Natural History of Post-Treatment Kidney Stone Fragments: A Systematic Review and Meta-Analysis

Abstract

Purpose: We assessed the literature around post-treatment asymptomatic residual stone fragments and performed a meta-analysis. The main outcomes were intervention rate and disease progression. Materials and Methods: We searched OvidÒ, MEDLINEÒ, EmbaseÔ, the Cochrane Library and ClinicalTrials.gov using search terms: "asymptomatic", "nephrolithiasis", "ESWL", "PCNL", "URS" and "intervention." Inclusion criteria were all studies with residual renal fragments following treatment (shock wave lithotripsy, ureteroscopy or percutaneous nephrolithotomy). Analysis was performed using 'metafor' in R and bias determined using NewcastleeOttawa scale. Results: From 273 articles, 18 papers (2,096 patients) had details of intervention rate for residual fragments. Aggregate intervention rates for 4 mm fragments rose from 19% (20 months) to 22% (50 months), while >4 mm fragments rose from 22% to 47%. Aggregate disease progression rates for 4 mm rose from 25% to 47% and >4 mm rose from 26% to 88%. However, there was substantial difference in definition of "disease progression." Meta-analysis comparing >4 mm against 4 mm fragments: intervention rate for >4 mm (vs 4 mm): OR[1.50 (95% CI 0.70e2.30), p <0.001, I 2 [67.6%, tau 2 [0.48, Cochran's Q [11.4 (p[0.02) and Egger's regression: z[3.11, p[0.002. Disease progression rate for >4 mm: OR[0.06 (95% CI À0.98e1.10), p[0.91, I 2 [53.0%, tau 2 [0.57, Cochran's Q[7.11 (p[0.07) and Egger's regression: z[À0.75, p[0.45. Bias analysis demonstrated a moderate risk. Conclusions: Larger post-treatment residual fragments are significantly more likely to require further intervention especially in the long term. Smaller fragments, although less likely to require further intervention, still carry that risk. Notably, there is no significant difference in disease progression between fragment sizes. Patients with residual fragments should be appropriately counselled and informed decision-making regarding further management should be done.

Optimal Delivery of Follow-Up Care for the Prevention of Stone Recurrence in Urolithiasis Patients: Improving Outcomes

“… 56 In a recent meta-analysis, Brain et al evaluated literature regarding natural history of post-treatment renal stone fragments and concluded that patients with residuals >4 mm carry a significantly increased risk of intervention compared to fragments ≤4 mm. 57 Disease progression did not differ significantly between the two groups. 57 The EAU Guideline Urolithiasis Panel performed a systematic appraisal of the literature, concluding that for residuals ≤4 mm intervention was in the range 17–29%, disease progression 9–34% and spontaneous expulsion 21–34% during 4 years of follow-up, while for fragments >4 mm, intervention was in the range 24–100%.…”

“… 57 Disease progression did not differ significantly between the two groups. 57 The EAU Guideline Urolithiasis Panel performed a systematic appraisal of the literature, concluding that for residuals ≤4 mm intervention was in the range 17–29%, disease progression 9–34% and spontaneous expulsion 21–34% during 4 years of follow-up, while for fragments >4 mm, intervention was in the range 24–100%. 58 Raman et al evaluated patients with residuals after percutaneous nephrolithotomy (PNL) and found that patients with fragments 2–4 mm experienced more symptomatic episodes and re-interventions compared to those with fragments <2 mm.…”

Use of Internally Validated Machine and Deep Learning Models to Predict Outcomes of Percutaneous Nephrolithotomy using data from the BAUS PCNL audit

“…However, more recently, this has been challenged. These residual fragments are likely to become clinically significant [27], and therefore the definition of ‘stone free’ has been redefined to ‘no fragments’. This ambiguity about stone free ascertainment and definition are the likely reasons behind poor prediction.…”

Risk Factors Associated With The Adverse Outcome Of Residual Stones After PCNL For Upper Urinary Tract Calculi

“…However, the latest studies show that in some patients, postoperative small residual stones fragments are not expelled and may lead to stone-related symptoms such as infection, hematuria, back pain, and even require surgical treatment [5][6][7][8]. In addition, the probability of stone growth in patients with upper urinary tract stones after surgery is 10% within 1 year, 35% within 5 years, and up to 50% within 10 years [9,10].…”