Materials and Methods
This study is a retrospective analysis of patients over 65 years of age who undergoing PCNL or RIRS for kidney stones at the Ministry of Health University Izmir Bozyaka Training and Research Hospital between April 2011 and January 2020. The data were driven from the electronic medical records of all the patients consecutively. Patients who had history of neuromuscular disease, congenital renal anomalies, coagulopathy, morbid obesity, skeletal deformity, solitary kidney and <65 years of age were excluded from the study. A total of 161 patients, were divided into two groups according to surgical technique; PCNL Group n = 89, and RIRS Group n=72. Comparisons were made among patient demographics, and perioperative and postoperative outcomes.
The following data were recorded by the two surgeons (SY and MS) immediately postoperatively: patient demographics (age, gender, body mass index, operation side, location of the stones, stone burden, Metabolic Syndrome: there were at least two illnesses (diabetes mellitus, hypertension, hyperlipidemia and obesity) and preoperative data (table-1). Perioperative data included surgery time, fluoroscopy time, length of stay, Change in Hgb and Change in creatinine (table-2). Postoperative complications were noted according to the Clavien scoring system (table-3).10 Complications according to Clavien scoring system were divided two groups; Minor complications = Clavien grades I-II, and Major complications = Clavien grades III-IV-V. Charlson comorbidity index was measured for all patients. Correlation analysis was used for intraoperative and postoperative results with CCI (table-4). Complications rates were compared between RIRS and PCNL according to the CCI (table-5)
Sterile urine culture was detected in all patients before operation. Ceftriaxone was given as prophylaxis before the operation and continued until the nephrostomy tube was removed. No Nephrotoxic drugs were used before, during, or after the operation for any patient.
Stone burden was calculated with square millimeters in all patients : length x width x π x 0.25, where π is a mathematical constante qualto 3.14.11 In multiple intrarenal stones, stone burden was calculated one by one and then all of them were collected. The estimated GFR was  calculated using the Cockcroft–Gaultformula (CrCl = ([140-age] × weight in kg) / (serum creatinine × 72) x 0,85 (if female).12 All PCNL and RIRS interventions were performed by two surgeons (SY and MS).