El-Assmy A et al, 2016: Does lithotripsy increase stone recurrence? A comparative study between extracorporeal shockwave lithotripsy and non-fragmenting percutaneous nephrolithotomy.
El-Assmy A, Harraz AM, Eldemerdash Y, Elkhamesy M, El-Nahas AR, Elshal AM, Sheir KZ.
Department of Urology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt.
OBJECTIVES: 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.
PATIENTS AND 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.
Arab J Urol. 2016 Apr 3;14(2):108-14. doi: 10.1016/j.aju.2016.02.004. eCollection 2016 Jun. FREE ARTICLE
Fresh data on a non-remarkable recurrence rate after ESWL compared to PNL. Why a stone size > 8 mm should be a (physiological) threshold value is difficult to understand with a mean (SD) stone size of 13.8 mm (6) in the ESWL and 9.4 mm (1.3) in the PNL group.
The recurrence rate after 10 years is high although the absolute numbers are very small. In addition the high drop-out rate may cause a bias with selection of symptomatic patients. Unfortunately there is no information if the recurrences were symptomatic or not and what kind of therapy became necessary.
The “shift from baseline stone location, with an increased tendency for most new stones to recur in the calyces as opposed to the pelvis” has a physiological explanation: At least most of the calcium containing stones start their growth affixed to a papilla; when they dislodge and pass into the renal pelvis were they grow to a larger size they become symptomatic