibility. The included study lists of fully eligible SRs were then imported into EndNote (New York, NY) bibliographic software and the platform’s duplicate identification feature was used to remove duplicate records. All deduplicated records were then imported into DistillerSR and the full texts screened for inclusion.
Extraction of race and ethnicity data from primary studies
All data were independently extracted by three authors (A.J., V.T., S.D.) into customized extraction forms housed in DistillerSR. Pilot tests were completed on 5 studies by all reviewers, and adjustments were made as required before full data extraction began. Two reviewers (A.J., S.D.) audited extracted data for completeness and accuracy. When necessary, disagreements were resolved by consensus.
Data extracted from fully eligible primary studies included:
Study characteristics (author name, publication year, journal name and type, funding, country of conduct, cardiovascular outcomes reported, study design, data source, aims and objectives)
Race, ethnicity, and geographical origin of participants (geographical origin or participants; if and where race and ethnicity were reported in the study; the terms used to describe race and ethnicity; how race and ethnicity were defined, assessed, and reported; whether and how race and ethnicity were included in analyses; and number of participants by race or ethnic category by HDP diagnosis)
Other sociodemographic characteristics reported by authors (eg, participant income, marital status, education, employment, religious affiliation)
Study and population characteristics were only extracted if they were relevant to this review. For example, information about irrelevant exposures and comparison groups such as gestational diabetes or women with a history of normotensive pregnancies was not extracted. Further, in the event of a composite exposure (eg, maternal placental syndrome), only information about participants with HDP was extracted. If the geographic location of participants was not stated, the location of the corresponding author was extracted in its place. Supplemental material and previously published methods were not routinely collected or examined for information of interest unless authors explicitly reported that information pertinent to this review was reported elsewhere (eg, supplemental analyses by race or ethnicity or demographic information presented for the study population). Studies were considered to have included participants of a single race or ethnicity if authors made explicit statements such as “black women.”
In accordance with our rapid review protocol, included primary studies were not formally assessed for quality. However, given that we were interested in the reporting and use of race, ethnicity, and national origin in studies of observational design, we noted which studies made use of the Strengthening of Reporting of Observational Studies in Epidemiology (STROBE)
Because the STROBE guidelines were published in 2007, we only looked for the use of these guidelines in primary studies published in 2008 or later.
All included SRs from which most our primary studies were obtained were independently assessed for quality by 2 independent reviewers (V.T., S.D.) using A Measurement Tool to Assess Systematic Reviews” (AMSTAR-2).
Discrepancies were adjudicated by a third reviewer (A.J.).
We use the term women when reporting all results, as this is the term that was used in all included studies to describe study participants. We recognize that this is a gendered term that may not be generalizable to all study participants and acknowledge that not all currently or previously pregnant persons identify as women.
Study selection and general characteristics
After screening 196 records identified through literature search one, we identified a total of 6 SRs, published in 2020
(Supplemental Table S5; Figure S1) from which an initial set of 174 potentially eligible primary studies were identified. A total of 524 records were obtained from our second search for recently published primary studies. After excluding records that did not meet our eligibility criteria, a total of 124 primary studies
All included primary studies were published between 1976 and 2021, with most studies (72%) published in the last 10 years. Across included studies, we noted a general lack of reporting on the theoretical justification for using (or omitting) race and/or ethnicity in statistical models as well as a lack of justification for, or reflection on, the methods used to classify participants into a particular race and/or ethnicity group. Of the 103 studies published in 2008 or later, only 2
included a copy of their checklist summarizing where each item was addressed in their manuscript.
Most studies used a cohort design (k = 98; 79.0%), 12 were case-control studies (9.7%), and 14 were of cross-sectional design (11.3%). A wide range of HDP diagnoses were reported in included studies, with more than half of participants (or HDP deliveries) having been diagnosed with PE alone or one of 15 author-reported PE subtypes. The authors of about a quarter of included studies (k = 35) reported that HDP diagnoses were obtained using International Classification of Diseases (ICD) codes, and in 19 studies, this information was obtained from participant questionnaires (ie, self-reported obstetric history) (Supplemental Table S7).
Just over half of included studies (k = 64) reported on the risk or odds of HTN in women with a history of HDP. In 45 of those studies, HTN was the only reported outcome of interest. The second most commonly reported cardiovascular outcome was ischemic heart disease (including coronary heart disease and myocardial infarction), which was reported by 30% of included studies. A similar but slightly lower proportion of studies reported on stroke (27%; k = 34) and a further 24 studies reported on CVD as a composite outcome. An additional 23 studies also reported on cardiovascular mortality. Finally, 13% of included studies reported on heart failure, whereas only 4% (k = 5) reported on risk of cardiac arrhythmia in women with a history of HDP.
Geographic location of participants
Figure 1 shows a geographic heat map of the global spread of participants represented in cardiovascular obstetrics (cardio-obstetrics) research as it pertains to women with a history of HDP. Three quarters of participants with a history of HDP (including HDP deliveries) resided in the United States (n = 3,382,939). Of the remaining 1,093,303 participants, most (81%) were from the United Kingdom (n = 363,830; 33.3%), Denmark (n = 193,331; 17.7%), Norway (n = 174,243; 15.9%), and Canada (n = 156,082; 14.3%). The least well represented countries included Turkey (n = 25), India (n = 39), Kenya (n = 63), Chile (n = 71) and Brazil (n = 70). Only one study
women. Across the other 106 studies, a modest percentage reported any race- and ethnicity-related information (eg, as related to participant characteristics or in their introduction or discussion sections of their article). As summarized in Figure 2, since the 1970s, the average proportion of studies reporting on these sociodemographic constructs has generally increased over time from 33% of articles published from 1978 to 2001 to 67% of articles published in 2018 to 2021 (103% change).
Of the 106 studies that did not explicitly involve participants of the same race or ethnic group, only 65 authors reported information pertaining to race or ethnicity anywhere in their published manuscript. Nearly 68% (k = 44) reported on participant race and/or ethnic group in a results table (eg, participant characteristics), and only 30 (46%) also discussed participant race and/or ethnicity in the results text (Table 1). Only 2 studies
mentioned the use of race and/or ethnicity variables as a strength of their study; however, several more (k = 18) reported that a lack of racial and/or ethnic diversity among study participants was a study limitation. One study completed in Canada
Among studies that included race and/or ethnicity in at least 1 inferential analysis (apart from descriptive analyses) (k = 27). Note that some studies may have used more than 1 term; thus, the total is more than 27.
Among studies that included race and/or ethnicity in at least 1 inferential analysis (apart from descriptive analyses) (k = 27). Note that some studies may have used more than 1 term; thus, the total is more than 27.
Reported significant findings
Called for further research
∗ Among studies that reported on race and/or ethnicity of participants and did not involve 1 race or ethnic group exclusively (k = 65).
§ Among studies that included race and/or ethnicity in at least 1 inferential analysis (apart from descriptive analyses) (k = 27). Note that some studies may have used more than 1 term; thus, the total is more than 27.
Nearly one-third of included studies reported that participant race and/or ethnicity was assessed through participant self-report (eg, through questionnaires), whereas just over one quarter (k = 17) were assigned to a racial and/or ethnic category based on the use of existing records (eg, clinical registries). Twenty-nine percent of studies (k = 19) referred to race and/or ethnicity as demographic variables, whereas only 5
reported excluding participants of other race/ethnicity from analysis because of low numbers. More than half of these studies (approximately 52%) reported significant findings related to race and/or ethnicity, but only 10 discussed them in detail. Five studies
, called for further research to address knowledge gaps related to the generalizability of findings to more diverse populations.
Reporting of participant race and ethnicity
As shown in Table 2, 61 studies (49%) did not report on participant race and/or ethnicity. Among those that did (k = 45), the highest number of race and/or ethnic groups reported in a single study was 7, which was noted in 2 studies published in 2018
The range of race and ethnicity groups reported on by studies was extensive, with the highest proportion of studies reporting participants of white race (Table 3). Several studies (k = 22) reported that participant race or ethnicity was unknown, missing, unspecified, or other, and several different terms were used to describe the same construct (eg, Caucasian, white, non-Hispanic white, European descent). Only 3 studies
A total of 2,871,907 women with a history of any HDP (or HDP deliveries) were categorized into a race or ethnic group by study authors. More than 1.5 million participants (53%) were described as white, Caucasian, non-Hispanic white, or European (including Finnish, Norweigan, and Dutch)—2.8 times more participants than the next highest represented race or ethnic group, Hispanic or Latino (n = 544,957) (Figure 3). Nearly 110,000 participants with a history of HDP were classified as other, unknown or unspecified race or ethnicity, representing 4% of the total. Just over 400 participants were described as African and 35 women with HDP in included studies were Iranian.
Other sociodemographic variables
Although the primary focus of this review was on the reporting of race and/or ethnicity, we also noted other sociodemographic variables reported on by authors of included studies (see Supplemental Table S6). Briefly, just over half of included studies (k = 68) reported on at least 1 sociodemographic variable other than race and ethnicity, such as participant marital status, socioeconomic status, religious affiliation, and type of health insurance. Of these, most authors (74%) also explicitly reported having included 1 or more of those factors as an adjustment variable or covariate in at least 1 statistical model. These types of sociodemographic varibles varied widely across studies, both in terms of how they were defined, breadth of variables reported, and in terms of the combination of variables that were incorporated into statistical models.
The most commonly reported sociodemographic variables reported by authors were participant education and marital status. Measures of socioeconomic status and social class varied most widely, ranging from factors such as annual family income,
). These scores combined information about a variety of factors such as car ownership, neighbourhood-level social class and overcrowding, and highest level of education and occupation, among other factors.
used husband’s occupation as a measure of participant social class but provided no rationale for doing so (eg, participants may not have been employed outside the home, and the tools used to assess social class did not account for this kind of work).
Only 25 (20%) studies reported on participant sociodemographic information in addition to race and/or ethnicitiy; however, none investigated how the additional sociodemographic variables they collected (eg, education, marital status, income, rural vs urban setting, insurance payer) may have had synergistic or antagonistic effects with race and/or ethnicity to influence participants’ risk of CVD.
In this review, we examined the use of race, ethnicity, and national origin in observational studies assessing CVD morbidity and mortality in women with a history of HDP. Overall, we found limited and heterogeneous reporting of race and ethnicity information across included studies. Despite evidence of substantial racial and ethnic differences in the prevalence estimates for HDP, which range from less than 3% for Chinese and Vietnamese women to 8.9% for Indigenous American women and nearly 10% for non-Hispanic black women,
were also poorly represented. Despite the burden of HDP being higher across several racial and ethnic minority groups, almost no studies examined race and/or ethnicity differences in the association between HDP and CVD outcomes.
Findings in light of previous research
The methodologic issues related to the reporting and use of race and/or ethnicity identified in this review align with those reported in several published studies.
we found limited reporting of race and ethnicity information across included studies, and, when authors did report this information, several different terms were used to describe the same construct (eg, Caucasian, white, non-Hispanic white, European descent). Further, we identified only 1 study
noted that a substantive portion of studies in general medicine, surgery, and oncology published between 2007 and 2018 reported non convenience race or ethnic groupings. Similarly, we found that across included studies, thousands of women with HDP were assigned to a category referred to as other to represent their race. In addition, we noted that only 3 studies
included in this review reported any category that captured individuals who identify as multiracial. This finding is concerning given that individuals who identifiy as multiracial may experience inequalities in health that are different from those who identify with a single racial group.
all of which were published in 2016 or later, still reported individuals as belonging to a combined Asian/Pacific Islander race. This finding points to the limitations of using registry and administrative data in epidemiologic studies, as researchers using these types of data cannot control how they are collected and may not be able to adapt their reporting of variables if data collection methods change over time.