Randy Dotinga is a medical writer based in San Diego, Calif.

Randy Dotinga

A new study suggests that metallic Resonance ureteral stents are a good option for management of malignant ureteral obstruction because they promote strong long-term outcomes.

	The stents offer "excellent treatment outcomes and improved cost effectiveness," said study co-author Philippe E Spiess, MD, MS, of Moffitt Cancer Center and the University of South Florida, Tampa.

	According to Dr. Spiess, metallic ureteral stents offer an alternative to traditional polymer stents and require annual exchanges instead of once every 3-4 months.

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	"Over recent years, several retrospective studies have been performed to validate their efficacy and longevity in the setting of malignant ureteral obstructions of various genitourinary and non-genitourinary etiologies," he said. "However, there is limited data on their long-term viability and outcomes."

	Only one kind of metallic ureteral stent-the Resonance-is available for use in the U.S., said study co-author Timothy Juwono, MD, of the University of South Florida Morsani College of Medicine.

	For the new single-center study, which was presented at the 2017 American College of Surgeons Clinical Congress in San Diego, the authors tracked 148 metallic Resonance ureteral stents that were placed in 80 cases of malignant ureteral obstruction from 2009-2016.

	"Our patients were managed with Resonance metallic ureteral stent for a range of between 24-83 months with a median of five stent exchanges during the study duration. The median stent life was 10 months, which is 6-7 months longer than the traditional polymer stent," Dr. Juwono said.

	The success rate was 85.1% for stents that were successfully placed in patients who didn't die or become lost to follow-up.

	"These patients were excluded since meaningful data, meaning stent success or failure, could not be determined," Dr. Juwono said.

	The stent failure rate was reported at 9.6%, "which is well below that reported of polymer stents," Dr. Juwono added. "Malignant ureteral obstruction is a difficult condition to manage, with reported failure rates of up to 40%-50% with polymer stents reported with refractory malignant obstruction and in the long-term setting. Our data indicates that Resonance metallic ureteral stents are, in fact, more effective and resistant to ureteral compression provided they are used in the right clinic setting; ie, malignant ureteral obstruction."

	Another 5.3% of stents had to be removed due to intolerability (flank pain, hematuria, and/or urinary frequency) within 2 months of placement.

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	Study co-author Adam Baumgarten, MD, of the University of South Florida Morsani College of Medicine, described the study findings this way: "No stent is able to stay indwelling lifelong, but this study shows that most placed metallic ureteral stents are capable of staying indwelling for their indicated duration, which saves the patient frequent minor surgical procedures with their inherent risk and cost."

	"In our prior study, we actually calculated the total cost-OR time, anesthesia, equipment, and the cost of the stent-of using metallic stents and compared it to polymer stents," Dr. Spiess said.

	As reported in the 2014 study, the authors found that the annual estimated cost for polymer stents exchanged every 90 days ranged from $9,648-$13,128 but dropped to $4,211-$5,313 for those exchanged a median of every 288 days 

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Metallic stents efficacious for malignant ureteral obstruction

In another potential sign of racial disparities in urologic care, a new study finds that urologic restoration surgery is significantly less likely to be used to treat African-American men with stress urinary incontinence (SUI) than Caucasian men, although African-Americans appear to have higher rates of SUI.

	"There is an imbalance in racial composition between the two groups, and the imbalance is opposite from what you would expect based on data regarding prevalence of the conditions," said Kara E. McAbee, MD, a urology resident at Wake Forest Baptist Health, who spoke in an interview with 

	Dr. McAbee is first author of the study, which was presented at the 2017 American College of Surgeons clinical congress in San Diego. She worked on the study with Ryan Terlecki, MD, and colleagues.

In 2006, a study reported that 21% of African-American men surveyed reported urinary incontinence over the past year, the highest of any ethnic group. The overall prevalence in men was 17% 

	Urologist Charles Modlin, MD, MBA, who is familiar with the study findings, said in an interview that African-American men may have higher rates of SUI because of delayed presentation to physicians.

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	In part due to lack of health insurance, they "are less commonly referred by primary care doctors to urologists for treatment of benign prostate disease and even for screening for prostate cancer and therefore often present to urologists with advanced prostate cancer compared to their white male counterparts," said Dr. Modlin, who studies racial disparities in urology. He is founder and director of the Cleveland Clinic Minority Men’s Health Center.

	For the new study, the authors analyzed a prospectively collected single-surgeon database for the years 2011-2016.

	"We wanted to determine if the racial composition of men receiving prosthetic surgery for ED was different from that of our population undergoing surgical correction of SUI," Dr. McAbee said.

	The authors found a difference in the racial makeup of the cases: Of the 247 inflatable penile prosthesis cases, 77.7% were Caucasian, 19.0% African-American, and 2.8% other. Among the 110 artificial urinary sphincter and male sling cases, 87.2% were Caucasian, 9% African-American, and 3.6% other.

	The etitologies for the inflatable penile prosthesis cases were prior prostatectomy (34.4%) and benign disease (65.6%). For the other cases, the etitologies were cancer (95%) and benign disease (5%).

	The authors found that African-Americans were significantly less likely to receive surgical restoration for SUI compared to erectile dysfunction 

	The authors also discovered that 82.5% of all urologic prosthetic surgery in African-American men was for erectile dysfunction compared to 66.7% in Caucasian men, "which makes sense given both prostate cancer and ED are more common in African-American males," Dr. McAbee said.

	"There may be racial differences in the degree of bother of symptoms of erectile dysfunction versus incontinence," Dr. McAbee said. "Within different populations, there also may be a difference of knowledge of procedures available for the correction of erectile dysfunction or incontinence."

	Other possible reasons for the discrepancy include "access to care, payer difference, referral patterns, surgeon race, surgeon communication skills, and comorbidities preventing elective surgery," Dr. McAbee said.

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	Dr. Modlin pointed to the possibility of "unconscious/implicit bias or unequal treatment on the part of the health provider." Also, he said, African-American males "may be offered more medical treatments rather than offered options for surgical treatment. Additionally, they may themselves be more likely to not select surgical SUI treatment."

	What now? "We need to be aware that disparities in delivery of urologic care exist," Dr. McAbee said, "and we must actively work to eliminate them through collaboration with other providers, better patient education, and community outreach."

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In another potential sign of racial disparities in urologic care, a new study finds that urologic restoration surgery is significantly less likely to be used to treat African-American men with stress urinary incontinence than Caucasian men, although African-Americans appear to have higher rates of SUI.

Racial disparity seen with SUI surgical restoration

	A large new study provides more evidence that cholesterol drugs may lower kidney stone formation. Researchers found that subjects who took statins were less likely to develop stones, and they spotted an especially dramatic effect among recurrent stone formers.

	The findings don’t say anything about a direct link between statins and stone formation, so there’s no way to know if cholesterol drugs hold value as a preventive measure for patients at risk of stones. “For now, patients with stones who are already on statins should be encouraged to continue use,” said lead author Andrew Cohen, MD, a urology resident at the University of Chicago Medical Center.

	At issue: Are statins beneficial for those at risk of stones? There’s sparse research into the question.

	A 2013 study of military medical records 

 2013; 79:351-5) found fewer cases of stone formation in patients who took statin medications compared to those who did not (3.1% vs. 3.7%, univariate OR=0.83, 95% CI: 0.76-0.91, 

<.001), and multivariate analysis suggested a protective effect for statins (OR=0.51, 95% CI: 0.46-0.57, 

 2015; 43: 49–53) of more than 52,000 subjects linked dyslipidemia to a higher rate of kidney stones in both univariate (HR=2.2 [CI: 1.9–2.5; 

<.001]) and multivariate (HR=1.2 [CI: 1.0–1.5; 

Persistent decline in renal function seen after first stone case

	For the current study, presented at the 2016 AUA annual meeting in San Diego, the authors identified 101,259 patients diagnosed with hyperlipidemia during enrollment at the University of Chicago Medical Center from 2009-2011. Researchers tracked the subjects for stone formation and cholesterol drug use through 2015.

	Almost 48% received a prescription for a statin in the study period; they were much older (60.7 vs. 51.9 years) and more obese (29.2 kg/m

	Those who took statins and hadn’t had stones previously were less likely than non-users to develop new stones (3.8% vs. 4.7%, 

	After adjusting for race, body mass index, gender, and comorbidities, the authors found evidence of a protective effect of statins (OR=0.57, 

<.01), and the apparent effect was greatest in previous stone formers (OR=0.53, 

Next: No link between cholesterol level, stone risk

No link between cholesterol level, stone risk

	Is lower cholesterol translating to fewer stones? Dr. Cohen doesn’t think so.

	“Our inclusion of lipid lab data suggests patients prescribed statins were compliant with their medication. But there was no clinically significant association between high total cholesterol or high LDL cholesterol levels and stone risk. This may mean statins function via reducing inflammation and not by direct lipid-lowering effects,” said Dr. Cohen, who worked on the study with Sangtae Park, MD, MPH, and colleagues.

	“Statin-treated rats have been shown to have lower levels of renal tubular cell injury and increased antioxidants, but more research is needed to understand the biology of this association. Statins may have wide-reaching effects within the body that are not completely understood,” Dr. Cohen said.

	“Future study involving concurrent 24-hour urine parameters and stone analysis for those patients on statin therapy may be of benefit,” Dr. Cohen said. “Furthermore, if an anti-inflammatory effect is truly the cause, the utility of other anti-inflammatory medications could be studied in this context. A prospective randomized clinical trial would be definitive.”

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A large new study provides more evidence that cholesterol drugs may lower kidney stone formation.

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	The emergence of robot-assisted laparoscopic donor nephrectomy (RLDN) and new findings regarding renal transplant patients' cancer risk highlight the discussions of transplantation/vascular surgery discussions at this year's AUA meeting.  The transplantation/vascular surgery take-home messages were presented by Christopher L. Marsh, MD of Scripps Center for Organ Transplantation, La Jolla, CA.

Robot-assisted laparoscopic donor nephrectomy (RLDN) is beginning to be rolled out, but long-term data are needed to confirm its feasibility. Compared to standard laparoscopic donor nephrectomy, RLDN required longer operation time and warm ischemia time but had shorter hospital stays. Complication rates were similar.

Kidney transplant recipients show higher risk of cancers such as kidney and bladder cancer.

Transvaginal natural orifice transluminal endoscopic surgery-assisted living donor nephrectomy is a feasible and reproducible alternative to laparoscopic live donor nephrectomy in select cases. The approaches were similar in cold/hot ischemia time, operation time, and length of stay. 

Kidneys from older donors (>70 years of age) appear to be feasible for transplantation. Age of donor did not affect graft loss. In donations from donors under age 70 years, average serum creatinine was significantly lower up until 36 months. Cumulative graft survival at 1, 3, and 4 years was lower for kidneys from older donors.

Renal transplant recipients who required percutaneous nephrostomy had similar graft survival as the general transplant population (11.9 vs. 10.5 years). At 63%, distal ureteral stricture was the most common indication.

Robot-assisted re-do ureteroneocystostomy can be performed with acceptable results (despite lengthy operative time) and is linked to early recovery, with all patients discharged on the first day with Foley catheter for 1 week.

Continue to the next page for more take-home messages

		Cystoscopy with bladder washout with 6 liters of saline appears to be an effective method to decrease frequency of urinary tract infections in renal transplant recipients.

		To reduce postoperative lymphoceles in renal transplants, two easy strategies-placement of a retroperitoneal drain and FloSeal hemostatic matrix-both show promise.

		A literature review identified 56 studies exploring small renal masses in transplant allograft kidneys and showed that the current management of small renal masses in transplant kidney tumors mirrors management of renal masses in the average population.

		Patients with nonmuscle-invasive bladder cancer after renal transplantation could be treated with mitomycin C or bacillus Calmette-Guérin (BCG) vaccine depending on risk level. Adjuvant BCG reduced risk as did change to mTOR inhibitors, while having multiple tumors increased risk. For muscle-invasive bladder cancer, radical cystectomy with ileal conduit is the treatment of choice.

		Renal transplants may benefit from monitoring of insertion-deletion allele polymorphism, N-glycans hybrid m/z 2033, and major proteins mediating HIF-1 signaling.

		In several separate animal models of kidney transplantation, researchers found various protective results in infusion with carbon monoxide releasing molecule, sildenafil (Viagra), and tricostatin A.

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The emergence of robot-assisted laparoscopic donor nephrectomy (RLDN) and new findings regarding renal transplant patients' cancer risk highlight the discussions of transplantation/vascular surgery discussions at this year's AUA meeting.

Randy Dotinga

Articles

Metallic stents efficacious for malignant ureteral obstruction

Racial disparity seen with SUI surgical restoration

Study: Statin users less likely to develop kidney stones

Transplantation/Vascular Surgery: Emergence of robotic donor nephrectomy