title: Adherence to endovascular aortic aneurysm repair device instructions for use guidelines has no impact on outcomes.
abstract: OBJECTIVE
  Prior reports have suggested unfavorable outcomes after endovascular aortic aneurysm repair (EVAR) performed outside of the recommended instructions for use (IFU) guidelines. We report our long-term EVAR experience in a large multicenter registry with regard to adherence to IFU guidelines.
  
  
  METHODS
  Between 2000 and 2010, 489 of 1736 patients who underwent EVAR had preoperative anatomic measurements obtained from the M2S, Inc, imaging database (West Lebanon, NH). We examined outcomes in these patients with regard to whether they had met the device-specific IFU criteria. Primary outcomes were all-cause mortality and aneurysm-related mortality. Secondary outcomes were endoleak status, adverse events, reintervention, and aneurysm sac size change.
  
  
  RESULTS
  The median follow-up for the 489 patients was 3.1 years (interquartile range, 1.6-5.0 years); 58.1% (n = 284) had EVAR performed within IFU guidelines (IFU-adherent group), and 41.9% (n = 205) had EVAR performed outside of IFU guidelines (IFU-nonadherent group). Preoperative anatomic data showed that 62.4% of the IFU-nonadherent group had short neck length, 10.2% had greater angulation than recommended, 7.3% did not meet neck diameter criteria, and 20% had multiple anatomic issues. A small portion (n = 49; 10%) of the 489 patients were lost to follow-up because of leaving membership enrollment (n = 28), moving outside the region (n = 10), or discontinuing image surveillance (n = 11). There was no significant difference in any of the primary or secondary outcomes between the IFU-adherent and IFU-nonadherent groups. Aneurysm sac size change at any time point during follow-up also did not differ significantly between the two groups. A Cox proportional hazard model showed that IFU nonadherence was not predictive of all-cause mortality (hazard ratio, 1.0; P = .91). Similarly, IFU nonadherence was not identified as a risk factor for aneurysm-related mortality or adverse events in stepwise Cox proportional hazards models.
  
  
  CONCLUSIONS
  In our cohort of EVAR patients with detailed preoperative anatomic information and long-term follow-up, overall mortality and aneurysm-related mortality were unaffected by IFU adherence. In addition, rates of endoleak and reintervention after initial EVAR were similar, suggesting that lack of IFU-based anatomic suitability was not a driver of outcomes.
authors: Division of Surgery, University of California, San Francisco, San Francisco, Calif.
authors: Joy
authors: J
authors: Walker
authors: Division of Research, Kaiser Permanente, Oakland, Calif.
authors: Lue-Yen
authors: LY
authors: Tucker
authors: Division of Vascular Surgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH.
authors: Philip
authors: P
authors: Goodney
authors: Division of Surgery, University of California, San Francisco-East Bay Medical Center, Oakland, Calif.
authors: Leah
authors: L
authors: Candell
authors: Division of Vascular Surgery, The Permanente Medical Group, San Francisco, Calif.
authors: Hong
authors: H
authors: Hua
authors: Division of Vascular Surgery, The Permanente Medical Group, San Francisco, Calif.
authors: Steven
authors: S
authors: Okuhn
authors: Division of Vascular Surgery, The Permanente Medical Group, Santa Clara, Calif.
authors: Bradley
authors: B
authors: Hill
authors: Division of Vascular Surgery, The Permanente Medical Group, South San Francisco, Calif. Electronic address: robert.w.chang@kp.org.
authors: Robert W
authors: RW
authors: Chang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000401:mortality / Q000601:surgery*; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation* / Q000401:mortality; D002140:California; D002423:Cause of Death; D057867:Endoleak / Q000209:etiology / Q000401:mortality; D057510:Endovascular Procedures / Q000295:instrumentation* / Q000401:mortality; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D019983:Guideline Adherence; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000209:etiology* / Q000401:mortality / Q000517:prevention & control; D016016:Proportional Hazards Models; D012042:Registries; D012086:Reoperation; D012307:Risk Factors; D015607:Stents; D016019:Survival Analysis