We sought to determine the risk factors associated with late mortality or complications (thoracoabdominal aortic aneurysm [TAAA] life-altering events [TALE]: a composite of mortality, permanent paraplegia, permanent dialysis, and stroke) for patients who had undergone endovascular or open TAAA repair.We performed a population-based study of patients who had undergone TAAA repair in Ontario, Canada, from 2006 to 2017. The association of baseline risk factors with mortality and complications after repair was examined using Cox hazards models with hospital-specific random effects. The survival of patients who had undergone TAAA repair was compared with that of controls without TAAAs. The two groups were matched by age, sex, area of residence, and average annual household income. The type of repair (endovascular vs open) was included in all models.We identified 664 adults (mean age, 69.3 ± 10.6 years; 71% men) who had undergone TAAA repair. At 5 and 8 years, survival was 55.0% (95% confidence interval [CI], 49.8%-60.1%) and 44.6% (95% CI, 40.4%-49.6%) for patients who had undergone TAAA repair vs 85.6% (95% CI, 83.9%-87.1%) and 76.3% (95% CI, 73.8%-78.8%) for the control population, respectively (hazard ratio [HR], 1.97; 95% CI, 1.67-2.32; P .01). For the TAAA group, freedom from TALE was 49.2% (95% CI, 44.7%-53.7%) and 37.3% (95% CI, 33.1%-42.4%) at 5 and 8 years of follow-up, respectively. On multivariable analysis, the risk factors associated with mortality during follow-up included older age (HR, 1.21 per 5-year increase; 95% CI, 1.13-1.28), peripheral artery disease (HR, 1.46; 95% CI, 1.03-2.09), hypertension (HR, 1.58; 95% CI, 1.03-2.43), congestive heart failure (HR, 1.78; 95% CI, 1.34-2.36), and urgent procedures (HR, 2.27; 95% CI, 1.74-3.00). A lower rate of death was observed for those with previous coronary revascularization (HR, 0.63; 95% CI, 0.41-0.96) and those who had undergone repair at high-volume institutions (60 TAAA repairs during the study period; HR, 0.71; 95% CI, 0.55-0.91). Older age, chronic kidney disease, congestive heart failure, and urgent procedures were associated with a higher rate of TALE. The type of repair (endovascular vs open) was not associated with mortality or TALE.TAAA repair was associated with reduced long-term survival compared with the general population, regardless of the mode of treatment. Urgent or emergent repair was the most profound risk factor for late adverse events. The type of repair (endovascular vs open) was not a predictor of long-term death or complications. Previous coronary revascularization and treatment performed at a high-volume institution were associated with improved late outcomes for patients undergoing TAAA repair.