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Health care delivery, economics and global health care
Systematic review
Environmental impact of cardiovascular healthcare
  1. Alexandra L Barratt1,2,
  2. Yan Li1,
  3. Isabelle Gooroovadoo1,
  4. Allyson Todd1,
  5. Yuanlong Dou1,
  6. Scott McAlister1,2,3 and
  7. Christopher Semsarian1,2,4,5
  1. 1Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
  2. 2Wiser Healthcare, The University of Sydney, Sydney, New South Wales, Australia
  3. 3Department of Critical Care, The University of Melbourne, Melbourne, Victoria, Australia
  4. 4Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Sydney, New South Wales, Australia
  5. 5Department of Cardiology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
  1. Correspondence to Professor Christopher Semsarian; c.semsarian{at}centenary.org.au

Abstract

Importance The healthcare sector is essential to human health and well-being, yet its significant carbon footprint contributes to climate change-related threats to health.

Objective To review systematically published studies on environmental impacts, including carbon dioxide equivalent (CO2e) emissions, of contemporary cardiovascular healthcare of all types, from prevention through to treatment.

Evidence review We followed the methods of systematic review and synthesis. We conducted searches in Medline, EMBASE and Scopus for primary studies and systematic reviews measuring environmental impacts of any type of cardiovascular healthcare published in 2011 and onwards. Studies were screened, selected and data were extracted by two independent reviewers. Studies were too heterogeneous for pooling in meta-analysis and were narratively synthesised with insights derived from content analysis.

Findings A total of 12 studies estimating environmental impacts, including carbon emissions (8 studies), of cardiac imaging, pacemaker monitoring, pharmaceutical prescribing and in-hospital care including cardiac surgery were found. Of these, three studies used the gold-standard method of Life Cycle Assessment. One of these found the environmental impact of echocardiography was 1%–20% that of cardiac MR (CMR) imaging and Single Photon Emission Tomography (SPECT) scanning. Many opportunities to reduce environmental impacts were identified: carbon emissions can be reduced by choosing echocardiography as the first cardiac test before considering CT or CMR, remote monitoring of pacemaker devices and teleconsultations when clinically appropriate to do so. Several interventions may be effective for reducing waste, including rinsing bypass circuitry after cardiac surgery. Cobenefits included reduced costs, health benefits such as cell salvage blood available for perfusion, and social benefits such as reduced time away from work for patients and carers. Content analysis revealed concern about the environmental impact of cardiovascular healthcare, particularly carbon emissions and a desire for change.

Conclusions and relevance Cardiac imaging, pharmaceutical prescribing and in-hospital care including cardiac surgery have significant environmental impacts, including CO2e emissions which contribute to climate-related threats to human health. Importantly, many opportunities to effectively reduce environmental impacts exist within cardiac care, and can provide economic, health and social cobenefits.

  • delivery of health care
  • systematic reviews as topic
  • health care economics and organizations

Data availability statement

No data are available.

http://creativecommons.org/licenses/by-nc/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi.org/10.1136/openhrt-2023-002279

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    WHAT IS ALREADY KNOWN ON THIS TOPIC

    • What are the environmental impacts of cardiovascular healthcare?

    WHAT THIS STUDY ADDS

    • Environmental impacts of cardiovascular healthcare include carbon emissions of cardiac imaging, pacemaker monitoring, prescribing and in-hospital care including cardiac surgery. Many opportunities to reduce environmental impacts were identified, and may provide health, financial and social cobenefits.

    HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

    • Cardiovascular healthcare improves health and prolongs life but also has environmental impacts, including carbon dioxide equivalent emissions which contribute to climate-related threats to human health, which warrant further attention.

    Introduction

    The healthcare sector is essential to human health and well-being, yet has a significant environmental footprint. If global healthcare was a country, it would be the fifth largest emitter of carbon dioxide equivalent (CO2e) emissions on the planet.1 Global healthcare is each year responsible for over two gigatons (2×109 tons) or 4%–5% of global greenhouse gas emissions, measured as CO2e emissions.2 In turn, these emissions contribute to climate change, and its health-related impacts, with annual emissions resulting in an estimated loss of 3 million disability-adjusted life-years (DALYs).3 At the UN Climate Conference (Glasgow COP26) in 2021, 50 countries committed to low carbon health systems, with 14 setting net-zero targets,4 reflecting increasing recognition of the need for healthcare to mitigate its emissions. Of note, environmental impacts may take many forms, beyond greenhouse gases emissions, from plastic and water pollution to small particulates that contribute to air pollution.5 As such, the environmental impacts of healthcare may undermine the primary mission of practitioners, and minimising them is essential.

    Cardiovascular diseases (CVDs), including coronary heart disease and stroke, are the most common non-communicable diseases worldwide. According to the Global Burden of Disease study, CVDs were responsible for >17 million deaths globally in 2017, and for >300 million years of life lost.6 Furthermore, the burden of CVD is increasing; 21% increase in deaths and 14% increase in years of life lost between 2007 and 2017 worldwide,6 and its control will continue to require considerable global healthcare resources. In this study, we aimed to review systematically published studies on the environmental impact of contemporary cardiovascular healthcare of all types, from prevention through to treatment.

    Methods

    Data sources and search strategy

    We searched Medline, Embase and Scopus for studies published from 2011. The search was initially conducted in September 2021, and rerun and updated on 31 March 2022 to identify any newly published articles. We searched broadly with a range of terms covering our key concepts of environmental impact assessment and cardiovascular healthcare. Based on trial searches, we developed our final search strategy: environmental.mp AND impact.mp AND cardi*.mp limited to publication date 2011 onwards and published in English. Forward and backward citation searching was undertaken for all included studies. (Further information on our search strategies is available in online supplemental file).

    Inclusion criteria

    We included systematic reviews and primary studies that measured and reported any type of environmental impact occurring as a result of testing, diagnosing, monitoring or treating CVDs in humans. Care could be delivered as primary care or in-hospital care, and we interpreted care to include any activity that cardiologists, cardiac surgeons or primary care physicians managing cardiovascular conditions might undertake. We excluded opinion pieces, review articles, protocols, conference proceedings (not published in a peer-reviewed journal), animal studies, studies of the impact of environmental change on human health, studies on the environmental impact of general medical practice, which were not specific to cardiovascular healthcare, dietary intervention studies and studies not published in English.

    Citation screening and study selection

    Titles and abstracts were screened for inclusion/exclusion independently by two reviewers, with disagreements resolved through discussion and consensus. All potentially relevant articles were retrieved for full-text review. Two reviewers independently considered full-text reports for inclusion and again disagreements were resolved by discussion and consensus. Citation management and study selection was undertaken using Covidence.

    Data extraction and presentation of findings

    Two reviewers extracted data independently from included studies with disagreements resolved by discussion and consensus, and data were verified by a third reviewer. For each study, details of publication, study characteristics, methods and findings were summarised in tables. Because of the diversity of the study types, research questions, methods used and outcomes reported, no quantitative synthesis was undertaken. In addition, two reviewers independently conducted content analysis to provide greater insight, again with any disagreements resolved by discussion and consensus. Content analysis identified key themes, how results were contextualised and cobenefits.

    Assessment of study quality

    Measuring the environmental impact of healthcare products is an emerging research field, drawing on the methods of environmental science and engineering, and the sustainability literature including waste and consumption audits. Environmental impacts of products are best quantified by life cycle assessment (LCA), an internationally standardised method (ISO 14040-44).7 LCA measures a diverse range of environmental emissions and their impacts, including water, land and air pollution and carbon emissions over the full life cycle of a defined product, from raw material acquisition through manufacturing, packaging, distribution, use and disposal (see figure 1). Downstream consequences of these impacts on human health can be estimated and reported as DALYs.

    Figure 1
    Figure 1

    Complete life cycle of a product from raw material acquisition to disposal.22

    Results

    Study characteristics and methods

    Of 1568 studies screened, 12 studies (10 papers and 2 abstracts) were included.8–19 A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram showing results of citation searching, screening and study selection process is provided (online supplemental figure 1). Forward and backward citation searching identified no additional studies.

    Table 1 reports characteristics of included studies. A wide range of types of cardiovascular healthcare were examined, including cardiac imaging, monitoring devices, drug treatments, diabetes management and in-hospital care for cardiac surgery. Teleconsultation and a cardiology conference were also studied. Diverse methodologies were used: LCA (n=3), eco-audit, consumption and/or waste studies (n=4), patient surveys (n=2), water contamination studies (n=2) and an economic modelling study (n=1).

    View this table:
    Table 1

    Characteristics of included studies

    In most studies (8/12), the main outcome was carbon emissions (reported in kg or tons/tonnes of CO2e emissions) (8/12 studies). Three of these studies used LCA to quantify CO2e emissions and reported additional environmental impacts including pollution, resource usage and estimates of long-term impacts on human health in DALYs. The five studies which did not use LCA estimated carbon emissions from consumption of electricity, healthcare services and products, financial costs, or reported distances travelled. The remaining four studies reported environmental outcomes as product usage or waste (two studies) or drug concentrations in waterways (two studies).

    Ten studies were descriptive only, that is, they measured or estimated the environmental impact of one or more cardiovascular healthcare products or services. While the authors may have used the results to make recommendations about practice changes to reduce environmental impacts, they did not test an intervention, such as a behavioural or educational intervention, to bring about practice change. In contrast, two studies tested such an intervention—these were a quality improvement intervention to reduce unnecessary test ordering, and a Lean Care intervention to reduce unnecessary use of personal protective equipment (PPE).

    Study findings

    The main findings of the 12 studies are shown in table 2 and summarised in figure 2. Echocardiography was found to have environmental impacts on human health, ecosystems and resource usage which were 1%–20% of those of cardiac MR (CMR) imaging or Single Photon Emission Tomography (SPECT), based on LCA.8 Stretchable cardiac monitoring devices were lower in carbon emissions (58% of those of rigid devices), and in other environmental impacts (22%–68% of those of rigid devices), again based on LCA results.9

    Figure 2
    Figure 2

    Summary of main findings—environmental impacts of cardiovascular healthcare: red circles cardiac care, blue circles general activities, green circle key environmental impacts. CO2e, carbon dioxide equivalent emissions.

    View this table:
    Table 2

    Study findings

    Remote monitoring of pacemakers10 and telephone consultations11 reduced estimated carbon emissions and costs, based on patient-reported travel data, compared with in-clinic appointments. The economic modelling study12 demonstrated that carbon emissions savings, both in absolute terms, and per Life Year gained, are predicted from effective diabetes management compared with cohorts with untreated or poorly controlled diabetes.

    Two studies examined concentrations of cardiovascular and lipid regulating drugs in effluent water released from municipal wastewater treatment plants, and in surface waters globally. Many cardiovascular drugs (58 of 82 drugs assessed in a systematic review of 322 studies,13 and 19 of 26 drugs assessed in a recent primary study in Shanghai, China)14 were detected in both types of waterways, in concentrations of up to several μg/L in wastewater and up to hundreds of ng/L in surface waters. ß-blockers, lipid regulating agents, ACE inhibitors, angiotension II receptor antagonists and diuretics were commonly studied and found in waterways, even after wastewater treatment. Physiological and reproductive effects on aquatic organisms (including shellfish and fish) were found, mostly for ß-blockers and lipid regulating drugs, including at concentrations found in some surface waters. Research is lacking currently on any possible impacts on human health from consumption.

    One study conducted an eco-audit of consumption of disposable medical products, pharmaceuticals (including anaesthetic gases) and electricity during cardiac surgery, and estimated that each adult cardiac surgery resulted in 124 kgCO2e emissions.18 Another study in the context of cardiac surgery examined whether the negative environmental impact of medically regulated waste treatment and disposal could be reduced by rinsing the by-pass circuits after use, thereby converting this waste from regulated medical waste to solid municipal waste.17 The rinsing procedure took no additional theatre time, cost less than US$2 per procedure for additional prime fluid, and diverted 15 lb of circuits from regulated medical waste per procedure. A cobenefit was 240 mL of cell salvage blood available for transfusion.

    Two studies evaluated interventions to reduce unnecessary or low value clinical care in before-and-after studies. In one study,15 the intervention was a quality improvement project consisting of staff engagement, educational posters and feedback on test ordering frequency, aimed at reducing unnecessary ordering of biochemical tests. The intervention in the other study16 used staff engagement and value stream mapping to increase the value of ward admission procedures, with the aim of reducing unnecessary use of PPE and minimising risk of staff exposure to COVID-19-positive patients. Both studies reported reductions in test ordering/PPE use, respectively, with associated reductions in costs, waste and estimated carbon emissions.

    The final LCA study19 looked at the environmental impact of holding a cardiology conference virtually by webinar (necessitated by the COVID-19 pandemic), compared with a hypothetical traditional conference of 2.5 days duration for 1374 attendees. The environmental impact of the virtual conference was 4 tons of CO2e emissions, compared with 1920 (note publication by Duane et al19 contains a typographical error reporting 192 tons) tons of CO2e emissions (1.4 tons of CO2e emissions per person) for the in-person conference, an estimated reduction of >99%.

    Findings from the content analysis

    We identified three key themes: (1) concern about cardiovascular healthcare’s environmental footprint and a desire to reduce it; (2) results being contextualised and (3) cobenefits. These themes and illustrative quotations from several studies are shown in table 3.

    View this table:
    Table 3

    Results of content analysis

    All studies’ stated research aims reflected awareness of the need to measure the environmental impact of cardiovascular healthcare, within the context of healthcare becoming more sustainable. Across all studies, authors were keen to move beyond measurement to propose or, in two studies to test, specific practice changes to reduce the environmental impact of cardiovascular healthcare. They used various ways to make their study results more meaningful to readers. The most commonly reported cobenefits of reducing environmental impacts were cost savings, health benefits, such as salvage blood for transfusion, and reduced risk of exposure to COVID-19-positive patients, and social benefits such as reduced time away from work and reduced burden on carers’ time.

    Discussion

    This is the first study to review evidence on the environmental footprint of cardiovascular healthcare. Activities undertaken regularly in the course of delivering cardiac care, including imaging, testing, monitoring, prescribing and surgical intervention, all have environmental impacts, including carbon emissions which contribute to climate change. Importantly, many opportunities exist to effectively reduce environmental impacts within cardiac care, and can provide economic, health and social cobenefits.

    Motivation appears high among investigators to find ways to reduce impact, and these studies have highlighted a variety of ways this could be done. Some options include using echocardiography as the first-line test, before considering CMR imaging or SPECT, using stretchable rather than rigid devices, using remote pacemaker monitoring when clinically appropriate to do so, and reducing or avoiding low value care. CVD drugs are widespread in waterways and highlight the need to avoid unnecessary prescribing but also the importance of effective management in primary care, for example, of type 2 diabetes which can reduce environmental impact by effective prevention of disease progression.

    Implementation of simple, low-cost interventions, such as quality improvement programmes, aimed at cutting unnecessary test ordering and use of PPE, can realise environmental benefits and reduce costs. Changes to theatre practice, to reduce waste and rinse bypass circuits, can have environmental benefits, reduce costs and provide additional cobenefits such as collection of cell salvage blood available for perfusion.

    This is the first review of studies on the environmental impact of cardiology practice. Others have noted the potential for ‘greener cardiology’.20 21 For example, in a review of the use of medical imaging in 10 diagnostic imaging categories (and 162 subcategories), it was found that the greatest opportunity to reduce energy consumption lay within cardiac imaging,21 highlighting, as we found, the scope to reduce the environmental impact of cardiac imaging by using lower energy consumption alternatives, such as echocardiography, as the first-line test, before considering CT or CMR imaging when clinically appropriate.

    Our study has important strengths and limitations to be considered. The strengths of our study include a broad and comprehensive search with independent double screening of title and abstracts and independent double extraction of data. We used a mixed-methods approach to extract and narratively synthesise the quantitative findings of the studies, together with a content analysis to provide additional insights through qualitative data extraction and analysis. An inherent limitation of this study is the small number of papers in this review which reflects the topical and novel nature of this research. The 12 studies selected are mainly from developed countries. Future studies in low-income and middle-income countries, with larger populations, may provide new insights into the environmental impact of cardiovascular healthcare. We may have missed some reports despite our broad search strategy, and new studies may have been published since our last search and will continue to emerge.

    With respect to study quality, reporting standards for environmental impact studies of healthcare have yet to be developed so we did not conduct a risk of bias assessment. LCA is a robust and reliable method that has been used in other sectors for many years, but to date has been little used in health research. Of note, only three studies in our review used LCA. The remainder used simpler approaches, ranging from an eco-audit to measuring product consumption, waste generation or distances travelled by patients to clinics. As such, these studies provide a less complete view of the environmental impacts of a product or service, but may still provide actionable information for clinicians. A priority in future work is to strengthen measurement quality in studies of the environmental impact of healthcare, and to couple this with stronger intervention study designs to assess clinical, environmental and economic outcomes.

    Our study highlights the scope of the environmental footprint of cardiology practice, and identifies some important implications for cardiologists to ‘green’ their practice. Further opportunities likely exist as part of a growing professional desire to transition to more sustainable healthcare without compromising health outcomes for patients. As an example, interventional cardiologists may conduct waste audits of their practice, which could support practice changes such as recycling packaging of catheters, balloons, stents and other equipment, or leveraging their purchasing power to encourage suppliers to reduce unnecessary packaging.

    The finding that the environmental footprint of international conferences is substantial may have implications for cardiology as a profession that convenes many conferences globally each year. Conference organisers could consider hybrid meetings (or alternate annual in person meetings with online meetings) to reduce their footprint, and provide social benefits—online meetings are more accessible to participants in low-income and middle-income countries, older participants, and those with disabilities. Teleconsultations may reduce emissions through less patient and doctor travel, and appear to provide social and economic cobenefits. However, research is needed to evaluate the impact of telehealth on health outcomes and on subsequent health service utilisation.

    Conclusions

    Within the context of cardiovascular healthcare, unnecessary tests and medicines have significant environmental impacts. Reducing unnecessary care is an important strategy for reducing the environmental impact of cardiac care. Cardiac imaging, monitoring, prescribing and in-hospital care including cardiac surgery all have important environmental impacts, however, many effective opportunities to reduce these exist, and provide economic, social and health cobenefits. Our review represents a first step into an emerging field. Further research is needed to investigate the environmental footprint of additional aspects of cardiology practice, to undertake intervention studies to discover ways to reduce the carbon footprint, and to establish the most effective ways to educate and raise awareness among cardiologists, nurses and other health professionals, about the environmental impact of cardiovascular healthcare.

    Data availability statement

    No data are available.

    Ethics statements

    Patient consent for publication

    Ethics approval

    Not applicable.

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    Supplementary materials

    • Supplementary Data

      This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

    Footnotes

    • Twitter @allyson_todd_, @CSHeartResearch

    • Contributors All authors were involved in study design, collection and analysis of selected papers, and writing the manuscript. AB is the guarantor.

    • Funding This work was supported by National Health and Medical Research Council funding to Barratt (#1104136) and Semsarian (#1154992).

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.