Context and Rationale
Tropical cyclones are severe weather phenomena that endanger certain regions worldwide each year. These weather events are called by different names depending on the location, such as hurricanes, typhoons, and cyclones, as classified by the World Meteorological Organization (WMO). 1 Over the past 50 years, tropical cyclones have caused numerous disasters, resulting in significant human and economic losses. 2 With climate change, the frequency and intensity of these extreme weather events are expected to increase.
Individuals with chronic comorbidities, such as respiratory disease, hypertension, and kidney disease, are at a higher risk for adverse health outcomes during and after tropical cyclones. This is because tropical cyclones can impact health through various behavioral, physical, and physiological pathways.Reference Lane, Charles-Guzman and Wheeler 3 For example, power outages can disrupt the use of respiratory equipment, leading to respiratory complications.Reference Parks, Anderson and Nethery 4 Furthermore, patients with respiratory illness may experience worsening symptoms due to the physical stress of cyclones, including high winds and exposure to harsh weather conditions.Reference D’Amato, Cecchi and D’Amato 5 For patients with kidney disease, damage to, or disruption of dialysis equipment due to lack of healthcare resources can interrupt dialysis treatments. Patients with high blood pressure may experience uncontrolled blood pressure due to a lack of medication. The psychological burden of disasters may also disrupt blood pressure control, a risk factor for patients with kidney diseases, including those receiving dialysis treatment.Reference Talge, Neal, Glover and Stress 6 Moreover, high blood pressure, also known as hypertension can be significantly impacted by the psychological stress,Reference Oparil, Acelajado and Bakris 7 and anxiety that result from natural hazards like tropical cyclones. This can potentially increase the risk of cardiovascular events and other health complications. The interaction between behavioral, physical, and psychological stressors highlights the increased vulnerability of individuals with chronic conditions during and after tropical cyclones.
The global all-age prevalence of chronic kidney disease (CKD) has risen by 29.3% since 1990, and kidney disease has a significant impact on global health, as it is a direct cause of morbidity and mortality worldwide.Reference Bikbov, Purcell and Levey 8 Tropical cyclones occur frequently, affect wide areas, and have significant impacts on patients with kidney disease. Observational studies have identified an increase in the initiation of dialysis following disasters, particularly due to hypertensive nephropathy.Reference Smith, Zucker and Frasso 9 Damage to infrastructure, such as electric utilities and backup generators, can lead to interruptions in treatment for patients requiring regular hemodialysis. The number of end-stage renal disease (ESRD) patients receiving maintenance hemodialysis (MHD) treatment is increasing annually. Tropical cyclones put MHD patients at risk, causing fluid overload, heart failure, and electrolyte disturbances due to missed scheduled dialysis sessions.Reference Ghazali, Guericolas and Thys 10 Patients who miss more than 3 sessions are at higher risk of hospitalization and developing posttraumatic stress disorder (PTSD).Reference Schrauben, Chen and Lin 11
Previous studies have revealed the unique vulnerabilities of hemodialysis patients during disasters, including tropical cyclones.Reference Parks, Anderson and Nethery 4 , Reference Chen, Tam and Cheung 12 Tropical cyclones often cause power outages and infrastructure damage, which can severely disrupt dialysis centers, posing major challenges for patients reliant on regular dialysis treatments.Reference Waddell, Jayaweera and Mirsaeidi 13 Access to essential care can be compromised during and after cyclones, resulting in missed or delayed dialysis sessions and subsequent health complications such as electrolyte imbalances, fluid overload, and toxin build-up.Reference Schrauben, Chen and Lin 11 Furthermore, the psychological stress of surviving a tropical cyclone can exacerbate patients’ existing health conditions, like hypertension, which is common among hemodialysis patients.Reference Waddell, Jayaweera and Mirsaeidi 13 These studies highlight the urgent need for disaster preparedness plans tailored to these patients’ needs, including resilient infrastructure, alternative power sources, and effective emergency notification strategies to ensure their well-being in cyclone-prone regions.
However, few studies have examined treatment-related problems after tropical cyclones or identified the primary reasons behind dialysis barriers for patients undergoing hemodialysis. Building on the findings of retrospective studies, this scoping review aims to fill these knowledge gaps by systematically mapping the research in this field.
The review will focus on the failure of patients to participate in hemodialysis regularly according to the prescribed regimen and assess the primary causes of treatment problems. This review will focus on the management of MHD patients during tropical cyclones, a critical subset of extreme weather events that have distinctive characteristics and pose specific challenges.
Purpose of the Current Review
Therefore, this study is a scoping review aiming to identify and summarize the problems and causes related to the treatment of patients with MHD in the aftermath of tropical cyclones, and provide actionable recommendations for contingency planning before, during, and after disasters. The rationale for employing a scoping review approach includes: (1) It can depict key concepts and synthesize available evidence when an area is complex or unexamined; (2) It summarizes findings for policymakers, patients, and healthcare workers who may lack time or resources to conduct reviews themselves; and (3) It can address management approaches related to patients on MHD during and after tropical cyclones and point to areas for further research.Reference Orach 14
Methods
Scoping Review Design
The study followed the methodology framework proposed by Arksey and O’Malley,Reference Arksey and O’Malley 15 which included 5 steps: (1) identifying the research questions, (2) identifying relevant studies, (3) study selection, (4) data extraction, and (5) data analysis and synthesis. The report follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) scoping review checklist extension (see Addendum 1).
Research Questions
In line with the objectives of this study and the observed impacts on MHD patients during or after tropical cyclones, we formulated our research questions to address the specific challenges and solutions for MHD patients during cyclones: (1) What are the treatment-related problems and causes faced by maintenance hemodialysis patients during or after tropical cyclones? (2) What is the nature of the recommendations made to eliminate/ mitigate the challenges?
Search Strategy
The search strategy sought to identify peer-reviewed studies published in English from January 1, 2000, to March 31, 2023. We searched 5 databases, including PubMed, Embase, and CINAHL Complete (EBSCO), as well as Web of Science, and Scopus. The search terms included hemodialysis, dialysis, renal replacement therapy, and ESRD, as well as tropical cyclones, hurricanes, typhoons, and cyclones. Other terms included storms, tornadoes, treatment, and therapy, as well as regimen. We used Boolean operators such as “AND” and “OR” to combine these keywords (See Addendum 2 for the search strategy).
Study Selection
Eligibility criteria
The inclusion criteria for including relevant studies to be reviewed were as follows: studies relevant to MHD during and after tropical cyclones were included in the review process. However, literature reviews, perspectives, conference abstracts, and gray literature were not included in this review.
Studies with the following characteristics were excluded: (1) Studies on tropical cyclones that did not analyze impacts on MHD in depth, and (2) Research on disasters during pandemics, which can cause widespread health problems and pose problems in the delivery of health care services.Reference Sever, Ortiz and Maggiore 16 Our focus is specifically on the direct effects of cyclones on MHD treatment facilities and patient care. Exclusions were applied consistently up to the final stage of data extraction, as typical in scoping studies.
Data Extraction
Data will be extracted independently by 2 researchers (FXY and LFZ), starting with an Excel spreadsheet to ensure that the table contains all relevant data about the study objectives. Data extraction, the title and abstract review, and full-text review will be split into 2 phases. Two researchers (FXY and LFZ) conducted the pilot study using 6 randomly selected eligible articles. Revisions were made by including additional unforeseen data generated from articles considered important to promote the review objectives. Disagreements will be resolved through discussion and, if necessary, consultation with an additional reviewer (SJL). Authors of individual studies will be contacted for more information if necessary (see Addendum 3).
Data Analysis and Synthesis
In this scoping review, we applied thematic analysis to dissect qualitative data from selected studies, taking inspiration from methodologies utilized in analogous disaster research.Reference Braun and Clarke 17 –Reference Dariagan, Atando and Asis 20 Themes emerged organically from the data on the impact of tropical cyclones on MHD patients. This approach ensured that each theme accurately reflected the core content of the studies. Our rigorous iterative review and refinement of the themes guaranteed a thorough understanding of the presented narratives. Our methodological stance facilitated a detailed examination of the specific challenges hemodialysis patients face during tropical cyclones, as well as the strategies devised to address them. Consequently, we pinpointed patterns and themes that accurately reflect the experiences and challenges of MHD in the context of tropical cyclones.
Results
Selection of Publications
The search produced 867 initial matches. After removing 325 duplicates, a total of 417 records that did not meet the inclusion criteria based on title and abstract screening were excluded. Of the remaining 125 full-text studies, a further 105 studies were excluded after full-text screening, leaving 19 studies for analysis (see Figure 1).
Publication and Study Characteristics
A total of 19 studies met the inclusion criteria for this scoping review, all of which analyzed the effects of tropical cyclones, including hurricanes and typhoons, on the treatment of hemodialysis patients. These studies spanned a range of geographic locations, such as the United States, Australia, and Puerto Rico, as well as Taiwan (see Table 1).
Collating, Summarizing, and Reporting Results
We reviewed and summarized the 19 studies based on the location where the tropical cyclone occurred, which included the United States, Puerto Rico, and Australia, as well as Taiwan. Table 1 summarizes the characteristics of tropical cyclones highlighted in the studies reviewed, their impact on dialysis treatment, the positive responses, and effective strategies identified in each disaster. This approach provides insights into how the selected studies addressed the cyclone impacts on dialysis care. It helps readers better understand the results and discussions presented in this study.
The studies were conducted in various regions, such as the United States, Australia, and Taiwan (see Table 1). They examined factors such as lack of access, insufficient electricity, inadequate disaster preparedness, and the consequences of hemodialysis interruptions, including delays, interruptions, and shorter treatment times. Patient-related, hospital-related, and community-related factors were identified as primary reasons for delays, and missed treatments, with hospital and community preparedness influencing dialysis disruptions, individual patient circumstances, and medical resource constraints affecting delays and missed treatments. Additionally, infrastructure and transportation played roles in both scenarios, with shorter treatment times linked to accommodating surges in patients’ needs.
Identification and Synthesis of Problems and Positive Aspects
Considering our qualitative analytical approach, thematic analysis was conducted to identify and synthesize the prominent issues and beneficial practices evident from the data.Reference Braun and Clarke 21 , Reference Vaismoradi, Turunen and Bondas 22 This allowed us to identify and synthesize the primary issues emerging in the wake of each tropical cyclone. The resulting thematic structure, presented in Table 2, was essential in deconstructing the complexity of the myriad problems documented across the literature.
To provide a comprehensive overview of the findings from this scoping review, which aims to address our primary research questions, Table 2 has been structured to go beyond documenting specific difficulties faced by MHD patients during tropical cyclones. The table summarizes a range of challenges and key manifestations identified in the study. This approach facilitates a more holistic understanding of the issues at hand, to enable deeper analysis of the broader implications and potential solutions in the field of disaster medicine and patient care.
Importantly, our analysis shows a strong link between all successful measures and the response phase of comprehensive emergency management (see Figure 2). 23 , 24 We have therefore expanded the scope from immediate response strategies to include “effective disaster risk reduction (DRR) ” measures.Reference Twigg 25 This approach ensures comprehensive coverage of strategies applicable to all phases of disaster management, including mitigation, preparedness, and response as well as recovery.
Unveiling the Impact of Tropical Cyclones on Hemodialysis Treatment
Research question 1
What are the treatment-related problems and causes faced by MHD patients during or after tropical cyclones?
In response to the first research question, selected studies unveiled a spectrum of treatment-related challenges experienced by dialysis patients in the aftermath of tropical cyclones. These challenges included disruptions in dialysis services, limited access to medicines and medical services, transportation difficulties, and inadequate disaster planning, as detailed in Table 1. Notably, factors such as power outages and traffic disruptions contribute to patients frequently missing dialysis sessions. Approximately 50% of the studies indicated a subsequent increase in hospitalizations,Reference Abir, Jan and Jubelt 32 –Reference Anderson, Cohen and Kutner 33 , Reference Dossabhoy, Qadri and Beal 35 , Reference Lempert and Kopp 37 –Reference Lin, Pierce and Roblin 38 , Reference Rivera-Hernandez, Kim and Nguyen 42 –Reference Blum, Feng and Anderson 44 with a small number mentioning patient deaths.Reference Avilés Mendoza, Finne and Torre Leon 41 –Reference Lukowsky, Dobalian and Kalantar-Zadeh 43
To systematically explore and address the challenges identified, we summarized a series of issues in 3 different underlying themes in the field of dialysis care during tropical cyclones (see Table 2). This comprehensive analysis aims to identify key themes and potential patterns in these issues, highlighting the complex landscape of dialysis patient care in the aftermath of such an event. Our survey of these areas revealed important insights into the state of preparedness and response, highlighting the need for a robust strategy in the face of tropical cyclones.
In our scoping review, thematic analysis was employed for qualitative analysis. This involved systematically coding the collected data to identify recurring themes and patterns. Each theme was thoroughly analyzed to understand its significance in the context of the impact of tropical cyclones on maintenance hemodialysis patients. This qualitative summary provides an in-depth understanding of the challenges and strategies identified in the literature.
After thoroughly examining and synthesizing the research, the team focused on 3 overarching themes that represent the challenges faced by dialysis patients after tropical cyclones. Table 2 provides a detailed description of these themes: the fragile state of preparedness identified in the research, which is summarized into 3 agreed-upon themes; hemodialysis health-related challenges; socially relevant challenges; and challenges of management inefficiencies.
Research question 2
What is the nature of the recommendations made to eliminate/ mitigate the challenges?
Table 3 addresses our second research question on the recommendations for mitigating the challenges faced by patients with MHD during tropical cyclones. The recommendations are informed by the effective strategies and positive aspects observed in Table 1 (see Table 3). In this context, the recommendations specifically targeted MHD patients, addressing the unique challenges and needs they face during tropical cyclones. The community was engaged in preparing for cyclones, implementing safeguards, fostering cross-sectoral collaboration, and coordinating with hospitals. The roles of hospitals and communities were explored, focusing on preparations before cyclones, and ensuring medical treatment for patients during such events.
Additionally, the researchers categorized the recommendations into 4 target phases based on relevant measures during and before tropical cyclones. These effective Disaster Risk Reduction (DRR) practices include fortifying healthcare infrastructure, emergency plan development, activation of emergency healthcare services, and intersectoral collaboration for rebuilding.
Furthermore, 16 actionable recommendations were identified and distributed across 4 target disaster phases aligned with comprehensive emergency management: the ‘mitigation phase,’ ‘preparedness phase,’ ‘response phase,’ and ‘recovery phase’ (see Table 3). This framework highlights strategic measures to address the challenges faced by MHD patients, covering the entire spectrum of a tropical cyclone’s impact, including the preparatory, and reconstruction phases. This comprehensive approach facilitates a thorough understanding of the unique difficulties encountered before, during, and after tropical cyclones.
Discussions
As far as we know, this is the first scoping review of its kind, offering a comprehensive exploration of post-tropical cyclone care complexities for MHD patients, and the key factors contributing to these challenges. Although the review focuses on data from high-income countries, the central themes and insights extracted from the review have broad applicability across diverse contextual and environmental settings. This review provides critical insights and valuable lessons in this domain, particularly highlighting that the primary causes of treatment-related issues often revolve around healthcare infrastructure and community dynamics.
Of the types of responses that are effective, those adopted by health systems have been more widely explored in studies, and most of these measures are related to local health systems.Reference Kaiser, Karaye and Olokunlade 27 –Reference Bonilla-Félix and Suárez-Rivera 29 , Reference McArdle 31 –Reference Johnson, Hayes and Gray 36 , Reference Lin, Pierce and Roblin 38 –Reference Lukowsky, Dobalian and Goldfarb 39 , Reference Avilés Mendoza, Finne and Torre Leon 41 , Reference Lukowsky, Dobalian and Kalantar-Zadeh 43 In this review, we categorized the identified best practices into 2 main groups: ’Effective response strategies’ and ’Recommendations for future preparedness.’ This classification enhances understanding in 2 key areas. First, it clarifies the successful actions taken during tropical cyclones. Second, it outlines suggested improvements for future disaster readiness for MHD patients. Hence, based on these classifications, countries can adopt the outlined recommendations. This will enable them to initiate new contingency plans and develop interim strategies, ensuring more comprehensive protection for MHD patients.
Effective Response Strategies for MHD Patients During Tropical Cyclones
In our analysis, we concentrated on identifying specific gaps in disaster preparedness and response for MHD patients, as well as highlighting effective strategies and positive practices observed during tropical cyclones. Challenges emerging during and after tropical cyclones are categorized into 3 principal domains: hemodialysis health-related challenges, socially relevant challenges, and challenges of management inefficiencies. Hemodialysis health-related challenges constitute the primary focus of our discussions (89%).Reference Mellgard, Abramson and Okamura 26 –Reference Lukowsky, Dobalian and Goldfarb 39 , Reference Avilés Mendoza, Finne and Torre Leon 41 –Reference Lukowsky, Dobalian and Kalantar-Zadeh 43 These challenges predominantly manifest as delayed hemodialysis treatment, treatment interruptions, as well as shortened hemodialysis times, and stem from power failures, water cutoffs, transportation disruptions, and breakdowns in medical infrastructure induced by tropical cyclones.
Our findings align with a 2022 US cohort study, underscoring the heightened vulnerability of patients undergoing dialysis to hurricanes, particularly maintenance dialysis patients who face an elevated risk of death within 30 days after hurricane events.Reference Rivera-Hernandez, Kim and Nguyen 42 This emphasizes the health risks posed to dialysis patients due to local exposure to tropical cyclones. In prolonged tropical cyclone scenarios, patients may confront additional risks, including missed dialysis sessions, and inadequate treatment, as well as complications leading to hospitalization, infection risks, and challenges accessing medications. This correlation is consistent with observations from Hurricane Katrina, where 44% of affected patients missed at least 1 dialysis session, 17% missed at least 3, and 23% of patients were hospitalized within a month post-hurricane.Reference Kelman, Finne and Bogdanov 45 , Reference Li, Staneva and Bidlot 46
In the realm of socially relevant challenges, the primary cause of dialysis disruption for maintenance hemodialysis patients stems from healthcare infrastructure challenges induced by tropical cyclones, as well as disruptions in transportation, and electric power. Studies on the impact of disasters on hemodialysis patients in the Americas, exemplified by Oquendo et al. (2023),Reference Oquendo, Friend and Halberstam 47 indicate that disasters can result in power shortages, lack of clean water, and disruptions in traffic. Mass evacuations and environmental disturbances further lead to the closure of dialysis centers, a surge in dialysis patients at these centers, and increased instances of missed dialysis treatments.Reference Oquendo, Friend and Halberstam 47 , Reference Pisano, Bohmer and Edmondson 48
As we delve deeper into these challenges, a potential issue surfaces: challenges of management inefficiencies (74%),Reference Bonilla-Félix and Suárez-Rivera 29 –Reference Anderson, Cohen and Kutner 33 , Reference Dossabhoy, Qadri and Beal 35 –Reference Lin, Pierce and Roblin 38 , Reference Murakami, Siktel and Lucido 40 –Reference Blum, Feng and Anderson 44 primarily manifested in inadequate disaster. A cross-sectional study emphasizes the need to enhance management efficiency and disaster preparedness to ensure hemodialysis patients are prepared for emergency dialysis.Reference Kopp, Ball and Cohen 49 Similarly, a study in North Carolina highlights that only about 42% of patients receiving dialysis were adequately prepared for emergency dialysis, corroborating our study findings.Reference Foster, Brice and Shofer 50
Significant Scopes of Efficient Response Measures
Table 3 shows effective strategies for individuals, hospitals, and communities across 4 themes, with the most explored being fortifying healthcare infrastructure and emergency plan development. By developing a comprehensive emergency plan, dialysis facilities can identify alternative facilities and backup power sources in disasters, power outages, or other emergencies. This proactive approach helps maintain continuity of care for hemodialysis patients and reduces the risk of treatment interruption. For example, in 2016, a study by Connealy et al.Reference Connealy, Lew and Alsamman 51 found that dialysis facilities with contingency plans experienced fewer treatment interruptions during disasters compared to dialysis facilities without contingency plans. Similarly, in 2018, a study by Kim et al.Reference Kim 52 highlighted the importance of identifying alternative dialysis facilities, and having adequate backup power sources to ensure continuity of care during emergencies. Therefore, a comprehensive emergency plan for dialysis facilities should include identifying potential risks and hazards, developing emergency protocols, and establishing clear communication channels with patients, staff, and emergency responders. In addition, dialysis facilities should conduct regular training sessions and drills to ensure staff are prepared to implement emergency plans when necessary.Reference Singh and Tuomainen 53
The development of personal disaster plans at the community and individual levels is considered an effective strategy. Studies have shown that hemodialysis patients with personal disaster plans are more likely to experience fewer treatment interruptions and are better able to manage their medical needs during disasters.Reference Nihonyanagi, Tsukasaki and Itatani 54 Personal disaster plans should be tailored to the specific medical needs of hemodialysis patients and should include necessary emergency supplies, medications, medical equipment, and important documents such as medical records, insurance information, and emergency contact information.Reference Mellgard, Abramson and Okamura 26 , Reference Lukowsky, Dobalian and Goldfarb 39 –Reference Rivera-Hernandez, Kim and Nguyen 42
Moore et al. also emphasized prioritizing health system responses, highlighting the importance for decision-makers and administrators to focus on the 4 phases of emergency management.Reference Moore, Mawji and Shiell 55
Important Insights from the Recommendations
The included studies underscore the critical importance of emergency preparedness, communication, and collaboration among stakeholders in mitigating the impact of tropical cyclones on hemodialysis patients (78%).Reference Kaiser, Karaye and Olokunlade 27 –Reference Lukowsky, Dobalian and Goldfarb 39 , Reference Avilés Mendoza, Finne and Torre Leon 41 , Reference Lukowsky, Dobalian and Kalantar-Zadeh 43 Effective collaboration and partnerships, proven vital in responding to disasters affecting various healthcare domains, are similarly crucial for dialysis facilities. Actively engaging with utilities, local emergency operation centers, hospitals, and transport companies, as well as health departments, is imperative to ensure the appropriate care and treatment for hemodialysis patients during and after disasters. For instance, studies like Kenney RJ’s in 2007,Reference Kenney 56 emphasize the significance of collaborating with local hospitals and emergency responders to guarantee that hemodialysis patients receive optimal care. Similarly, research by Jain et al.Reference Jain, Temming and D’Alton 57 in 2017, underscores the benefits of partnering with transport companies to facilitate the transfer of hemodialysis patients to alternative dialysis facilities during emergencies.
Limitations
This scoping review’s primary limitations include its focus on high-income countries and hemodialysis, potentially overlooking diverse treatment contexts and definitions of treatment-related issues. Consequently, it may not fully represent the challenges in low-income settings, where resource constraints significantly impact healthcare system responses to tropical cyclones. Future research should expand to include various kidney disease treatments, like peritoneal dialysis and kidney transplantation, and examine the broader mental health impacts of disasters on MHD patients. Additionally, exploring emergency planning in varied economic contexts is crucial for developing comprehensive disaster preparedness strategies. This scoping review underscores the need for further investigation into these diverse and complex settings.
Recommendations
The findings could help inform further systematic reviews on the impact of tropical cyclones on MHD patients. There is a lack of data and information on MHD in disasters in low-and middle-income countries (LMICs), highlighting the need for enhanced, reliable, and accurate data collection in LMICs. To help inform policymaking and financing for MHD patients in disasters.
Conclusion
This scoping review provides a comprehensive understanding of the treatment-related problems faced by MHD patients during and after tropical cyclones, along with the primary causes of these problems. The review underscores the critical role of water, electricity, healthcare facilities, and dialysis centers in ensuring the provision of dialysis and the critical need for patients to adhere to prescribed hemodialysis sessions. The review also provides emergency planning countermeasures and recommendations to improve the continuity of dialysis treatment for MHD patients before and after a tropical cyclone. The results underline the vital role of medical staff in emergency preparedness and the prompt activation of contingency plans during disasters to tackle treatment-related issues. Despite some limitations, this review makes a valuable contribution to our understanding of the challenges MHD patients face after tropical cyclones. Implementing the recommended countermeasures can significantly mitigate the impact of disasters on patients with kidney disease.
Abbreviations
- CKD
-
Chronic kidney disease
- DRR
-
Disaster Risk Reduction
- ESRD
-
End-stage renal disease
- LMICs
-
Low-and middle-income countries
- MHD
-
Maintenance hemodialysis
- PTSD
-
Posttraumatic stress disorder
- WMO
-
World Meteorological Organization
Supplementary material
The supplementary material for this article can be found at http://doi.org/10.1017/dmp.2024.70.
Data availability statement
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation, to any qualified researcher.
Funding statement
No funding was received for this study.
Competing interest
This manuscript has not been submitted or accepted for publication elsewhere. The paper is not based on previous communication with a society or meeting. All authors have seen and approved the content and have contributed significantly to the work. The authors declare no potential competing interest.