(Solution) Imam Abdulrahman Bin Faisal University Systematic Review and Meta-Analysis Research Paper

Solution

Comparing Retrograde Intrarenal Surgery and Percutaneous Nephrolithotomy for Pediatric Urinary Stones Management: A Systematic Review and Meta-Analysis of Efficacy and Safety

Abstract

Purpose: The purpose of this review is to compare PCNL and RIRS regarding efficacy and surgical complications.

Methodology: Clinical trials were selected from multiple databases and were searched from inception until September 2024. Screening of the studies on the basis of title and abstract against the inclusion criteria was conducted by two independent reviewers. The quantitative synthesis of the results was performed using STATE BE 19 for MAC.

Results: Nineteen studies involving 1410 pediatric patients were included. The pooled analysis revealed no significant differences between the two approaches regarding stone-free rate (RR = 0.96, 95% CI [0.88 – 1.04], p = 0.30), postoperative fever (RR = 1.04, 95% CI[0.66 – 1.65], p = 0.85), and operation time (MD = -7.59, 95% CI [-17.56 to 2.38], p = 0.14). Incidence of pooled complications was less in the RIRS group compared with PCNL (P = 0.04).

Conclusion: Overall, both treatment options were almost comparable, and the choice between PCNL and RIRS should be guided by clinical judgment.

KEYWORDS: Nephrolithotomy, Retrograde intrarenal surgery, Pediatric, Kidney stone.

Introduction

The prevalence of kidney stones in pediatrics has notably increased, with studies indicating rates between 2% to 10% in pediatric populations. The increase in prevalence could be attributable to many risk factors, which include decreased water intake, increased high-sodium meals, and obesity. According to a study conducted in Egypt, the reported prevalence of kidney stones in pediatric patients was 7%, which highlights a significant concern regarding mortality and morbidity [1]. Furthermore, the recurrence rate of kidney stones in the pediatric population is quite high, with rates reaching up to 35%. Accordingly, careful monitoring and prevention strategies are necessary [2].

Regarding demographic differences, the male-to-female ratio in the pediatric population suffering from kidney stones is 1.15:1, which means boys are more likely to develop kidney stones and multiple surgical interventions [2]. The risk factors for stone formation can be classified into metabolic and non-metabolic categories. Non-metabolic factors include age, sex, race, congenital anomalies of the urinary tract, and family history. Metabolic factors include hypercalciuria, hyperoxaluria, hypocitraturia, and cystinuria. Metabolic factors contribute to the pathophysiology of stone formation [1-3].

Percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS) are the two main surgical interventions used to treat pediatric renal stones. PCNL is usually used in cases with larger kidney stones or when other methods fail. PCNL involves making a small incision in the back to gain access to the kidney and directly remove the stone. However, RIRS uses a flexible scope guided through the urinary tract to visualize the stone and fragment it locally without incisions [2,4].

Both methods aim to remove the stone with minimal complications and recovery time. RIRS is usually employed in smaller kidney stones measuring less than 2 cm due to the ability of the scope to reach difficult areas of the kidney [5]. On the other hand, PCNL is preferred for larger stones over 2 cm, as it provides direct access for more effective removal and often achieves higher stone-free rates (SFR) with a single procedure [6].

Both procedures have surgical risks. While PCNL is regarded as more effective, surgical complications such as bleeding, organ injury, radiation exposure, infections, possible need for blood transfusion, and postoperative pain [5]. On the other hand, RIRS is regarded as less invasive. However, complications can still occur, such as ureteral injuries, urinary tract infections, and the need for multiple procedures for larger stones [6].

There is a significant gap in high-quality comparative research on PCNL and RIRS for pediatric renal stones. Most studies have small sample sizes and retrospective designs, and some are limited to preschool-aged children, affecting their broader applicability [7]. Therefore, there is a need for systematic reviews and meta-analyses to evaluate the efficacy and safety of these techniques in children. This study aims to address this gap by comparing PCNL and RIRS, focusing on stone-free rates, operative time, and complications to provide guidance for clinical practice and future research.

Methods

This systematic review and meta-analysis is in line with the guidelines provided by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) [8]. In the case where a study used median and interquartile range as the units of measure for continuous outcomes, a specific conversion method provided by Lou et al. [9] and Wan et al. [10] was used to convert to mean and standard deviation.

PRISMA

Figure 1 PRISMA flow-chart of the results of the literature search

2.1. Data Sources and Search Strategy

The databases PubMed, OVID CENTRAL, Web of Science, Google Scholar, and Embase were searched from inception until September 2024. The used PubMed search strategy is as follows: “(((((((flexible ureterosocopy) OR (flexible ureteropyeloscopy)) OR (FURS)) OR (retrograde intra-renal surgery)) OR (RIRS)) OR (procedure, ureteroscopic surgical[MeSH Terms])) AND (((PCNL) OR (percutaneous nephrolithotomy)) OR (percutaneous nephrolithotomy[MeSH Terms]))) AND ((((Pediatric*) OR (infant*)) OR (adolescen*)) OR (child*)”. To further identify eligible studies, a hand search of the citations of relevant articles and included studies was conducted.

2.2. Study Selection

The studies were selected based on the following criteria: 1. Comparing RIRS and PCNL for the treatment of urinary stones; 2. The studied population was exclusively the pediatric population 3. Reporting our outcomes of interest. The primary outcome was the stone-free rate after treatment. Secondary outcomes include operative duration, postoperative fever, Clavien Dindo complications, and the pooled complications as a composite outcome, pooling all the complications reported in each study.

Studies were excluded if the involved adult patients or RIRS and PCNL weren’t included as comparative arms.

Table 1: Detailed study characteristics. Numerical data is presented in absolute numbers (n). RIRS: retrograde intra-renal surgery; PCNL: percutaneous nephrolithotomy.

2.3. Data Extraction and Study Quality Assessment

The results of the literature search were imported into EndNote Reference Library software. Duplicates were removed automatically by the software. Screening of the studies on the basis of title and abstract against the inclusion criteria was conducted by two independent reviewers (SA and AB). The shortlisted studies’ full texts were obtained and evaluated against the inclusion criteria. Any discrepancies were resolved by agreement and consensus with a third reviewer (AS). Data pertaining to the study characteristics, including study year, country, duration, types of intervention, and detailed patient characteristics, were extracted into pre-formed tables. The quality assessment of included studies was assessed by two reviewers independently using the Newcastle-Ottawa scale (NOS) [11,12].

Table 2: Detailed participant data. Numerical data is presented in either mean and standard deviation (SD) or in absolute numbers (n). RIRS: retrograde intra-renal surgery; PCNL: percutaneous nephrolithotomy.

Table 3: Quality assessment of included studies using the Newcastle-Ottawa scale (NOS).

2.4. Statistical Analysis

All the statistical analysis was conducted using STATE 19 BE for MAC. The primary and secondary endpoints were synthesized using a Dersimonian-Laird random-effects model. Continuous outcomes were summarized as mean differences (MDs) with corresponding 95% confidence intervals (CIs), while dichotomous outcomes were expressed as risk ratios (RRs) with 95% CIs. A p-value < 0.05 was considered statistically significant.

Between-study heterogeneity was assessed using the Higgins I² statistic and chi-square test. Significant heterogeneity was defined as I²> 50% and a chi-square p-value < 0.1. To determine the robustness of the findings, the leave-one-out analysis was executed, whereby each study was sequentially removed to ensure that the pooled effect was not driven by any single study. Potential publication bias was assessed visually by funnel plots, which depict the relationship between study effect size and standard error.

Results

3.1. Results of the Literature Search

The literature search yielded a total of 502 studies (Figure 1). After the removal of duplicated studies, 437 studies remained for screening, of which 21 were eligible for full-text review. Six new studies were identified as eligible and fit the inclusion criteria, combined with the 13 studies of the previous review, totaling 19 eligible studies.

3.2. Study Characteristics and Quality Assessment

Across the 19 studies, a total of 1410 pediatric patients with urinary stones requiring treatment were assessed. 690 patients were treated with RIRS, while 720 were treated with PCNL. The baseline study characteristics and detailed population characteristics are shown in Tables 1 and 2, respectively. The details of the quality assessment of the included studies are shown in Table 3, all studies included had a relatively high score with ranges between 6-9 indicating a low risk of bias.

3.3. Results of the Meta-Analysis

The findings from the meta-analysis of 19 observational studies comparing RIRS with PCNL for pediatric urinary stone treatment are depicted in Figures 2 through 8. The figures provide forest plots showing the effect sizes for the outcomes analyzed.

Stone-Free Rate

All 19 studies reported data on the stone-free rate (RIRS group, 690 patients, 563 events; PCNL group, 720 patients, 643 events). The pooled analysis indicated no significant difference in the stone-free rate between the RIRS and PCNL, with an RR of 0.96 (95% CI [0.88 – 1.04], p = 0.30) (Figure 2). The between-study heterogeneity was negligible (I² = 0%, p = 1) (Figure 2).

Importantly, the leave-one-out analysis supported the robustness of the results, demonstrating that the exclusion of any single study did not substantially alter the pooled estimate, as illustrated in Supplementary Figure 1.

Finally, the visual inspection of the funnel plot showed moderate asymmetry around the pooled estimate, indicating the possibility of publication bias, as displayed in Supplementary Figure 2.

Operation Time

Sixteen studies provided data regarding operative duration (RIRS group, 561 patients; PCNL group, 620 patients). No statistically significant difference was observed between the two approaches regarding operative time (MD = -7.59, 95% CI [-17.56 to 2.38], p = 0.14) (Figure 3). Notably, the pooled studies exhibited a significant heterogeneity (I²= 97.71%, p = 0.001) (Figure 3).

Postoperative Fever

Postoperative fever was reported in 11 studies, encompassing 389 patients in the RIRS group and 421 patients in the PCNL group. The pooled analysis revealed no statistically significant difference between the two groups regarding postoperative fever (RR= 1.04, 95% CI [ 0.66 to 1.65; p = 0.85), with associated non-significant heterogeneity (I²= 2.94%, p = 0.41) (Figure 4).

Clavien-Dindo Grade I Complications

Twelve studies provided data on the incidence of Clavien-Dindo grade I complications (RIRS groups, 520 patients, 52 events; PCNL group, 538 patients, 64 events). The meta-analysis indicated no significant difference between the two groups with a pooled RR of 0.71 (95% CI [0.51 – 1.00], p = 0.05) (Figure 5). There was no significant heterogeneity across studies (I²= 0%, p = 0.76) (Figure 5).

Clavien-Dindo Grade II Complications

Please click the following icon to access this assessment in full