Endoscopic Combined Intrarenal Surgery Versus Percutaneous Nephrolithotomy for Large and Complex Renal Stone: A Systematic Review and Meta-Analysis

Kidney stone disease is a crystal concretion formed usually within the kidneys. It is an increasing urological disorder of human health, affecting about 12% of the world population. It has been associated with an increased risk of end-stage renal failure. The etiology of kidney stone is multifactorial. The most common type of kidney stone is calcium oxalate formed at Randall's plaque on the renal papillary surfaces. The mechanism of stone formation is a complex process which results from several physicochemical events including supersaturation, nucleation, growth, aggregation, and retention of urinary stone constituents within tubular cells. These steps are modulated by an imbalance between factors that promote or inhibit urinary crystallization. It is also noted that cellular injury promotes retention of particles on renal papillary surfaces. The exposure of renal epithelial cells to oxalate causes a signaling cascade which leads to apoptosis by p38 mitogen-activated protein kinase pathways. Currently, there is no satisfactory drug to cure and/or prevent kidney stone recurrences. Thus, further understanding of the pathophysiology of kidney stone formation is a research area to manage urolithiasis using new drugs. Therefore, this review has intended to provide a compiled up-to-date information on kidney stone etiology, pathogenesis, and prevention approaches.

Rationale and objectives: Kidney stones have been associated with an increased risk of ESRD. However, it is unclear if there is also an increased risk of mortality and if these risks are uniform across clinically distinct categories of stone formers. Study Design: Historical matched cohort study Setting and Participants: Stone formers in Olmsted County, Minnesota, between 1984 and 2012 identified using ICD-9 codes. Age and gender-matched individuals who had no codes for stones were the comparison group. Predictor: Stone formers were placed into 5 mutually exclusive categories after reviews of medical charts: incident symptomatic kidney, recurrent symptomatic kidney, asymptomatic kidney, bladder only, and miscoded (no stone). Outcomes: End-stage renal disease (ESRD), mortality, cardiovascular mortality, and cancer mortality. Analytical Approach: Cox proportional-hazards models with adjustment for baseline comorbidities Results: Overall, 65/6984 (0.93%) stone formers and 102/28044 (0.36%) non-stone formers developed ESRD over a mean follow up period of 12.0 years. After adjusting for baseline hypertension, diabetes mellitus, dyslipidemia, gout, obesity, and chronic kidney disease, the risk of ESRD was higher in recurrent symptomatic kidney (HR, 2.34; 95% CI, 1.08-5.077), asymptomatic kidney (HR, 3.94; 95% CI, 1.65-9.43) and miscoded (HR, 6.18; 95% CI, 2.25-16.93) stone formers, but not in incident symptomatic kidney or bladder stone formers. The adjusted risk of all-cause mortality was higher in asymptomatic kidney (HR, 1.40; 95% CI, 1.18-1.67) and bladder (HR, 1.37; 95% CI, 1.12-1.69) stone formers. Chart review of asymptomatic and miscoded stone formers suggested an increased risk of adverse outcomes related to diagnoses including urinary tract infection, cancer, and musculoskeletal or gastrointestinal pain. Conclusions: The higher risk of ESRD in recurrent symptomatic compared to incident symptomatic kidney stone formers suggests that stone events are associated with kidney injury. The clinical indication for imaging in asymptomatic stone formers, the correct diagnosis in miscoded stone formers, and the cause of a bladder outlet obstruction in bladder stone formers may explain the higher risk of ESRD or death in these groups.

Miniaturized percutaneous nephrolithotomy (PCNL) procedures have gained increased popularity in recent years. They aim to reduce percutaneous tract size in order to lower complication rates, while maintaining high stone-free rates. Recently, miniaturized PCNL techniques have further expanded, and can currently be classified into mini-PCNL, minimally invasive PCNL (MIP), Chinese mini-PCNL (MPCNL), ultra-mini-PCNL (UMP), micro-PCNL, mini-micro-PCNL, and super-mini-PCNL (SMP). However, despite its minimally-invasive nature, its potential superiority in terms of safety and efficacy when compared to conventional PCNL is still under debate. The aim of this review is to summarise different available modalities of miniaturized PCNL, details of instruments involved, and their corresponding safety and efficacy. In particular, this article highlights the role of the SMP and our experience with this novel technique in management of urolithiasis. Overall, miniaturized PCNL techniques appear to be safe and effective alternatives to conventional PCNL for both adult and pediatric patients. Well-designed, randomized studies are required to further investigate and identify specific roles of miniaturized PCNL techniques before considering them as standard rather than alternative procedures to conventional PCNL.