Trends in the In-Hospital Stroke Rate Following Carotid Endarterectomy in California and Maryland

Back to Annual Meeting
Back to Program

Susanna L. Matsen, MD, David C. Chang, PhD, MPH, MBA, Bruce A. Perler, MD, MBA, Glen S. Roseborough, MD, G. Melville Williams, MD.
Johns Hopkins University, Baltimore, MD, USA.

BACKGROUND:
We sought to examine the outcome of carotid endarterectomy (CEA), and in particular the rate of perioperative strokes, over the past decade.
METHODS:
We performed retrospective analysis of 10 years (1994-2003) of the Maryland and 5 years (1999-2003) of the California hospital discharge databases. Inclusion criteria were: 1) International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) procedure code 38.12 (endarterectomy of the vessels of the head and neck other than intracranial vessels) in the primary but not in any secondary position, and 2) ICD-9 diagnosis code 433.00 - 433.91 (occlusion/stenosis, precerebral artery), and 3) Diagnosis-Related Group (DRG) 5 (extracranial vascular procedure). Symptomatic patients were identified by history of previous stroke (ICD-9 codes 342 or 438), transient ischemic attack (435 or 781.4), or amaurosis fugax (362.34 or 368.12). In-hospital strokes were identified by ICD-9 codes of 997.0, 997.00, 997.01, and 997.09.
RESULTS:
A total of 23,237 CEA cases were identified in the Maryland data, with 169 in-hospital strokes over 10 years (0.73%), whereas the 51,331 California CEA saw 232 in-hospital strokes over 5 years (0.45%). The stroke rate in Maryland was 2.12% in 1994, 1.47% in 1995, then ranged between 0.3% and 0.6% from 1996 to 2003. The decrease in strokes was seen more dramatically among symptomatic patients, where the rate was 3.82% in 1994, 4.44% in 1995, then ranged between 0.9% and 2.3% from 1996 to 2003. A similar decrease was seen in the asymptomatic patient stroke rate but to a lesser extent: 1.64% in 1994, 0.8% in 1995, then ranging between 0.2% and 0.4% from 1996 to 2003. The low recent stroke rates were confirmed by the California data (0.44% to 0.48% from 1999 to 2003). Changes in the death rate for CEA over this timeframe have not been as pronounced, ranging from 0.33 to 0.58% for Maryland, and 0.78 to 0.91% for California. The years 1994 and 1995 saw a significantly higher percentage of patients treated by low-volume surgeons (<= 10 CEAs/year) in Maryland than the years 1996 and 1997 (15.2% vs. 13.4%, P = 0.014).
CONCLUSIONS:
A dramatic decrease in the in-hospital stroke rates in Maryland occurred around 1995. The lower proportion of CEAs performed by low-volume surgeons from 1994/1995 as compared with 1996/1997 may in part explain the decrease in stroke rate over these 4 years. The stroke rates seen in Maryland over the past 5 years are similar to those seen in California over the same period. The in-hospital stroke rate now for carotid endarterectomy is approximately 0.5% based on analysis of data from two states.

Back to Annual Meeting
Back to Program