Evaluation of “stone free status” in contemporary urologic literature - are we state of the art?

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Background: The success of surgical interventions for ureteral and renal calculi is assessed primarily by stone-free rates. Unfortunately, the definition of success is mired by variability in both the definition of “stone-free” and the imaging modality utilized. It has been demonstrated that the controversially named “clinically insignificant residual fragments” (CIRFS) pose clinically significant symptoms in at least 20% of patients. Furthermore, with its superior sensitivity for detection of stones, non contrast enhanced thin-slice abdominal computed tomography (NCCT) has emerged as the investigation of choice in patients with urinary tract calculi. The continued publication of articles without strict definitions or determination of stone free status prompted us to review the current literature to assess how we evaluate our stone-free outcomes.
Methods:
A literature search on PubMed for surgical management of urolithiasis using MeSH terms for percutaneous nephrolithotomy (PCNL), ureteroscopic lithotripsy, extracorporeal shock wave lithotripsy (ESWL), and laser lithotripsy, published in English between 2004 and 2007 resulted in 143 articles. Case reports, review articles, and studies not including outcomes for these treatment modalities were excluded resulting in 106 articles. Articles were reviewed and evaluated for the treatment modality, definition of stone free status, and the imaging modality employed to determine stone free status.
Results:
Sixty-eight (64%) articles included definition criteria for stone-free status. Definitions varied from no detectable stone in 31 articles to <4mm residual fragments. Detection modalities included ultrasound (4%), plain film radiography (KUB) (26%), intravenous pyelogram (IVP), nephrostogram, noncontrasted thin-slice abdominal CT (2% each), or mixed modalities within an article (60%). Eight articles did not include detection modality.
Conclusions:
More than one-third of articles evaluating surgical management of urinary calculi do not specifically address definitions of stone-free status. Although NCCT is frequently used for the initial diagnosis of urinary calculi and is the most accurate imaging method to determine stone-free status, it is rarely used exclusively to assess outcomes in contemporary urologic literature. Although concerns regarding health care expenditures and radiation exposure may legitimately limit routine clinical postoperative use of NCCT, these factors must be considered when critically reviewing published results of stone management.

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