Longer Hospital Length of Stay and Emergency Surgical Intervention are Associated with Lower Rates of Mortality In Elderly Patients with Ruptured Abdominal Aortic Aneurysm: An Analysis of 7,214 Patients

Introduction: We aimed to determine predictors for in-hospital mortality for elderly patients with ruptured abdominal aortic aneurysms (AAA) undergoing emergency admission. Materials and Methods: This was a retrospective cohort study utilizing the National Inpatient Sample (NIS) Database, 2005–2014, on elderly patients with ruptured AAA undergoing emergency admission. ICD-9 code 441.3 was used to identify patients with ruptured AAA. Male versus female sex, survived versus deceased patients, and operated versus not-operated ones were compared for various patient characteristics. A multivariable logistic regression with backward elimination and a generalized additive model (GAM) were implemented to evaluate the associations between potential risk factors and mortality. Results: A total of 7,214 patients aged 65 and older with ruptured AAA were included. About 31% of total sample, 26% of survived, and 36% of deceased were female. Mortality rate was higher in older patients, females, and those who were not operated on (40.6%) versus those that were (74.5%). Age, sex, healthcare insurance, severity of illness subclass, hospital length of stay, total charges, and several comorbidities had significant association with mortality in univariable models. Multivariable logistic regression with backward elimination confirmed age (odds ratio[OR]=1.04; 95% confidence interval [CI]=1.03–1.05; p<0.001), sex (OR=1.23; 95%CI=1.07–1.41; p=0.004), hospital length of stay (OR=0.87; 95%CI=0.86–0.88; p<0.001), bacterial infection (OR=3.79; 95%CI=3.07–4.68; p<0.001), cardiac disease (OR=1.97; 95%CI=1.71–2.28; p<0.001), liver disease (OR=2.90; 95%CI=2.22–3.77; p<0.001), fluid and electrolyte disorders (OR=1.34; 95%CI=1.18–1.52; p<0.001), and coagulopathy (OR=1.96; 95%CI=1.04–1.37; p=0.01) to be the independent predictors of mortality. Age showed a linear association with mortality; whereas, hospital length of stay had a significant L-shaped association. Elderly patients emergently admitted for ruptured AAA had the lowest risk of mortality with hospital stays greater than seven days (EDF=13.91, p<0.0001). Conclusion: Longer hospital length of stay (>7 days) of emergently admitted elderly patients with ruptured abdominal aortic aneurysm was associated with better outcomes and lower risk of mortality. Surgical intervention was also associated with much lower rate of mortality, while increasing age was associated with higher rate of mortality. In elderly patients admitted for ruptured abdominal aortic aneurysm, every one year older than 65, increased the odds of mortality by 4% and female sex increased the odds of mortality by 23%.