Untangling the Complex Multidimensionality of the Social Determinants of Cardiovascular Health: A Systematic Review

Background: The cardiovascular literature is limited by the lack of consensus on what are the best metrics for reporting social determinants of health (SDH) or social deprivation, and if they should be reported as a single metric or separately by their domains. Methods: A systematic review of the literature on cardiovascular surgeries and procedures was conducted, identifying articles from January 1, 2010, to December 31, 2023, that studied the relationship between health outcomes after cardiovascular procedures or surgeries and SDH/social deprivation. The cardiovascular procedures/surgeries of interest were coronary and valve surgeries and procedures including coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), valve replacement or repair, and transcatheter aortic valve intervention. Results: After screening 638 articles, we identi ﬁ ed 47 papers that met our inclusion and exclusion criteria. The most common procedure evaluated was CABG and PCI; 46 of the studies focused on these 2 procedures. Almost all of the articles reported a different metric for SDH/social deprivation (41 different metrics); despite this, all of the metrics showed a consistent relationship with worse outcomes associated with greater degrees of SDH/deprivation. Only 9 reported on the individual domains of SDH/social deprivation; 3 studies showed a discordant relationship. Conclusions: Although our systematic review identi ﬁ ed numerous articles evaluating the relationship between SDH/social deprivation in cardiovascular disease, there was substantial heterogeneity in which metric was used and how it was reported. This reinforces the need for standards as


R ESUM E
Contexte : La litt erature m edicale sur les chirurgies cardiovasculaires est limit ee par l'absence de consensus sur les meilleures mesures à utiliser pour les d eterminants sociaux de la sant e ou du d enuement social et sur le moyen de les d eclarer : en une seule mesure ou s epar ement, selon le domaine.M ethodologie : Une revue syst ematique de la litt erature sur les chirurgies et proc edures cardiovasculaires a et e r ealis ee, et portait sur les articles publi es entre le 1 er  Social determinants of health (SDH) encompass the social and economic factors that influence individuals' and groups' health status. 1 Such factors include access to education, socioeconomic status, race, gender, and employment status. 1,2ocial deprivation refers to the level of exclusion an individual faces from common needs that support well-being. 3 Previous studies have established a consistent and strong relationship between worsening social environment and adverse health outcomes. 3That said, a major limitation in the literature is the way in which SDH or social deprivation is defined.Typically, SDH and social deprivation are constructs consisting of several domains.In some studies, these domains are collapsed into a single summary metric of "deprivation or SDH"; in other studies, they are reported separately.Compounding this wide variation in definition, when individual domains of SDH are actually reported, there is a lack of clarity on the interactions that may occur between the individual domains and their individual impacts on cardiovascular disease (CVD) outcomes.It is unclear if all domains are concordant in their relationships with outcomes and, if discordant, whether that should translate to reporting standards of each domain considered separately rather than a summary metric.Previous studies have yet to explore these questions.Accordingly, to address this gap in knowledge, we conducted a systematic review of the literature to answer the following research questions: 1.In the published literature on cardiovascular procedures and surgeries examining the relationship between SDH/ social deprivation and health outcomes, is SDH/social deprivation reported as a single metric or across separate domains?2. In the published literature on cardiovascular procedures and surgeries examining the relationship between SDH/ social deprivation and health outcomes, when reported, is the relationship between the domains of SDH/social deprivation and outcomes concordant or discordant?

Methods
We conducted and reported our systematic review consistent with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. 4Ovid Medline was searched from January 1, 2010, to December 31, 2023, to identify articles evaluating the relationship between health outcomes after cardiovascular procedures or surgeries and SDH or social deprivation.The cardiovascular procedures and surgeries of interest were coronary and valve surgeries and procedures including coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), valve replacement/ repair, and transcatheter aortic valve intervention (TAVI).We included primary articles only that specifically defined SDH or social deprivation as a covariable of interestdthis was captured using the specific search terms "social deprivation" and "social determinants of health."Exclusion criteria included animal studies, paediatric populations, and none The data elements that were extracted from each study were based on an a priori developed case report form.We extracted data on the type of cardiovascular procedure or surgery, the year of publication, the metric used for SDH or social deprivation, and if the metric was reported as a single summary score or if each dimension of SDH or social deprivation was reported separately.Finally, if the dimensions were reported separately, we determined if the relationship of each dimension with outcomes was concordant (similar).
We did not systematically assess for bias in the papers, because we anticipated that the majority would be retrospective in nature.A priori, our intent was to describe our results descriptively with no meta-analytic approaches to combine results from individual studies.

Results
Our search process is summarised in Figure 1.The initial search on Ovid Medline led to 638 articles being screened.We removed 27 duplicates, and during the title and abstract screen 363 review articles were excluded.The remaining 248 articles were screened based on their full text, and 47 met our inclusion criteria.
Characteristics of the 47 included studies are presented in Table 2, listed in reverse chronologic order.The most common procedure evaluated was CABG and PCId46 of the studies focused on these 2 procedures.We identified only 1 paper on TAVR and none that focused on surgical valve replacement or repair exclusively.We included 2 studies that studied postecardiac arrest patients and 10 that evaluated patients after acute coronary syndrome, because the vast majority of patients in those studies had undergone PCI or CABG during the index admission.
There was wide variation in how SDH or social deprivation was measured; indeed, almost every study used a different metric (41 metrics in 47 papers).Only 2 measures were found in multiple studies: The Social Deprivation Index (SDI) was used in 3 studies, and the Area Deprivation Index (ADI) was used in 5 studies.Despite this, even when a common metric was used, it was reported in a variety of ways.For example, the SDI was sometimes reported as quintiles, sometimes as tertiles; similarly, the ADI was reported as deciles in 1 study, and as quintiles in the other 4 studies that used that metric.
In most studies (38/47, 81%) SDH or social deprivation was described by a single summary value.Only 9 studies reported on the multiple domains.Of these, 3 reported a discordant relationship between the domains evaluated and their relationship with outcomes.In the other 6, a concordant relationship was observed.For example, in a TAVI study examining postprocedural outcomes, worsening neighbour residential instability was associated with worse outcomes after TAVI, and other dimensions (ethnicity and material deprivation) of social deprivation had no effect. 5In contrast, studies that focused only on the domains of education and income on average showed consistent results regarding the relationship between education and income to outcomes.

Discussion
In order to understand how SDH and social deprivation are defined and the potential complexities of these constructs, we evaluated the contemporary literature on the relationship between SDH and social deprivation on health outcomes after common cardiovascular surgeries and procedures.To our knowledge, this is the first systematic review in the literature addressing this specific knowledge gap.The majority of studies that we found reported on a single measure of SDH or social deprivation.Only 9 studies reported on individual domains of SDH or social deprivation, with roughly twothirds finding a concordant relationship and the other onethird finding a discordant relationship.
It has been generally accepted that socioeconomically disadvantaged patients have significantly worse outcomes following cardiac procedures and surgeries.Indeed, despite the many different metrics used to define SDH and social deprivation in the present study, this was broadly true.This is reassuring.
The novel insights (Fig. 2) that we provide are that there is a lack of consistency in how SDH or social deprivation is defined, which makes evaluation of this literature extremely difficult and comparisons between studies almost impossible.Moreover, this study suggests that using a single summary statistic to collapse the multiple dimensions of SDH and social deprivation may not be appropriate, as each dimension may have a unique relationship with the outcomes.This is particularly true if the constructs for SDH are comprehensive and include income and education as well as residential status, material deprivation, and ethnicity.Indeed, reporting of each domain's relationship with outcomes provided additional insights.
The present systematic review reinforces the need for more study in this area, and ideally for a consensus on which domains should make up SDH and social deprivation as well as standards on how they should be reported.In the absence of this, the literature will continue to be difficult to interpret.Reaching consensus on an ideal metric for social deprivation and how best to report this metric and its domains will entail an involved process such as a Delphi panel that would ideally include international participants from different jurisdictions.We would argue that such an effort is justified in light of the heterogeneity in the literature that we found.Such heterogeneity has potential policy implications, because unclear evidence from studies may be a barrier to interventions to address the disparities in health that marginalized persons suffer.
janvier 2010 et le 31 d ecembre 2023 qui abordaient la relation entre les issues de sant e après une intervention ou chirurgie cardiovasculaire et les d eterminants sociaux de la sant e ou le d enuement social.Les interventions et chirurgies cardiovasculaires d'int erêt comprenaient le pontage aortocoronarien, l'intervention coronarienne percutan ee (ICP), le remplacement ou la r eparation d'une valve et l'implantation valvulaire aortique par cath eter.R esultats : Après avoir pass e au crible 638 articles, nous avons recens e 47 articles qui r epondaient à nos critères d'inclusion et motifs d'exclusion.Les interventions les plus couramment evalu ees etaient le pontage aortocoronarien et l'ICP; 46 etudes se concentraient sur ces deux interventions.Presque tous les articles utilisaient une mesure diff erente des d eterminants sociaux de la sant e ou du d enuement social (41 paramètres diff erents); malgr e tout, toutes les mesures montraient une relation coh erente entre les issues n egatives et un plus haut degr e de d enuement social ou des d eterminants sociaux de la sant e d efavorables.Seules 9 etudes ont signal e les domaines individuels des mesures des d eterminants sociaux de la sant e ou du d enouement social; 3 ont montr e une relation conflictuelle.Conclusions : Même si notre revue syst ematique a permis de recenser de nombreux articles evaluant la relation entre les d eterminants sociaux de la sant e ou le d enuement social et la maladie cardiovasculaire, on a constat e une h et erog en eit e importante dans les paramètres utilis es et dans la d eclaration des mesures.Cette observation r eitère la n ecessit e de normaliser les mesures des d eterminants sociaux de la sant e ou du d enuement social et d' elaborer des pratiques exemplaires dans la d eclaration de ces mesures.

Table 1 .
Search strategy PCI or angioplasty or stent or CABG or coronary artery bypass grafting).mp[mp¼title, book title, abstract, original title, name of substance word, subject heading word, floating subheading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word] 208,7522(surgical aortic valve replacement or SAVR or TAVR or TAVI or transcatheter aortic valve implantation or transcatheter valve implantation).mp[mp ¼ title, book title, abstract, original title, name of substance word, subject heading word, floating subheading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms, population supplementary concept word, anatomy supplementary concept word] Figure 1.Flow diagram.

Table 2 .
Included studies

Table 2 .
Continued.Articles that met the search criteria were exported to Covidence, a review management tool, to be screened and further filtered.The basis for inclusion was determined through screening of titles, abstracts, and full-text review.Two investigators (N.V., A.Z.) independently screened all the exported studies and decided separately on inclusion.If there was disagreement on the suitability of an article, a third reviewer (H.C.W.) made the final decision on inclusion or exclusion.Table1presents the full search strategy.

Table 2 .
Continued.Ontario Marginalization Index; PCI, percutaneous coronary intervention; SES, socioeconomic status; SDI, Social Deprivation Index; TAVI, transcatheter aortic valve intervention; SVI, Social Vulnerability Index; SWEDEHEART, Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies.