Purpose: To describe and compare mid-term outcomes from 2 real-world data collection efforts on fenestrated and branched endovascular aortic repair (fbEVAR) for complex abdominal aortic aneurysms (AAAs) in France and to evaluate the potential of health care databases for long-term post-market surveillance (PMS) and continued reimbursement approval. Methods: Two real-world studies were conducted in France: a retrospective health care database study (SNDS) and a prospective clinical study. In the SNDS study, data from implantation and/or hospital stays occurring during follow-up were extracted for all patients treated with the study devices from April 2012 to December 2018. In the clinical study, high-risk patients undergoing fbEVAR with the study devices were enrolled consecutively at 15 sites in France from December 2016 to November 2018. Results: Data from 1073 patients were extracted from SNDS and compared with analogous variables from 186 patients in the clinical study. Most demographic details were similar between studies (SNDS vs clinical: mean age, 71.9 vs 71.8 years; men, 91.0% vs 89.8%), as was 30-day mortality (SNDS: 5.5%, clinical: 4.3%). Patients received custom-made fenestrated or branched devices (SNDS: 80.7%, clinical: 96.2%) or CE-marked Zenith Fenestrated devices (SNDS: 19.3%, clinical: 3.8%). Initial or technical success was above 94% for both studies. Two-year freedom from all-cause mortality was 80.0% (SNDS) and 85.1% (clinical study). Two-year freedom from aneurysm-related mortality was 93.8% (SNDS) and 94.6% (clinical study). Detailed imaging outcomes were not captured within SNDS; however, information on secondary procedures to restore patency was available and used as a surrogate measure for secondary interventions. Two-year freedom from secondary interventions was 73% for the SNDS study. In the clinical study, at 2 years, aneurysm stability or shrinkage was observed in 92.3% of patients, freedom from target vessel primary patency loss was above 95% for all visceral target vessels, and freedom from secondary interventions was 79.1%. Conclusion: Real-world outcomes from the SNDS and clinical study suggest positive mid-term outcomes in high-risk populations following fbEVAR for complex AAAs. The similarities between these studies suggest that the use of health care databases may be an alternative to prospective clinical studies for long-term follow-up and PMS.