Does the 5-Item Modified Frailty Index Predict Adverse Outcomes after Retrograde Intrarenal Surgery? A Case-Control Study by the RIRSearch Group.

Objectives: We aim to assess whether severely frail patients have an increased risk of complications and worse surgical outcomes after retrograde intrarenal surgery. Methods: The data of 340 consecutive patients undergoing retrograde intrarenal surgery to treat upper tract urinary stones were analyzed retrospectively. The 5-item modified frailty index (mFI-5) was used to assess the frailty status. Using a cutoff value of score 2 in the mFI-5 score, patients were divided into two groups: patients with an mFI-5 score <2 were assigned to a non-frail (Group 1) group, and patients with an mFI-5 score ≥2 were assigned to a frail (Group 2) group. The patients' demographics, stone characteristics, operative outcomes, and complication rates were compared between the groups. The primary objective was to examine whether the surgical outcomes were much better in non-frail patients. Results: After matching confounding factors, Group 1 comprised 255 patients, and Group 2 comprised 85 patients. The baseline characteristics were similar between the groups. There were no statistically significant differences in terms of the median operation time and length of hospital stay among groups. There were no significant differences between groups for intraoperative complication rates (7.6% and 9.4%, respectively; P = .47) and postoperative complication rates (13.8% and 11.8%, respectively; P = .71), and stone-free rates (70.9% versus 72.9%, respectively; P = .73). Conclusions: Retrograde intrarenal surgery is an efficient and feasible treatment option for upper urinary tract stones in severely frail patients.