title: Evaluation of the learning curve for fenestrated endovascular aneurysm repair.
abstract: OBJECTIVE
  The objective of this study was to evaluate the learning curve for fenestrated endovascular aortic aneurysm repair (FEVAR).
  
  
  METHODS
  Data were collected prospectively on all FEVAR procedures conducted by a single surgeon between June 2007 and January 2015. During the study period, 136 FEVARs were performed, and this experience was divided into four quartiles each consisting of 34 cases. Clinical outcomes evaluated included perioperative death and major complications. Process outcomes included length of procedure, fluoroscopy time, contrast material use, estimated blood loss, and intensive care unit length of stay.
  
  
  RESULTS
  During the study period, there was a statistically significant increase in the complexity of cases as evidenced by an increase in the proportion of cases with two or more fenestrations from 52.9% in the first quartile to 88.2% in the fourth quartile (P = .001). Despite this, there was a steady decrease in the proportion of patients suffering perioperative death or major complications from 23.5% in the first quartile to 8.8% in the fourth quartile. After adjustment for potential confounding factors, the odds of death or major complication were cut by 52.4% per quartile increase (95% confidence interval [CI], 7.8%-75.5%; P = .028). In addition, among cases with two or more fenestrations, geometric mean length of procedure was reduced from 223.8 minutes in the first quartile to 149.6 minutes in the fourth quartile, and geometric mean fluoroscopy time was reduced from 58.6 minutes in the first quartile to 31.5 minutes in the fourth quartile. After adjustment, there was an estimated 9.9% reduction in geometric mean procedure length per quartile increase (95% CI, 3.5%-15.9%; P = .003) and a 17.6% reduction in geometric mean fluoroscopy time per quartile increase (95% CI, 10.9%-23.8%; P < .0001).
  
  
  CONCLUSIONS
  Despite an increase in case complexity, there was evidence for significant improvement in important clinical and process outcomes during the study period. We believe that much of this improvement was attributable to several key advances in the FEVAR procedure that were instituted during the study period and are discussed herein.
authors: Division of Vascular Surgery, Department of Surgery, University of Washington, Seattle, Wash. Electronic address: starnes@uw.edu.
authors: Benjamin W
authors: BW
authors: Starnes
authors: Kaiser Permanente, Honolulu, Hawaii.
authors: Michael T
authors: MT
authors: Caps
authors: Brooke Army Medical Center, San Antonio, Tex.
authors: Zachary M
authors: ZM
authors: Arthurs
authors: Division of Vascular Surgery, Department of Surgery, University of Washington, Seattle, Wash.
authors: Billi
authors: B
authors: Tatum
authors: Division of Vascular Surgery, Department of Surgery, University of Washington, Seattle, Wash.
authors: Niten
authors: N
authors: Singh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000401:mortality / Q000601:surgery*; D017545:Aortic Aneurysm, Thoracic / Q000000981:diagnostic imaging / Q000401:mortality / Q000601:surgery*; D016063:Blood Loss, Surgical; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods* / Q000401:mortality; D002983:Clinical Competence; D003287:Contrast Media / Q000008:administration & dosage; D057510:Endovascular Procedures / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods* / Q000401:mortality; D005260:Female; D005471:Fluoroscopy; D017052:Hospital Mortality; D006801:Humans; D059032:Learning Curve; D007902:Length of Stay; D008297:Male; D061646:Operative Time; D011183:Postoperative Complications / Q000209:etiology / Q000401:mortality; D011474:Prosthesis Design; D058996:Quality Improvement; D019984:Quality Indicators, Health Care; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014861:Washington
chemical_list: D003287:Contrast Media