This study revealed no significant difference in the incidence of intraoperative complications of RIRS for urolithiasis between the octogenarian and younger patient groups. The incidence of postoperative complications was significantly higher in the octogenarian; however, the difference in multivariate analysis and propensity score-matched analysis between the octogenarian and younger patient groups was not significantly associated with the occurrence of postoperative complications. Furthermore, RIRS in the octogenarian was an effective treatment with a high success rate.
A variety of conditions that affect stone formation (reduced fluid intake due to immobility and dysphagia) and comorbidities (urinary tract infection, hypertension, diabetes, and decreased renal function) are thought to contribute to stone morbidity in the elderly . Previous epidemiological studies have reported an increased prevalence of kidney stone disease in the elderly [3, 4]. According to global demographic data, the prevalence of kidney stones among the elderly aged 65 years and older in developed countries is estimated to increase up to 19.1% in males and 9.4% in females by 2050 . Additionally, the elderly are at increased risk of infections due to kidney stones . However, to our best knowledge, few studies have examined the safety and efficacy of RIRS for urolithiasis in the elderly, and little evidence support RIRS in patients over 80 years of age. Japan has one of the highest ratios of elderly people in the world , therefore, we believe that reporting clinical outcomes of RIRS for urolithiasis in octogenarians at an institution in Japan is very meaningful.
This study included 1,207 patients, of whom 166 (13.8%) were octogenarians. Our data showed that all intraoperative and postoperative complications were found in 105 (8.7%) and 151 (12.5%) patients, respectively. The occurrence rate of perioperative complications in this study was similar to those reported in the previous studies [16–19]. This study revealed no significant difference in the incidence of intraoperative complications of RIRS between the octogenarian and younger patient groups, and age itself was not significantly associated with the occurrence of postoperative complications in multivariate analysis and propensity score-matched analysis. Generally, aging is related to a gradual decline in a reserve capacity, even in individuals without underlying comorbidities, which decreases the ability of elderly patients to tolerate stress . Thus, older age is an independent predictor of increased postoperative complications . However, few studies have focused on the elderly; however RIRS for urolithiasis has been reported as a feasible procedure in the elderly, and age itself should not be considered a limiting factor, similar to our study [6, 7]. Additionally, it has also been reported that RIRS could be safely applied to octogenarians . Considering these findings and our data, RIRS for urolithiasis was considered a feasible operation even in octogenarians, and age itself may not be a risk factor for postoperative complications following RIRS.
This study showed significant predictors of complications, including female sex, ASA score of ≥ 3, diabetes mellitus history, and prolonged operative time. Similar to our study, female gender and medical complexity were predictive of urinary tract infection in the Clinical Research Office of the Endourological Society Ureterorenoscopy Global Study (CROES Global Study URS) database . Furthermore, past reports indicate that female sex and ASA score were the independent predictors of the occurrence of postoperative complications following RIRS [22–24]. Moreover, longer operative time was associated with postoperative fever [19, 23]. Moses et al. reported that operative times of > 120 min were associated with postoperative fever, similar to our study . As other predictors of complications, a history of pyelonephritis obstructive or positive urine culture has been reported as a risk factor for postoperative fever [26, 19, 23]. In our study, postoperative complications occurred more frequently in patients with a history of pyelonephritis, but this was not statistically significant. Reducing postoperative complications after RIRS for urolithiasis is important; however, preventing complications in patients at high risk of complications, such as gender and medical history as described above, may not be easy. However, the operative time can be somewhat managed by urologists. For patients who are expected to undergo lengthy RIRS, a two-step RIRS or an alternative approach for urolithiasis should be considered.
Currently, the optimal definition of SF has no universally accepted protocol. Patients with residual fragments of > 2 mm are more likely to require retreatment; thus, a consensus is emerging that SF should be ≤ 2 mm . Our institution has also previously reported that a residual fragment of ≥ 4 mm was a risk factor for future intervention . Therefore, we defined SF as no evidence of > 2 mm stones on postoperative KUB. CT is the most accurate modality for detecting urinary calculi and is capable of detecting uric acid calculi at the expense of high cost and radiation exposure. KUB is hindered by lower sensitivity for stones of < 5 mm and cannot detect radiolucent stones . Additionally, obesity may decrease sensitivity. However, it has the advantage of low exposure and low cost. In our study, the SFR was significantly higher in the octogenarian group than in the younger group, which was 80.1% in the octogenarian group and 68.2% in the younger group, and was comparable to the SFR of 65–79% reported in the literature . The kidney stones were smaller and the operative time was slightly longer in the octogenarian group. The physicians might have tried SF more diligently on the octogenarians with lower activity levels, which may have been a bias. However, considering some errors in imaging modalities or surgical bias, RIRS for urolithiasis could be effectively applied to octogenarians with a high success rate.
This study has certain limitations. A major limitation of this study is its retrospective design. Another limitation is the potential for patient selection bias. The choice of observing patients with kidney and/or ureter stones, performing RIRS, or performing other treatments, such as extracorporeal shock wave lithotripsy or percutaneous nephrolithotomy, depends on many factors, including the surgeon’s preference and the patient’s clinical condition. However, regardless of these limitations, our present study supports the clinical benefit of RIRS for urolithiasis in octogenarians.