Introduction

Urolithiasis, a condition characterized by the formation of stones within the urinary tract, presents a significant burden on health, contributing to substantial morbidity. The primary objective of urolithiasis intervention is the complete elimination of stones while mitigating patient morbidity. Treatment options for upper ureteral stones include extracorporeal shock wave lithotripsy, ureteroscopy (URS), and percutaneous nephrolithotomy¹.

The historical evolution of endoscopic techniques has markedly influenced the diagnosis and manage ment of upper urinary tract diseases^2,3. The introduc tion of the holmium laser: YAG has notably increased the efficacy of endoscopic lithotripsy, becoming the preferred method for such interventions due to its safety profile within the urinary tract⁴. However, its invasive nature bears potential risks and complications.

Urolithiasis affects individuals across all age groups. Current clinical practice guidelines often focus on a mid dle-aged, healthy population, leading to a lack of specific treatment recommendations for patients at the extremes of the age spectrum⁵. Flexible URS (F-URS) has emerged as the first-line therapy for mid or distal ureteral stones that require intervention and an optimal approach for managing non-lower pole renal stones ≤ 2 cm that has been unresponsive to prior interventions or ≤ 10 mm lower pole renal stones. Advancements in flexible ureteroscope technology have substantially enhanced its diagnostic and therapeutic utility, improving its efficacy while reducing adverse events⁵. Nonetheless, evidence evaluating the safety and efficacy of this procedure in the elderly population remains limited.

The extension of the human lifespan and increased life expectancy is evident in the national population pyramids⁶. This demographic shift leads to a growing population of older individuals, often with higher mor bidity, and increased anesthetic risks during surgical procedures, potentially influencing success rates and complication rates in urological procedures.

This study aims to assess the efficacy and safety of the F-URS procedure in individuals over 65 years, in comparison to a cohort of patients under 65 years, evaluating potential age-related differences in its out comes and safety.

Materials and methods

The study design was a multicenter retrospective observational study. We analyzed anonymized data from the institutional medical record system of two cen ters in Cali, Colombia, from June 2015 to May 2018.

We included patients undergoing F-URS for the man agement of intrarenal or proximal ureteral stones who, based on clinical criteria and diagnosis, classified for this procedure as being the best therapeutic option. The diagnosis was confirmed by a non-contrast computerized axial tomography. Patients with missing data on study variables, active urinary tract infections, bleeding diathesis, or stones larger than 2 cm were excluded from the study. In addition, patients below 18 years old were not included in the study. For the analysis, patients were stratified into two groups: group A (n: 30) defined as aged patients (> 65 years), and Group B (n: 171) as patients of non-advanced age (< 65 years). All patients underwent F-URS under gen eral anesthesia, with the same endoscopic equipment, a FLEXOR-2 nephroscope, with the subsequent pas sage of an 11 French (Fr) ureteral access sheath, and a 276-nanometer Holmium: YAG fiber to perform lithotripsy.

We collected the patient's demographic and clinical characteristics, including age, sex, anesthetic risk, comorbidities, stone characteristics, and location. These characteristics were analyzed and compared between the two groups, as well as the operative and post-operative results, such as ureteral access sheath time, double J catheter use, and stone-free rate. Stone-free rate (SFR) was defined as radiologically stone-free or without fragments larger than 2mm on a standard abdominal radiograph 4 weeks after treatment. Statistical analysis was performed with descriptive sta tistics using STATA with the information registered in a dataset in EXCEL. Categorical variables were expressed as numbers and percentages. Quantitative variables were expressed as medians.

Results

Of the 216 patients identified, 201 patients were ana lyzed. The mean age of patients in Group A was 75 (SD ± 4.5), where 16 (53.3%) were women and 14 (46.7%) were men; in Group B, the mean age was 51 (SD ± 10) of which 66 (38.5%) were women and 105 (61.5%) were men (Table 1).

Overall, Group A patients had more comorbidities present. We found that hypertension had the highest prevalence, with a total of 63.3% in Group A, followed by diabetes mellitus (16.7%) and coronary heart dis ease (16.7%). No significant differences were found among the body mass index of the patients in both groups. Pre-operative Double J catheter use was more prevalent in Group A compared to Group B (50% vs. 43.2%), with a comparable mean time of around 12 weeks (Table 1).

The anesthetic risk was measured with the classifi cation of the American Society of Anesthesiology (ASA), Group A had more patients classified in ASA 2 (50%) and ASA 3 (23.3%) compared with Group B (45% and 8.8%) (Table 1).

The stone location was predominantly on the right side for both groups, followed by single ureteral location (23.9%), pelvic (23.3%), and lower calyceal (23.3%) for Group A; and pelvic (24.6%) for Group B. The mean stone size was 13 mm for Group A and 11.8 mm for Group B (Table 2). A ureteral access sheath was used in all patients, with a longer procedural time recorded for Group A compared to Group B (41.4 min vs. 35.7 min). A post-operative Double J catheter was inserted in 83.3% of Group A patients, similar to 81.2% in Group B.

The final SFR was 76.6% for Group A and 79.5% for Group B (Table 3) with no significant statistical differ ences (p = 0.149). Furthermore, no statistically signifi cant differences were found for Grades II and IV ureteral injury between the two groups (p = 0. 859). Patients in Group A had 90% of Grade I ureteral trauma like Group B with 92.9%. No anesthetic or post-operative complications were reported. All patients recovered and were discharged home.

Discussion

The historical development of ureteral stone manage ment, traced from initial reports by Pérez-Castro and Hoffman-Bagley to subsequent assessments of URS's effectiveness, shows a significant evolution in treatment approaches, resulting in progressive enhancements in the SFR. F-URS has since emerged as the contempo rary standard for managing urolithiasis, with the American Society of Urology recommending this approach as first-line option, particularly for non-lower pole renal stones smaller than 2 cm and ureteral lithiasis. Moreover, it presents an opportunity for managing larger stones in select cases or instances of failed percutaneous nephrolithotomy^7-10.

As the global population ages, the surge in older indi viduals with comorbidities demands careful consideration in surgical interventions, particularly in stone disease man agement. The analysis from the Clinical Research Office of the World Endourological Society confirms the low com plication rates and efficacy of F-URS^10,11.

Our study contributes valuable insights, indicating a comparable safety profile in managing renal and ureteral stones in older people. Despite their higher opera tive and anesthetic risks, our findings did not reveal significant differences in intraoperative or post-operative complications between the aged and non-aged groups.

Similarly, SFRs and significant ureteral injuries showed no significant differences between the two groups. This suggests that F-URS presents minimal peri and post-operative impact, being a viable and safe option for the management of stones in the aged population.

Our study strengthens the growing evidence for URS in older adults with stones. While our SFR mirrors the SFR of 73.9% reported by Solomon et al., their larger study population with a higher mean age provides fur ther robust data on the efficacy of URS in aged people. These findings, along with their low complication rate of 20.7% for minor complications and 5.7% for major complications, further prove the role of URS as a safe and effective treatment option for these patients¹².

Furthermore, these findings are consistent with those from Tamiya et al., who conducted an analysis on recurrent kidney stones in both young and elderly patients after URS. The final SFR of all cases was 93.3% and they found no significant differences in the SFR or the rate of surgical complications between the young group and the elder groups¹³.

Considering the morbidity and complication rates asso ciated with percutaneous nephrolithotomy, especially in older patients with comorbidities, a multi-step intervention using F-URS might offer a promising alternative for man aging larger stones. This approach holds the potential to minimize surgical morbidity in the aged, aligning with the increasing need for safer surgical techniques in this demographic group¹⁴.

Conclusions

The present study demonstrated that F-URS in aged patients is a safe and effective procedure with a mini mum rate of complications and satisfactory surgical results. Age did not show to have a negative impact on intraoperative or post-operative results, and it appears to be comparable in terms of SFR. F-URS should not be withheld from older patients seeking for manage ment of kidney and ureteral stones.