Quantification of Asymptomatic Kidney Stone Burden by Computed Tomography for Predicting Future Symptomatic Stone Events

Abstract

Objective To find the optimal characterization of asymptomatic radiographic stone burden on computed tomographic (CT) scans. Methods A survey was sent to stone formers who underwent a CT scan while asymptomatic during a stone clinic evaluation. Symptomatic stone passage events after CT scan were detected by survey and medical record review. Radiographic stone burden was quantified by number of stones, largest stone diameter, automated total stone volume (TSV), and bilateral stones and then compared as predictors of stone events. Results There were 550 stone formers; 43% had a stone event a median 4.7 years after the CT scan. Stone burden by quartiles was 0–1, 2–3, 4–6, ≥7 for number of stones; 0–2, 3–4, 5–7, ≥8 mm for largest stone diameter; and 0–8, 9–78, 79–280, and ≥ 281 mm3 for TSV; 48% had bilateral stones. The hazard ratios (HRs) for symptomatic event was 1.30 (p<0.001) for the number of stones per quartile, 1.26 (p<0.001) for largest stone diameter per quartile, 1.38 (p<0.001) for TSV per quartile, and 1.80 (p<0.001) for bilateral stones. On multivariable analysis, only TSV was an independent predictor of symptomatic events (HR=1.35 per quartile, p=0.01). This risk of events with TSV was also independent of demographics, urine chemistries, and stone composition. Among the 53 patients with interim events between CT scans, a rapid increase in TSV between CT scans (>570 mm3/year) predicted subsequent events (HR=2.8, p=0.05). Conclusions Automated TSV is more predictive of symptomatic events than manual methods for quantifying stone burden on CT scan.

Stone Composition Among First-Time Symptomatic Kidney Stone Formers in the Community

“…Cystine stones have a high rate of recurrence due to genetic cystinuria. 33,34 Consistent with their high recurrence rates, uric acid, struvite, brushite, and cystine stones became progressively more common among stone formers with each subsequent stone composition analysis.…”

The Urological Association of Asia clinical guideline for urinary stone disease

“…A prior retrospective cohort study showed that 31.8% of asymptomatic stone patients developed symptomatic stone events in 31.6 months of mean study follow up . Recent cohort studies reported that the development of symptomatic stone events were 53.6% for 31 months of mean follow up and 42% for 4.7 years of median follow up, respectively . Studies suggested that larger stone size, in particular volume, and rapid increase in stone volume appeared to be predictive of future stone events in patients with asymptomatic stones Some RCTs reported that observation of asymptomatic renal stone did not affect the patient's follow up compared with SWL or PCNL A patient decision‐based survey showed that 22.8% chose observation, which revealed that the patients who had passed larger stones were less likely to choose observation over surgery …”

“…224 Recent cohort studies reported that the development of symptomatic stone events were 53.6% for 31 months of mean follow up and 42% for 4.7 years of median follow up, respectively. 225,226 Studies suggested that larger stone size, in particular volume, and rapid increase in stone volume appeared to be predictive of future stone events in patients with asymptomatic stones (LE:4). 227,228 Some RCTs reported that observation of asymptomatic renal stone did not affect the patient's follow up compared with SWL or PCNL (LE:2).…”

Threshold Point of the Total Stone Volume Matter on Decision of Flexible Ureteroscopy

“…12 Another study indicated that SWL is an effective treatment for 360 mm 3 volume kidney stones. 30 The risk of future symptomatic events increase the size of the asymptomatic kidney stone (79 mm 3 -280 mm 3 ) was reported by Selby et al 13 Our study is naturally retrospective and enrolled relatively small patient number but has a several strengths points. Cut off volume measurement has not been reported yet to decide either FURS or PNL and it demonstrates strong relation with the outcomes.…”

“…10,11 Against this background; stone length in the evaluation of renal calculi is accustomed mistake and stone volume is a more powerful predictor for the approach stone treatment and follow-up. [12][13][14][15] We aimed to define the real cut-off value for the determination of appropriate treatment modality which gives us higher success rate, lower morbidity and cost.…”