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

Abstract

PURPOSE\nTo assess the literature around post-treatment asymptomatic residual stone fragments, and to perform a meta-analysis. The main outcomes were intervention rate and disease progression.\n\n\nMATERIALS AND METHODS\nWe searched Ovid Medline, Embase, 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 (shockwave lithotripsy, ureteroscopy or percutaneous nephrolithotomy). Analysis performed using metafor in R and bias using Newcastle-Ottawa scale.\n\n\nRESULTS\nFrom 273 articles, 18 papers (2096 patients) had details of intervention rate for residual fragments. Aggregate intervention rates for ≤4mm fragments rose from 19% (20 months) to 22% (50 months), whilst >4mm fragments rose from 22% to 47%. Aggregate disease progression rates for ≤4mm rose from 25% to 47% and >4mm rose from 26% to 88%. However, there was substantial difference in definition of disease progression. Meta-analysis comparing >4mm against ≤4mm fragments: Intervention rate for >4mm (vs ≤4mm): OR=1.50 (95% CI: 0.70-2.30), p<0.001, I2=67.6%, tau2=0.48, Cochran s Q=11.4 (p=0.02) and Egger s regression: z=3.11, p=0.002. Disease progression rate for >4mm: OR=0.06 (95% CI: -0.98-1.10), p=0.91, I2=53.0%, tau2=0.57, Cochran s Q=7.11 (p=0.07) and Egger s regression: z=-0.75, p=0.45. Bias analysis demonstrated a moderate risk.\n\n\nCONCLUSIONS\nLarger 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.