Archive for category: BJUI Blog

Editorial: Can machine‐learning algorithms replace conventional statistics?

Wong et al. [1] evaluate 19 clinical variables (training data) and three supervised machine‐learning algorithms to predict early biochemical recurrence after robot‐assisted prostatectomy. They further compare the areas under the curve (AUCs) resulting from these algorithms with the AUC of a conventional Cox regression model and conclude that the machine‐learning algorithms can produce accurate disease prognosis, perhaps better than a traditional Cox regression model. As the authors state, predictive models have the potential to better individualize care to patients at highest risk of prostate cancer recurrence and progression.

The authors should be commended for their adoption of machine‐learning algorithms to better interpret the vast volumes of clinical data and assess prognosis after robot‐assisted prostatectomy. This should represent another step forward for the management of prostate cancer, where tailored treatment is now largely based on the clinical risk stratification of the disease [2]. Incidentally, we are also in an era where we are seeing aspects of artificial intelligence (machine learning being a subset of it) vastly transform how we view and process data in everyday life. This has been true in medicine as well, particularly for prostate cancer [3].

While our own research group has also evaluated machine‐learning algorithms to process surgeon performance metrics and predict clinical outcomes after robot‐assisted prostatectomy [4], I want to express a word of caution. Utilization of machine learning does not in itself imply automatic superiority over conventional statistics [5] despite literature that has demonstrated so [3]. The success of predictive models in machine learning still relies on the quality of data introduced and careful execution of the analysis. In our experience, it works best when highly experienced clinicians and data scientists are working hand in hand.

Furthermore, I would argue that the results of this present study do not necessarily show that machine learning is superior to conventional statistics, but rather it highlights an inherent advantage of machine learning. While traditional analyses require the a priori selection of a model based on the available data, machine learning has more flexibility for model fitting [6]. Additionally, inclusion of variables in traditional analyses is constrained by the sample size. In contrast, by design, machine learning models thrive on their ability to consider many variables concurrently, and as such, have the potential to detect underlying patterns that may otherwise be undetectable when data are examined effectively in individual silos.

We look forward to the external validation of the methodology described in the present article. Big and diverse data are critical requirements of machine learning. A multi‐institutional, multi‐surgeon cohort is necessary to confirm the findings in this report. A further step from there is the adoption of such prediction models into clinical use. The ultimate question is how improved prognostic data may influence surgeon and patient decisions.

Conflict of Interest

Dr Hung reports personal fees from Ethicon, Inc, outside the submitted work.


  1. Wong NC, Lam C, Patterson L, Shayegan B. Use of machine learning to predict early biochemical recurrence following robotic prostatectomy. BJU Int 2019; 123: 51–7
  2. D’Amico AV, Whittington R, Malkowicz SB et al. Biochemical outcome after radical prostatectomy, external beam radiation therapy or interstitial radiation therapy for clinically localized prostate cancer. JAMA 1998; 280: 969–74
  3. Hung AJ, Chen J, Che Z et al. Utilizing machine learning and automated performance metrics to evaluate robot‐assisted radical prostatectomy performance and predict outcomes. J Endourol 2018; 32: 438–445
  4. Kattan MW. Comparison of Cox regression with other methods for determining prediction models and nomograms. J Urol 2003; 170 (6 Pt 2): S6–9
  5. Hung AJ, Chen J, Gill IS. Automated performance metrics and machine learning algorithms to measure surgeon performance and anticipate clinical outcomes in robotic surgery. JAMA Surg 2018; 153: 770–1

January 2019 – About the cover

The first article of the month for 2019 is from McMaster University, Hamilton, Ontario, Canada: Use of machine learning to predict early biochemical recurrence following robotic prostatectomy.

McMaster University is the 4th best in Canada and makes number 77 in the Times Higher-Education rankings 2018-19. It introduced (in 1965) an accelerated three-year MD programme with classes all year round and in the 1980s the phrase “evidence-based medicine” was coined here.

Hamilton is a port town on Lake Ontario. It is split into two by the Niagara escarpment which runs through the metropolitan area, and it has more than 100 waterfalls.


Residents’ podcast: Cluster analysis of multiple chronic conditions associated with urinary incontinence among women in the USA

Giulia Lane M.D. and Iryna Crescenze M.D. are Fellows in Neuro-urology and Pelvic Reconstruction in the Department of Urology at the University of Michigan.

In this podcast they discuss the following BJUI Article of the Week:

Cluster analysis of multiple chronic conditions associated with urinary incontinence among women in the USA



To identify patterns of prevalent chronic medical conditions among women with urinary incontinence (UI).

Materials and Methods

We combined cross‐sectional data from the 2005–2006 to 2011–2012 US National Health and Nutrition Examination Surveys, and identified 3 800 women with UI and data on 12 chronic conditions. Types of UI included stress UI (SUI), urgency UI (UUI), and mixed stress and urgency UI (MUI). We categorized UI as mild, moderate or severe using validated measures. We performed a two‐step cluster analysis to identify patterns between clusters for UI type and severity. We explored associations between clusters by UI subtype and severity, controlling for age, education, race/ethnicity, parity, hysterectomy status and adiposity in weighted regression analyses.


Eleven percent of women with UI had no chronic conditions. Among women with UI who had at least one additional condition, four distinct clusters were identified: (i) cardiovascular disease (CVD) risk‐younger; (ii) asthma‐predominant; (iii) CVD risk‐older; and (iv) multiple chronic conditions (MCC). In comparison to women with UI and no chronic diseases, women in the CVD risk‐younger (age 46.7 ± 15.8 years) cluster reported the highest rate of SUI and mild UI severity. In the asthma‐predominant cluster (age 51.5 ± 10.2 years), women had more SUI and MUI and more moderate UI severity. Women in the CVD risk‐older cluster (age 57.9 ± 13.4 years) had the highest rate of UUI, along with more severe UI. Women in the MCC cluster (age 61.0 ± 14.8 years) had the highest rates of MUI and the highest rate of moderate/severe UI.


Women with UI rarely have no additional chronic conditions. Four patterns of chronic conditions emerged with differences by UI type and severity. Identification of women with mild UI and modifiable conditions may inform future prevention efforts.

Read the full article

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Four Seasons – Autumn’s Top Reviewer

This month, BJUI continues the Four Seasons Peer Reviewer Award recognising the hard work and dedication of our peer reviewers. Each quarter the Editor and Editorial Team  select an individual peer reviewer whose reviews over the last 3 months have stood out for their quality and timeliness.

The Autumn Crown goes to Nicholas Raison.

Nicholas Raison is Urology Specialist Registrar in the North London Deanery and Vattikuti Research Fellow at King’s College London. Alongside clinical urology, Nicholas’ academic interests include medical education and surgical innovation. He is a Fellow of the Higher Education Academy and is currently completing a PhD on a pan-European project on the validation and assessment of robotic simulation training.


December 2018 – About the cover

The article of the month for December 2018 is on work carried out in Guangzhou, China: Super‐mini percutaneous nephrolithotomy vs retrograde intrarenal surgery for the treatment of 1–2 cm lower‐pole renal calculi: an international multicentre randomised controlled trial.

Guangzhou, on the River Pearl, is the capital of Guangdong in Southern China. It is a major port and transportation hub, and was known as Canton to early European traders. The current population is estimated to be >13 million making it China’s third largest city. The climate is sub-tropical monsoon giving hot humid Summers and mild dry Winters and a city blooming with flowers all year round.

©Prokar Dasgupta

Urodynamics is acceptable and well-tolerated but best practice is not always provided: lessons from male patients interviewed during the UPSTREAM trial

In a recently published qualitative study, we found that urodynamic testing was acceptable to men with lower urinary tract symptoms (LUTS), despite some reporting apprehension, discomfort or embarrassment and, at times, inadequate provision of information. Men’s experiences of urodynamics highlight ways in which clinical practice can be improved, including better communication about what to expect during and after the test, minimising embarrassment by ensuring privacy, and timely discussion of test results in sufficient detail.

Ninety percent of men aged 50‐80 live with at least one LUTS, which can negatively impact quality of life. LUTS prevalence and severity increase with age, and with demographic aging the management of LUTS is an increasing priority. Urodynamics with invasive multichannel cystometry is widely used when medications haven’t successfully relieved symptoms and surgery for bladder outlet obstruction is being considered. But there is ongoing debate about the extent to which urodynamics should be used, reflecting lack of evidence regarding the effectiveness of urodynamics and how acceptable it is to patients.

What we did

The Urodynamics for Prostate Surgery: Randomised Evaluation of Assessment Methods (UPSTREAM) randomised controlled trial is a 4-year study funded by the National Institute of Health Research Health Technology Assessment Programme (UK). The trial randomised 820 men with LUTS from urology departments in 26 hospitals in England to either a care pathway consisting of non-invasive routine tests, or one of routine tests plus urodynamics. At 18-months after randomisation, UPSTREAM assessed the effect of urodynamics on symptoms and rates of surgery in men with bothersome LUTS seeking further treatment.

In a large qualitative study nested within the UPSTREAM trial, we explored men’s attitudes to and experiences of urodynamics, to provide in‐depth qualitative evidence to inform clinical practice. We interviewed a diverse group of 41 men with LUTS, including those who had had urodynamics and those who had not.


What we found

  • All 25 men who underwent urodynamics reported that it was acceptable.
  • Of the 16 men who had not had urodynamics previously, 14 said they would have been willing to have it if needed (with four reporting some apprehension), while two said they would want more information about the test and its purpose.
  • Among patients who had had urodynamics, the test was well-tolerated, although there was variation in how uncomfortable men found it. Some men experienced short-lived negative after-effects (e.g. stinging, a urinary tract infection), but despite these issues said they would willingly have the test again.
  • A minority of men reported embarrassment, due to the intimate nature of urodynamics or not being prepared for its effects (e.g. spraying while urinating).
  • Embarrassment also depended on the degree of privacy available, including the number of people in the room during the test, room location and size (a larger room near a busy corridor was more socially awkward).
  • Patients valued urodynamics for its diagnostic insight, perceiving it as more informative than other tests. Patients felt that having urodynamics meant they had received all the investigative tests available and so had all possible facts regarding their condition.
  • Patients described gaps in the information provided by clinicians before, during, and after the test; for example, what to expect when the test was conducted and what the test results meant.
  • How and when results were explained varied: explanations were given during the test by the technician or nurse undertaking it, from a doctor straight after receiving the test, or at a separate appointment with a doctor a short time later. Men appreciated it when test results were available and discussed with a clinician immediately after the test.
  • While most men were satisfied with clinicians’ explanation of the results of urodynamics, this was not universal; rushed explanations were highlighted as problematic.


Based on men’s experiences, we recommend:

  1. Good communication before and during the procedure, in line with patient preferences, to ensure patients are well prepared and informed.
  2. Prioritising patient privacy, including minimising the number of people present during the test and introducing the staff members who are present.
  3. Discussing test results with patients promptly, in the amount of detail they wish.
  4. Training and guidance for urology clinicians and urodynamics technicians in these areas.


We acknowledge and thank the patients and clinicians involved in the UPSTREAM trial as well as the NHS trusts involved. This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) program (project number 12/140/01). This study was designed and delivered in collaboration with the Bristol Randomised Trials Collaboration (BRTC), a UKCRC registered clinical trials unit which, as part of the Bristol Trials Centre, is in receipt of National Institute for Health Research CTU support funding. The views and opinions expressed are those of the authors and not necessarily those of the HTA program, NIHR, NHS, or the Department of Health and Social Care.


About the authors: 

Dr Selman and Dr Horwood are Senior Research Fellows at University of Bristol, specialising in qualitative research in randomised trials. Twitter: @Lucy_Selman, @JPHorwood

Prof Drake is Professor of Physiological Urology at Bristol Urological Institute, North Bristol NHS Trust, and at Translational Health Sciences, Bristol Medical School, University of Bristol. Twitter: @MarcusDrakeUrol, @UroweESU

Dr Amanda Lewis is a Clinical Trial Manager at the University of Bristol, currently working in the area of Urology research. Twitter: @ALBrooks2015


Residents’ podcast: Urinary, bowel and sexual health in older men from Northern Ireland

Maria Uloko is a Urology Resident at the University of Minnesota Hospital and Giulia Lane is a Female Pelvic Medicine and Reconstructive Surgery Fellow at the University of Michigan.

In this podcast they discuss the following BJUI Article of the Week:

Urinary, bowel and sexual health in older men from Northern Ireland

David W. Donnelly*, Conan Donnelly†, Therese Kearney*, David Weller‡, Linda Sharp§, Amy Downing¶, Sarah Wilding¶, PennyWright¶, Paul Kind**, James W.F. Catto††, William R. Cross‡‡, Malcolm D. Mason§§, Eilis McCaughan¶¶, Richard Wagland***, Eila Watson†††, Rebecca Mottram¶, Majorie Allen, Hugh Butcher‡‡‡, Luke Hounsome§§§, Peter Selby, Dyfed Huws¶¶¶, David H. Brewster****, EmmaMcNair****, Carol Rivas††††, Johana Nayoan***, Mike Horton‡‡‡‡, Lauren Matheson†††, Adam W. Glaser and Anna Gavin*

*Northern Ireland Cancer Registry, Centre for Public Health, Queen’s University Belfast, Belfast, UK, †National Cancer Registry Ireland, Cork, Ireland, ‡Centre for Population Health Sciences, University of Edinburgh, Edinburgh, UK, §Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK, Leeds Institute of Cancer and Pathology/Leeds Institute of Data Analytics, University of Leeds, Leeds, UK, **Institute of Health Sciences, University of Leeds, Leeds, UK, ††Academic Urology Unit, University of Sheffield, Sheffield, UK, ‡‡Department of Urology, St James’s University Hospital, Leeds, UK, §§Division of Cancer and Genetics, School of Medicine, Velindre Hospital, Cardiff University, Cardiff, UK, ¶¶Institute of Nursing and Health Research, Ulster University, Coleraine, UK, ***Faculty of Health Sciences, University of Southampton, Southampton, UK, †††Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, UK, ‡‡‡Yorkshire Cancer Patient Forum, c/o Strategic Clinical Network and Senate, Yorkshire and The Humber, Harrogate, UK, §§§National Cancer Registration and Analysis Service, Public Health England, Bristol, UK, ¶¶¶Welsh Cancer Intelligence and Surveillance Unit, Cardiff, UK, ****Information Services Division, NHS National Services Scotland, Edinburgh, UK, ††††Department of Social Science, UCL Institute of Education, University College London, London, UK, and ‡‡‡‡Psychometric Laboratory for Health Sciences, Academic Department of Rehabilitation Medicine, University of Leeds, Leeds, UK

Read the full article



To provide data on the prevalence of urinary, bowel and sexual dysfunction in Northern Ireland (NI), to act as a baseline for studies of prostate cancer outcomes and to aid service provision within the general population.

Subjects and Methods

A cross‐sectional postal survey of 10 000 men aged ≥40 years in NI was conducted and age‐matched to the distribution of men living with prostate cancer. The EuroQoL five Dimensions five Levels (EQ‐5D‐5L) and 26‐item Expanded Prostate Cancer Composite (EPIC‐26) instruments were used to enable comparisons with prostate cancer outcome studies. Whilst representative of the prostate cancer survivor population, the age‐distribution of the sample differs from the general population, thus data were generalised to the NI population by excluding those aged 40–59 years and applying survey weights. Results are presented as proportions reporting problems along with mean composite scores, with differences by respondent characteristics assessed using chi‐squared tests, analysis of variance, and multivariable log‐linear regression.


Amongst men aged ≥60 years, 32.8% reported sexual dysfunction, 9.3% urinary dysfunction, and 6.5% bowel dysfunction. In all, 38.1% reported at least one problem and 2.1% all three. Worse outcome was associated with increasing number of long‐term conditions, low physical activity, and higher body mass index (BMI). Urinary incontinence, urinary irritation/obstruction, and sexual dysfunction increased with age; whilst urinary incontinence, bowel, and sexual dysfunction were more common among the unemployed.


These data provide an insight into sensitive issues seldom reported by elderly men, which result in poor general health, but could be addressed given adequate service provision. The relationship between these problems, raised BMI and low physical activity offers the prospect of additional health gain by addressing public health issues such as obesity. The results provide essential contemporary population data against which outcomes for those living with prostate cancer can be compared. They will facilitate greater understanding of the true impact of specific treatments such as surgical interventions, pelvic radiation or androgen‐deprivation therapy.

Read more Articles of the week


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Reaching for the stars – rating the quality of systematic reviews with the Assessment of Multiple Systematic Reviews (AMSTAR) 2

The number of published systematic reviews and meta‐analyses in the urological literature has dramatically increased in recent years [1]. This is good news given their importance in guiding clinical decision‐making, guideline development and health policy. However, many of these studies are of low quality, raising concerns about the trustworthiness of their results. As with other research studies, it is therefore important for readers to have a framework for determining the quality of a given systematic review. Therefore, in 2017 BJU International launched a scoring system for systematic reviews that provides readers with a summary assessment as to whether established methodological safeguards against bias for systematic reviews have been met [2]. This is based on the Assessment of Multiple Systematic Reviews (AMSTAR), a validated instrument that assesses methodological quality on an 11‐point scale (0–11), with higher scores reflecting greater methodological rigor and all criteria being given the same relative weight [3].

Recently, an updated version of this instrument has become available, offering a better assessment of systematic reviews [4]. The revised instrument (AMSTAR 2) includes 10 of the original domains; it has 16 items in total (compared with 11 in the original), simpler response categories to the original AMSTAR, and provides an overall rating that is largely based on seven critical domains that should all be met. These relate to: (i) documentation of an a priori registered protocol in Prospective Register of Systematic Reviews (PROSPERO) or through Cochrane, (ii) a comprehensive literature search, (iii) explicit justification for excluding studies, (iv) a risk of bias assessment of included studies, (v) appropriate use of meta‐analytical methods, (vi) consideration of risk of bias when interpreting the results of the review, and (vii) assessment of presence and likely impact of publication bias. Other, non‐critical domains include a clear description of the study question in Population, Intervention, Comparison, Outcome (PICO) format, study selection and data extraction in duplicate, and identification of sources of funding of the studies included in the review and the review itself. This results in a four‐tiered rating (high, moderate, low, and critically low) that reflects the confidence that a reader may place in the results. Notably, a high‐quality rating requires no critical weakness and allows for only one non‐critical weakness. More than one non‐critical weakness drops the rating down to moderate, and just one critical weakness (such as lack of an a priori protocol) drops the rating down to low. Any review that has more than one critical weakness will be rated as critically low.

BJU International editors will routinely apply this AMSTAR 2‐based scoring system to screen for methodological quality in order to raise the awareness of this issue and promote reviews of higher quality (Fig. 1)[1]. Needless to say, BJU International is not the place for systematic reviews of sub‐optimal methodological quality in which the readers cannot place their trust. Meanwhile, we also fully understand that methodological rigor is not everything but has to be paired with clinical relevance and newsworthiness. Much has been written about the dramatic redundancy of systematic reviews on the same topic; in certain areas of medicine, the number of systematic reviews exceeds that of eligible studies that these reviews included [5]. Therefore, when systematic reviews already exist, there needs to be a clear rationale for any ‘encore’ performance. BJU International also encourages the development of systematic reviews by author teams that are financially unconflicted and have thoughtfully managed any intellectual conflict of interest.

Figure 1: New BJUI rating system of systematic reviews based on AMSTAR 2. The number of coloured stars in the inner and outer layers of the system represents completeness of an individual critical domain and overall confidence rating of the systematic review, respectively. The number in the middle of the system refers to the summary AMSTAR 2 score based on the overall confidence rating of the systematic review (high: 4, moderate: 3, low: 2, critically low: 1).

Through this initiative, BJU International not only intends to become the premier journal for high‐quality systematic reviews as they relate to urology, but also to move the field forward, reducing redundancy and waste. As we embrace the higher standards of AMSTAR 2, we present the first review to be scored using this method in this issue [6] and we encourage all systematic review authors to accept this challenge and reach with us for the stars.


  1. Han JL, Gandhi S, Bockoven CG, Narayan VM, Dahm P. The landscape of systematic reviews in urology (1998 to 2015): an assessment of methodological quality. BJU Int 2017; 119: 638–49
  2. Dahm P. Raising the bar for systematic reviews with Assessment of Multiple Systematic Reviews (AMSTAR). BJU Int 2017; 119: 193
  3. Shea BJ, Grimshaw JM, Wells GA et al. Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews. BMC Med Res Methodol 2007; 7: 10


About the authors:

Dr Philipp Dahm is Professor of Urology and Vice Chair of Veterans Affairs at the University of Minnesota. He also serves as Director of Research and Education for Surgical Services at the Minneapolis Veterans Administration Medical Center (@EBMUrology).


Dr Jae Hung Jung is from the Department of Urology, Wonju College of Medicine, Yonsei University, Korea.




Dr Daniel Christidis 1986-2018: A Rising Star Lost Far Too Soon

Dan was lost to us on Monday 5th November, 2018 after a fatal shark attack at Cid Harbour in the Whitsunday Islands, Queensland, Australia. Dan was surrounded by friends, many of them medical, who tried valiantly to resuscitate him. Other bystanders and the Queensland rescue team managed to assist in retrieving him to the nearest trauma hospital but nothing further could be done despite all best efforts.

This blog in the BJUI, a journal Dan contributed to in many ways (blogs, articles, creating projects) is a celebration of his life, and an opportunity for those who knew Dan directly or indirectly to post their own special memory of him, and to post a tribute to one of the rising stars of urology.


Daniel was a remarkable person- a unique individual who touched so many with his charm, style and intellect. He will be missed by so many – the world has been robbed of one of its true shining stars that was only beginning to rise.

D​an​ wore so many hats – doctor, researcher, young urologist, ​mentor, ​international contributor and organiser to name a few. ​he has been described as having a ​‘Heart of ​g​old’ ​and this​ is absolutely true for those who ​k​new him​. ​ ​Th​e fact that the Victorian State Health Minister was moved to comment on what a loss his tragic death is speaks volumes for his impact.

Daniel was a doctor who trained through the Austin Hospital after graduating where his passion for urology was ignited. He headed down the surgical pathway completing a Diploma of Surgical Anatomy. This was after studying medicine at Deakin University in Victoria as a postgraduate and after completing prior undergraduate studies. He became an enthusiastic and accomplished researcher culminating in international presentations and recognition well beyond his years. Some highlights included being the youngest elected member of the SIU young innovators committee and his instrumental involvement in setting up the YURO (Young Urology Researchers Organisation) which has seen urology research thrive in this region and globally. His journey in urology although only beginning was off to a flying start- all due to his diligence. The prizes and awards were only just beginning.

Dan rarely stepped aside from a challenge and was always willing to take part in adventures and travels in his personal life. Ironically his death is linked to the things he loved. He was inclusive, engaging and managed to make anyone in contact with him feel that they, and not he, was the centre of the universe. He was such a fun person to be around- laughing, smiling and filling up a room with his genuine love of life.

How do we make sense of such a tragic and unexpected event? The impact circles from those friends and bystanders who desperately tried to save him, his immediate and extended family, his friends, to the numerous colleagues and extended urology and research family he had created over the past years.

At age 33 years, Dan had so much left to give we can only cherish what was shared with us all and celebrate a person who engaged rather than watched- who loved life to the fullest- something to which we can all aspire. Our thoughts are with his parents, brother and sister who ​are undoubtedly proud of Dan- an incredible individual who will never be forgotten.


A/Prof Nathan Lawrentschuk MB BS PhD FRACS (urology)

Associate Editor BJU International; Editor USANZ Supplement, BJU International

Director EJ Whitten Prostate Cancer Centre at Epworth
University of Melbourne
Department of Surgery, Austin Hospital, Olivia Newton-John Cancer Centre and Department of Surgical Oncology, Peter MacCallum Cancer Centre
Melbourne, Australia


November 2018 – about the cover

BJUI November 2018


The article of the month for November 2018 is on work carried out at the University of Pittsburgh Medical Center (UPMC), Pennsylvania, USA: The United States opioid epidemic: a review of the surgeon’s contribution to it and health policy initiatives.

The city is located at the confluence of the rivers Allegheny, Monongahela and Ohio and is known both as the “city of bridges” due to its 446 bridges and the “steel city” as it was formerly home to over 300 steel-related businesses.

The old industrial areas have been restored and redeveloped into museums, heritage centers, parks, libraries and medical centers. UPMC is now one of the biggest employers in Pennsylvania, and has been vital in treating the country’s most recent shooting victims. It has also been a pioneer in transplant surgeries with many world firsts in multiple organ transplants.


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