Drivers of 30-day Readmission, Reoperation, and Length of Stay Following Clipping Surgery of Unruptured Aneurysms in Elderly: A National Surgical Quality Improvement Program (NSQIP) Study

Introduction: The elderly population is increasing worldwide, with a consistent increase in the incidence of aneurysms. There are limited data evaluating the rate and predictors of reoperation and readmission after microsurgical clipping of unruptured aneurysms in the elderly

Methods: Data on elderly patients (≥ 65 years) who underwent surgical clipping of an unruptured aneurysm between 2016 and 2020 were extracted from the prospective National Surgical Quality Improvement Program registry (NSQIP). Multivariable logistic regression evaluated the independent predictors of nonroutine hospital discharge, length of stay (LOS), 30-day reoperation, and readmission. Shapley additive explanations (SHAP) were calculated for feature importance using the best-performing model.

Results: A total of 367 elderly patients underwent surgical clipping for both ruptured (N=142) and unruptured aneurysms (N=225). Among the 225 unruptured cases, 11.6% (N=26) were readmitted and 6.2% (N=14) were reoperated after 30 days. The mean LOS is 6.53 days (± 7.15). Most patients were discharged home (N=160; 71.1%). Morbidity and morbidity probabilities were 2.15% and 3.8%, respectively. Male sex; preoperative BUN; preoperative creatinine and preoperative platelet count (p < 0.05) are more likely to predict 30-day readmission. Male sex , history of cancer , and history of COPD (p < 0.05) are more likely to predict reoperation. LOS was predicted with simple aneurysm , history of sepsis; history of COPD; elective surgery; operative time and days till the operation (p < 0.05). Machine learning using SHAP showed that BUN, platelet count, and sex had the highest impact on readmission; WBC, hematocrit, and sodium levels had the highest impact on reoperation, while operative time and history of sepsis had the highest impact on LOS.

Conclusion : Our predictive model validates risk stratification of outcomes of patients undergoing microsurgical clipping of unruptured cerebral aneurysms in the elderly.