Results from Largest CHOP-led Pediatric Kidney Stone Study Build Critical Evidence Base

Results from the PKIDS Network contributed to one of the largest studies for the surgical management of kidney stones patient outcomes of three approaches.

Research results from the Pediatric KIDney Stone (PKIDS) Care Improvement Network, led by Children's Hospital of Philadelphia, are helping to close an urgent, unmet gap in knowledge by providing strong scientific evidence for treating a rapidly growing population of children and adolescents with kidney stones.

Principal investigator and Director of the PKIDS Network, Gregory Tasian, MD, MSc, MSCE, and his colleagues, including Jonathan Ellison, MD, Associate Director of the PKIDS Network and a pediatric urologist at Children's Wisconsin, compared the clinical outcomes and post-surgery impact on patients' lives of three approaches to kidney stone removal: ureteroscopy, an endoscopic outpatient procedure; shockwave lithotripsy, a noninvasive outpatient procedure; and percutaneous nephrolithotomy (PCNL), a minimally invasive surgery with a short hospital stay.

"The idea for the trial arose from our patient and family partners within PKIDS," said Dr. Tasian. "They had each confronted a lack of information when they were making decisions about the right surgical option for themselves or their child."

Kidney stones occur when certain minerals in urine stick together and form hard deposits. Professional organizations such as the American Urological Association and European Association of Urology have put forth guidelines to treat kidney stones largely based on adult studies and expert opinion that recommend shockwave lithotripsy as equally as ureteroscopy.

Dr. Tasian noted that approximately 70-80% of children in the United States who require surgery for kidney stones undergo ureteroscopy.

"There's this imbalance between what's recommended and what's actually done," he said. "That's where this trial comes in. Both approaches remove stones equally well, but there is a difference in the experience of those children after surgery."

Shockwave Lithotripsy vs. Ureteroscopy

One study enrolled 1,142 patients ages 8 to 21 with kidney and/or ureteral stones between 2020 and 2023 at any of the 31 sites in the PKIDS Network. The primary outcome was stone clearance, which researchers evaluated using ultrasound on the operated kidney around six weeks after surgery. The secondary outcome included patient-reported outcomes collected one, three, six, and 12 weeks after surgery. Via questionnaire, patients reported on pain intensity, pain that disrupted their daily functioning, anxiety, psychological stress, sleep disturbance, peer relationships, and urinary symptoms.

A minimally invasive procedure, a ureteroscopy involves passing a scope through the urethra to the bladder and kidneys to find stones and break them up with a laser. In shockwave lithotripsy, doctors identify stones through ultrasound or X-ray, then send high-energy pulses through the patient's skin to make the stones small enough to pass in the urine.

In the study, 79% of patients who underwent ureteroscopy received a stent, which is a thin tube inserted into the ureter to help urine flow, compared to the 3% who underwent shockwave lithotripsy. Notably, researchers found that 10 times more patients receiving ureteroscopy required a second procedure under general anesthesia to remove the ureteral stent.

Researchers did not detect clinically meaningful differences in stone clearance between ureteroscopy and shockwave lithotripsy, though more patients in the ureteroscopy group had repeat surgery to clear stones. Shockwave lithotripsy was associated with less pain and lower urinary symptoms during the first week after surgery. These patients also missed less school, and their caregivers missed less work than those having ureteroscopy.

Percutaneous Nephrolithotomy vs. Ureteroscopy

The other CHOP-led study drew on Dr. Ellison's expertise in PCNL, in which a doctor removes stones using a scope placed into the kidney through a small incision in the patient's back. Based only on expert opinion, guidelines for surgical management of kidney stones larger than 20 mm suggest either PCNL or shockwave lithotripsy, with no mention of ureteroscopy. Dr. Ellison and his team compared PCNL with ureteroscopy to determine which method cleared stones more effectively, and which had fewer negative impacts on patients' recovery.

Researchers enrolled 1,039 patients ages 8 to 21 across all 31 sites in the PKIDS Network. Of that group, 36 patients received PCNL, and 43 patients received ureteroscopy for stones larger than 15 mm. Stone clearance, assessed by ultrasonography several weeks after surgery for both approaches, demonstrated no statistically significant difference for either approach. However, for stones larger than 15 mm, PCNL showed better stone clearance in patients than ureteroscopy.

To evaluate patients' experiences with pain and symptoms that affected their physical, social, and emotional well-being, patients filled out questionnaires one, three, six, and 12 weeks after surgery. Questionnaire scores revealed that patients who underwent PCNL experienced significantly less postoperative pain intensity, psychological stress, and sleep disturbances, among other factors, than those who underwent ureteroscopy.

"We believe that these results will influence guideline creation and surgical care patterns, ultimately resulting in better surgical and patient-reported outcomes for children with kidney stone disease," Dr. Ellison said.

Patient-driven Outcomes

Studies evaluating the social, emotional, and physical impacts of these surgeries on the lives of children and adolescents have not previously existed. With these findings, Dr. Tasian and his colleagues aim to enhance pediatric patient and caregiver decision-making for kidney stone surgeries while equipping clinicians with knowledge of techniques that will help keep the patient experience at the forefront.

"Within PKIDS, we think about research as a cycle rather than a linear process," Dr. Tasian said. "Now that we have this information, we need to make it available to clinicians who are performing the surgery, to urologists, to families, and to adolescents and young adults so that they are informed about the choices and the expectations that they should have after surgery."

Drs. Tasian and Ellison will be hosting webinars and inviting the study participants to see what they have learned. They plan to engage the PKIDS community to understand how best to disseminate this knowledge, both to patients and families, and to clinicians, to begin to incorporate their findings into clinical care.

"Our findings provide information that allow for tailored approaches to kidney stone treatment for children and their families," Dr. Tasian said. "Although future clinical trials are important, we hope that clinical practice guidelines will consider outcomes that matter to patients."

The PKIDS Network has expanded over the last five years to include 31 sites across the United States and Canada. The trial's findings were published as two studies in JAMA Network Open.

Dr. Tasian's study was supported through a Patient-Centered Outcomes Research Institute Program Award (CER-2018C3-14778).