2007 Abstracts: Lost To Follow-Up: A Potential, Under Appreciated Limitation of Endovascular Aneurysm Repair

Background It has long been appreciated that close lifetime follow-up after endovascular aneurysm repair (EVAR) is necessary to avoid potential late catastrophic complications which may jeopardize long-term outcome. However, follow-up rates for non-research EVAR patients in general practice are unknown and the impact of incomplete follow-up has not been reported. The purpose of this study, therefore, is to test the hypothesis that late follow-up rates for EVAR in general practice are inferior to those reported from clinical trials, consequently causing poorer long-term outcomes.
Methods From February 1999 to December 2005, 310 EVAR's were performed at our institution, of which 302 survived and were eligible for follow-up. Of these, 47 were performed as part of an industry sponsored clinical trial (study patients). While all cases were registered into a prospective vascular database, responsibility for compliance to a standardized follow-up protocol (one month, 6 months, 12 months, 18 months, 24 months, then yearly for life, each with an imaging study to evaluate for endoleak) was assigned to office scheduling staff for patients not in clinical trials (non-study patients) and to research nurses for study patients. For the non-study patients, office visit cancellations were identified by computer and rescheduled; patients not found were left telephone messages and then sent a registered letter requesting follow-up. Follow-up for study patients was managed via close, regular communication by the research nurses. For the purposes of this study, all charts were reviewed and follow-up classified as good (< one missed follow-up) or lost (> 2 consecutive missed follow-ups). Overall survival and complication rates were analyzed. Kaplan Meier life table analyses were performed on survival, time to major complication and time to re-intervention; differences between groups were assessed using the log-rank test. Student's t-test was used to compare means, and proportions of outcome events between the groups were compared using Fisher's Exact test.
Results Of the 302 patients, good follow-up was attained in 203 (67.2%). Ninety-nine (32.8%) were lost to follow-up. Mean follow-up was 34.7 + 22 months in the good follow-up group and 18.8 + 18.6 months in the lost group (p<0.001). While the five-year survival (63.9%-good vs. 64.0%-lost), the five year re-intervention rate (22.3%-good vs. 10.8%-lost) and the incidence of known endoleak (14.8%-good vs. 9.1%-lost) were statistically similar in both groups, the incidence of major complications (defined as adverse events requiring urgent operation including aneurysm rupture, symptomatic endoprosthesis migration or graft infection) was higher in the lost to follow-up group (6.1% vs. 0.5%; p=0.006). While there was no difference in late mortality or complication rates for study patients compared to non-study patients, follow-up compliance was substantially better in the study group (44.8 + 23.7 months vs. 26.8 + 20.9 months; p<0.001).
Conclusions Actual long-term follow-up rates for EVAR in general practice are substantially inferior to those reported in controlled trials and represent a potential, under appreciated limitation of EVAR. This report also questions whether findings in clinical trials on the efficacy of EVAR have general applicability for use in a community practice.