title: Does lithotripsy increase stone recurrence? A comparative study between extracorporeal shockwave lithotripsy and non-fragmenting percutaneous nephrolithotomy.
abstract: OBJECTIVE
  To investigate the effect of stone fragmentation on late stone recurrence by comparing the outcome of extracorporeal shockwave lithotripsy (ESWL) and non-fragmenting percutaneous nephrolithotomy (PCNL), and to investigate factors contributing to recurrent calculi.
  
  
  METHODS
  We evaluated stone recurrence in 647 patients who initially achieved a stone-free status after ESWL and compared the outcomes to 137 stone-free patients treated with PCNL without stone fragmentation. Patients were evaluated every 3 months during the first year and every 6 months thereafter to censorship or time of first new stone formation. Stone recurrence rates were calculated using the Kaplan-Meier method. The effects of demographics, stone characteristics, and intervention on the recurrence rate were studied using the log-rank test and the Cox-regression analysis.
  
  
  RESULTS
  For ESWL the recurrence rates were 0.8%, 35.8% and 60.1% after 1, 5 and 10 years, which were comparable to the 1.5%, 35.5% and 74.9%, respectively found in the PCNL group (P = 0.57). Stone burden (>8 mm) and a previous history of stone disease were significantly associated with higher recurrence rates regardless of the method of stone intervention (P = 0.02 and P = 0.01, respectively). In the ESWL group, a stone length of >8 mm showed a higher recurrence rate (P = 0.007). In both the ESWL and PCNL groups, there was a significant shift from baseline stone location, with an increased tendency for most new stones to recur in the calyces as opposed to the pelvis.
  
  
  CONCLUSIONS
  In comparison with PCNL, ESWL does not increase long-term stone recurrence in patients who become stone-free. The stone burden appears to be the primary factor in predicting stone recurrence after ESWL.
authors.affiliation: Department of Urology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt.
authors.forename: Ahmed
authors.initials: A
authors.lastname: El-Assmy
authors.affiliation: Department of Urology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Harraz
authors.affiliation: Department of Urology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt.
authors.forename: Yasser
authors.initials: Y
authors.lastname: Eldemerdash
authors.affiliation: Department of Urology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Elkhamesy
authors.affiliation: Department of Urology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt.
authors.forename: Ahmed R
authors.initials: AR
authors.lastname: El-Nahas
authors.affiliation: Department of Urology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Elshal
authors.affiliation: Department of Urology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt.
authors.forename: Khaled Z
authors.initials: KZ
authors.lastname: Sheir
keywords: ESWL, extracorporeal shockwave lithotripsy; Extracorporeal shockwave lithotripsy; Fragmentation; HR, hazards ratio; KUB, plain abdominal radiograph of the kidneys, ureters and bladder; NCCT, non-contrast CT; OSS, open stone surgery; PCNL, percutaneous nephrolithotomy; Percutaneous nephrolithotomy; Stone recurrence; US, ultrasonography