Over the long term, stone recurrence is less frequent with percutaneous nephrolithotomy (PCNL) than with shock wave lithotripsy (SWL).
The 19-year study, presented by first author Amy E. Krambeck, MD, a Mayo Clinic urology resident, found that 40% of patients undergoing PCNL experienced stone recurrence compared to 53.5% of those treated by SWL.
"We are finding out that the type of treatment for stone disease can have long-term effects. We have records going back 20 years, and this offered us a unique opportunity to look at the treatment modalities. This study shows percutaneous treatment to be safe," Dr. Krambeck told Urology Times.
Accounting for pain
"Our number-one complication was pain," Dr. Krambeck said. "That had a lot to do with the large nephrostomy tubes that were being used during the early years of the procedure. The technology has changed dramatically. The tube size has decreased. Access sheaths limit the absorption of fluids and the instruments used to break up the stones have advanced, as well. I don't think pain would be as frequent today."
The authors noted that the PCNL group had a higher body mass index at both presentation and follow-up than the other two groups did. In the 87 patients treated with PCNL, 35.6% were obese and 24.7% had hypertension as pre-existing conditions.
"This is just a theory, but I think that large people are more likely to have worse stone disease. There is a metabolic syndrome associated with stone disease that includes obesity, hypertension, and diabetes," Dr. Krambeck said.
New-onset renal insufficiency was reported in nine PCNL patients (10.6%); hypertension, in 29 (34%); diabetes mellitus, in 23 (23.5%); and ureteropelvic junction obstruction, in three (3.5%). The PCNL group appeared to have a higher incidence of diabetes than the control group did, but Dr. Krambeck noted that multivariate analysis eliminated the relationship between diabetes and PCNL when the researchers controlled for patient size and weight.
"The percutaneous patients tended to have higher BMIs, and it is this weight that is associated with diabetes," she said.
A companion study of the SWL patients, also presented at the meeting, found that obesity, male gender, complicated SWL, and treatment of lower pole stones appeared to predispose these patients to stone recurrence (see, "Stone recurrence, complications common after SWL"). Of the 288 patients in this cohort, 50 presented with one recurrence, 78 with two to five recurrences, 18 with six to nine recurrences, and eight had 10 or more recurrences. Recurrent disease was not associated with the development of new-onset hypertension (p=.354) or renal insufficiency (p=.154); however, recurrence was associated with the development of new-onset diabetes (p=.20).
"The take-home message is that percutaneous nephrolithotomy is safe. It is associated with acute complications, but over the long term, it is a good treatment for stone disease," Dr. Krambeck concluded.