Preliminary results of a randomized controlled trial of prophylactic shock wave lithotripsy for small asymptomatic renal calyceal stones.

OBJECTIVE

To report a prospective, randomized study to determine whether prophylactic extracorporeal shockwave lithotripsy (ESWL) is justified as a treatment for small, asymptomatic calyceal stones.

PATIENTS AND METHODS

The study included 228 patients with small (< 15 mm total diameter) asymptomatic calyceal stones; 113 patients were randomized to undergo ESWL and 115 to the control group who were kept under observation. Outcome measurements included the stone-free rate, requirement for additional treatment, symptoms, quality of life and renal function.

RESULTS

In all, 200 patients had at least one annual follow-up; all outcome measurements reported were those at the most recent follow-up (mean 2.2 years, range 1-5). In the ESWL group 28 patients (28%) were stone-free, compared with 16 (17%) in the observation group (odds ratio 1.95, 95% confidence interval, CI, 0.97-3.89, P = 0.06). Additional treatment in the form of analgesics, antibiotics, ESWL, stent insertion and ureteroscopy, was required in 21 (21%) patients in the observation group and 15 (15%) in the ESWL group (odds ratio 0.66, 95% CI 0.32-1.37, P = 0.27). Ten patients in the observation group required invasive procedures, vs none in the ESWL group. There was no evidence of differences in the symptoms, quality of life or renal function tests between the arms of the trial at the final follow-up.

CONCLUSIONS

Prophylactic ESWL for small asymptomatic renal calyceal stones does not appear to offer any advantage to patients in terms of stone-free rate, quality of life, renal function, symptoms or hospital admissions. However, a policy of observation is associated with a greater risk of requiring more invasive procedures. A longer follow-up is required to assess the validity of these preliminary findings.