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In-hospital Outcomes Alone Underestimate Rates of 30-Day Major Adverse Events Following Carotid Artery Stenting
Patric Liang, MD, Yoel Solomon, BS, Nicholas J. Swerdlow, MD, Chun Li, MD, Rens R.B. Varkevisser, BS, Livia E.V.M. DeGuerre, MD, Marc L. Schermerhorn, MD.
Beth Israel Deaconess Medical Center, Boston, MA, USA.

Objective:
Outcome studies using databases collecting only hospital discharge data underestimate morbidity and mortality because of failure to capture post-discharge events. The proportion of major adverse events (MAEs) occurring post-discharge is well-characterized in patients undergoing carotid endarterectomy (CEA) but has yet to be characterized following carotid artery stenting (CAS).
Methods:
We retrospectively reviewed all patients undergoing CAS from 2011-2016 using the ACS-NSQIP procedure targeted database to evaluate rates of 30-day MAEs, stratified by in-hospital and post-discharge occurrences. The primary outcome was 30-day stroke/death. Multivariable analysis utilizing purposeful selection was used to identify independent factors associated with in-hospital, post-discharge, and 30-day events.
Results:
Of the 668 patients undergoing CAS, reporting in-hospital outcomes alone would yield a stroke/death rate of 3.0%, grossly underestimating the 30-day stroke/death rate of 4.3%. In fact, 38% percent of stroke/deaths, 30% of strokes, 67% of deaths, 27% of cardiac events (CE), and 24% of stroke/death/CE occur post-discharge (Table). There was a trend towards more stroke/death events occurring post-discharge after treatment of symptomatic compared to asymptomatic patients (57 vs 22%, P = .06). During this same study period, the 30-day stroke/death rate following CEA was 2.6%, with similar proportion of stroke/deaths occurring post-discharge (39%). Following CAS, patients experiencing post-discharge stroke/death events had a trend towards shorter length of stay compared to patients with in-hospital stroke/death (4.3 vs 7.4 days, P = .14). For CAS, use of general anesthesia was independently associated with in-hospital stroke/death (OR 2.7, 95%CI 1.1-6.8, P = .03), whereas history of COPD was associated with post-discharge stroke/death (OR 3.5, 95%CI 0.8-14, P = .09). Non-white ethnicity was independently associated with both post-discharge (OR 9.7, 95%CI 2.4-39, P < .01) and overall 30-day stroke/death (OR 4.1, 95%CI 1.6-10, P < .01), whereas statin use was associated with not having stroke/death in the post-discharge (OR 0.2, 95%CI 0.0-0.7, P = .01) or overall 30-day (OR 0.4, 95%CI 0.2-1.0, P = .04) periods.
Conclusions:
This study demonstrates that a significant number of major adverse events occur after discharge following CAS (similar to CEA) and emphasizes the importance of reporting 30-day outcomes when evaluating post-operative MAEs.

Table. Outcome and Timing of In-hospital, Post-discharge, and 30-day Major Adverse Events of Patients Undergoing Carotid Artery Stenting
Median
days [IQR]
Mean
days +SD
In-hospital event rate
N (%)
Post-discharge event rate
N (%)
30-day event rate
N (%)
Proportion post-discharge events
%
Stroke1 [0,4]3.5 + 6.216 (2.4)7 (1.1)23 (3.4)30
Stroke/TIA1 [0,6.5]5.1 + 8.019 (2.8)12 (1.8)31 (4.6)39
Death18 [9,21]16 + 7.13 (0.5)6 (0.9)9 (1.4)67
Cardiac Event2 [1,3]4.0 + 5.911 (1.7)4 (0.6)15 (2.3)27
Stroke/death2 [0,14]7.5 + 9.320 (3.0)12 (1.8)29 (4.3)38
Stroke/death/2 [0,11]6.3 + 8.429 (4.3)15 (2.3)41 (6.1)24
cardiac Event
TIA, transient ischemic attack; SD, standard deviation


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