Surgical Variations in Pediatric Kidney Stone Management: A Discussion on the PKIDS Trial - Gregory Tasian & Nicolas Fernandez

May 29, 2024

Ruchika Talwar hosts a discussion with Greg Tasian and Nicolas Fernandez about surgical variations in managing pediatric kidney stone disease. They discuss the PKIDS study, involving 30 centers, which examines surgical preferences and outcomes for children aged 8-21 undergoing ureteroscopy, shockwave lithotripsy, and percutaneous nephrolithotripsy. Dr. Fernandez highlights the variability in surgical preferences due to factors like stone size and surgeon experience, emphasizing the need for evidence-based guidelines. Dr. Tasian explains the study's patient-centered approach, focusing on quality of life outcomes such as pain interference, anxiety, and sleep disturbance. They emphasize the importance of balancing technological advancements with patient and family experiences to improve care. The discussion underscores the need for better evidence and patient-centered research to guide clinical decisions in pediatric urology.


Gregory E. Tasian, MD, MSc, MSCE, Urologist, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA

Nicolas Fernandez, MD, PhD, Assistant Professor, Pediatric Urologist, University of Washington, Seattle Children’s Hospital, Seattle, WA

Ruchika Talwar, MD, Urologic Oncology Fellow, Department of Urology, Vanderbilt University Medical Center, Nashville, TN

Read the Full Video Transcript

Ruchika Talwar: Hi everyone. Welcome back to UroToday's Health Policy Center of Excellence.

As always, my name is Ruchika Talwar, and today I'm really excited to be joined by two amazing pediatric urologists who will be sharing their work in surgical variations for the operative management of kidney stone disease in children.

First, we have Dr. Greg Tasian from the Children's Hospital of Philadelphia. And next, we have Dr. Nicolas Fernandez from the University of Washington. Thank you both for being here with us today.

Nicolas Fernandez: Thank you so much for the introduction. So as I was saying, thank you so much for the invitation to share our results. This is really a team effort, and thanks to the dedication of some colleagues that are listed here, these are all the co-authors that have participated in this research project.

So the evidence that supports the management of kidney stones in children is really weak; we don't have much research that we can rely on. And the guidelines that support medical management for kidney stones in patients, about eight guidelines that we have available, 50% of them the recommendations are supported by expert opinion alone.

Guidelines determine the management based on stone size as a cut-off value. And the clinical research experience in the adult population uses those thresholds to determine management.

In the Pediatric KIDney Stone Care Improvement Network, also known as PKIDS, 30 centers participated to collaborate and improve patient-centered outcomes. And we prospectively compared the stone management and stone clearance in patient-prioritized experience after treatment with ureteroscopy, shockwave lithotripsy, and percutaneous nephrolithotripsy for patients ranging between eight to 21 years of age.

So the aim of the first phase of the publication that we are presenting today was to report the characteristics of the surgeons and institutions that participated in the PKIDS trial, and determine what factors were associated with their preferences for surgical management. And we hypothesized that there is a wide variation amongst surgeons in their management of pediatric kidney stones.

So for the methods for the study, we basically sent, before the beginning of the trial, a survey to each participating surgeon and institution. And we looked at the outcome measure of strength of preference for alternative surgical treatments for four clinical scenarios that were actually taken from the AUA guidelines. These are listed down below. And that would help us determine what the preferences for surgical management were for those specific clinical scenarios, and that was distributed in the survey as mentioned.

So for example, for patients presenting with two-centimeter kidney stones, we asked the participating surgeons to determine what was their preferred method for treatment between shockwave lithotripsy and PCNL. And we did the same for a scenario with a 1.5-centimeter kidney stone, between ureteroscopy and PCNL, or percutaneous nephrolithotripsy. Same for one-centimeter non-lower pole kidney stone, between ureteroscopy and shockwave lithotripsy. And the last scenario was nine millimeters for proximal ureteral stones, and surgeons had to select between URS and shockwave lithotripsy.

We did collect multiple demographic variables that were also included in the analysis, and the exposures of surgeon and health system characteristics were also recorded in the survey.

So what we found in general was that there was a wide variation in the strength of preferences for each of the alternative treatment options. You can see on the figure on your right side of the screen how, based on each of the four clinical scenarios, there was a distribution of preferred surgical management.

And interestingly, a good example to discuss was the response rate for URS versus PCNL, how the distribution of preference was quite even amongst the surgeons. However, the strength of the preferences was balanced only for the choice that I'm highlighting on the graph, and all the others had a very clear preference for surgical management.

We also identified that there were some clusters of characteristics associated with the variation in their preferences. And as you can see on the figure, this cluster plot was able to discriminate in a way profiles of characteristics that would, in a way, influence the preferred method.

And these were clustered by stone characteristics, patient characteristics, and another one that we determined to be heterogeneous, like value placed by surgeons on the number of anesthesia procedures, for example, that patients would require for the treatment method, radiation exposure, available equipment, and technical experience with managing the equipment.

However, the characteristics that drove those decisions did explain only 30% of the variation in the preference for the type of surgery.

So overall, what we found is that the practice is very heterogeneous, and it's distributed by some specific global clusters that help us understand much better how we should focus our efforts in the future to improve the evidence and influence the management of kidney stone patients in our population.

Ruchika Talwar: Thank you so much for that great overview of your study.

This is a really interesting space, and we look at this space in various disease states. Obviously, we'll discuss urology here, but there's been work looking at clinical variation in prostate cancer, in the management of small renal masses, for example. And it does take a bit of nuance, right, because every situation is different.

But I think that you highlight a really important point, in that a lot of this variation is driven in part by the lack of clear guidelines. And even when we have clear guidelines, sometimes we don't have the evidence. As you alluded to, a lot of the current guidelines for pediatric kidney stone disease rely upon expert opinion.

And so, Dr. Tasian, we'll start with you. I was just wondering if you could give us some background on the PKIDS study, and what evidence gaps you are all looking to fill with this recent work as context.

Gregory Tasian: Ruchika, thanks so much.

The PKIDS Care Improvement Network was really founded to strengthen the evidence base to improve the health of children with kidney stones. And in order to do so, there was a recognition that we needed to generate new knowledge. But not only generate new knowledge, to then apply it into clinical care in order to truly change the way that we practice and to improve the health of patients.

And to start with, we recognized that the original guidelines, which were published in 2016, thankfully for the first time included statements for pediatric patients with stones. And there were eight of those statements, but half of those statements were supported only by expert opinion. So the strength of the evidence that we are using every day to help our patients to care for them surgically really isn't supported by any evidence at all, or very low evidence, at best level B.

So the PKIDS trial was designed to strengthen that evidence base. And to give an understanding just with a single use case, for children who have stones under 20 millimeters, the AUA guidelines recommend with equal weight ureteroscopy or shockwave lithotripsy. Yet within the United States, about 80% to 85% of these children undergo ureteroscopy. Why is there such discordance between an equal weight of guidelines that have very little evidence behind them and the way that we practice surgery?

So we now have those results and we'll be excited to share them at the AUA, but it's really through collaboration and applied outcomes research that we hope to change practice.

Ruchika Talwar: Yeah. Now, Dr. Fernandez, I'm curious, you went through one specific clinical scenario where basically you saw there was no strong preference one way or another with surgical management, yet you showed several other scenarios where there was preference.

Now in that one scenario where you see a lot of variation, I alluded to the fact that variation from a health policy perspective sometimes can indicate inefficiencies or differential outcomes. But pediatric urology I think is different, as I said, from prostate cancer or from the management of small renal masses, for example, specifically pediatric stone disease.

So tell me a little bit about what this observed variation means to you, and how, as a urologic community, we can view these results.

Nicolas Fernandez: Yeah. I think we have had that discussion at multiple opportunities when we meet amongst all the surgeons. And we need to keep in mind that we are at a moment in the management of kidney stones where the technology has allowed us to expand the treatment alternatives that we have for these patients.

And probably a few decades ago we didn't have the technology that we do nowadays, and exploring these questions was not even considered. But nowadays we're now starting to be faced as clinicians with multiple treatment alternatives, but we don't have the evidence to really understand how it is that we should select those treatment options.

And I do struggle most of the time when we're trying to make surgical decisions when I'm discussing with trainees or other surgeons because we use these cut-off values, considering them as the standard rule, but there is no evidence supporting whether a two-centimeter stone is the same for a five-year-old as for a teenager. Just thinking about size and ratios, it doesn't sound like that is totally appropriate.

So I think the importance of this research is trying to balance the new technologies that we have been able to develop, the skill set that surgeons have nowadays, but now use the evidence to better support the management.

And I think one important thing to highlight is that we now have the great advantage of having the input from our patients, because I think we cannot balance our decisions based only on what the best outcome is if we don't take into account that the patient's journey is way different.

So I think finding the balance is what we're aiming to achieve here, and it's just basically the effort of many years of evolution in the management of kidney stones.

Ruchika Talwar: I couldn't agree more. I think you made so many important points there. As we see technologies expand, patients are faced with multiple avenues.

And I think more important than potentially what the outcome is in terms of stone-free rate or re-operation rate really is the patient's experience in this disease state. And more importantly in children, the family's experience. So many other things to consider here.

And Dr. Tasian, if I recall, the quality of life component of this is something that's being measured in the PKIDS study in general. Is that right?

Gregory Tasian: Absolutely. So the trial really started and ended with patients. The idea for the comparisons between all of these surgical modalities was generated from patients' needs.

And that was conceptualized and operationalized through what we call the PKIDS patient and family partners. And this is a group of adolescents who are living with early onset stone disease, as well as caregivers of younger children who have stones. The PKIDS patient and family partners gave rise to the question, but they also gave rise to the outcomes that we measured.

I think as urologists we always think about stone clearance being the one-all, end-all be-all, but it's really not. The outcomes that are meaningful to patients in addition to clearing stones are those things that we as surgeons may not directly think about.

And the ones that were identified and prioritized by our patient family partners were pain interference more than pain intensity. So how does pain interfere with their ability to do their activities of daily living? Anxiety, sleep disturbance, peer relationships, so all of those were selected by our patient family partners.

And then it's identifying how they intersect, either in the same direction or in different directions, with stone clearance. And as the results of the trial were generated, we sat down again with our patient and family partners to help us interpret the results in a way that was meaningful to patients, so that we could report them accurately both in presentation and then in manuscripts.

Ruchika Talwar: Incredible. And I know that this important work is going to guide patient counseling and the management of pediatric kidney stone disease. So really kudos to both of you and to the entire network for all of the work they're doing.

I'm really excited that our UroToday audience has a chance to learn a little bit about this incredible study. And once we have more results available publicly, we'd love to bring you back and do a deeper dive.

Gregory Tasian: We'd be delighted.

Ruchika Talwar: And to our UroToday audience, we really appreciate you tuning in. I know I enjoyed this discussion. We'll see you next time.