We identified 396 eligible surgeons, and 240 (61%) contributed cases to the study. The median number of cases per surgeon was 18 (interquartile range 8-32). In this study we have included only those patients who underwent surgery. We do not know how many operations were cancelled because the carotid stenosis had progressed to occlusion before surgery or how many patients had a disabling or fatal stroke before they could undergo surgery.
Phase 1 details were complete for 5513 patients (including 16 from the private sector) by 31 March 2008 (from 240 surgeons in 120 hospitals). Baseline phase 2 data were available for 4964 cases (from 206 surgeons in 105 hospitals), and complete data were available for the 4404 patients who attended follow-up appointments. The total number of cases listed on hospital episode statistics as “carotid endarterectomy with or without patching” for the data collection period of this study was 9913, giving a 56% rate of case submission (table 1). In England, monthly case ascertainment compared with hospital episode statistics data (figure) remained constant across the data collection period.
Regional contributions to survey by country and hospital/trust
Month by month hospital episode statistics for England
Of the 5513 patients, 3751 (68%) were men, with mean age of 70 (71 for women). Twelve per cent of all patients were aged over 80 (660/5513), 2.9% over 85 (160/5513), and 0.6% over 90 (31/5513). Most patients were British white (95%, 5115/5377), the next largest group being British Asian (1.1%, 58/5513), which is consistent with the known predominance of carotid disease in the white population. Twenty one per cent (1178/5509) had diabetes, and 32% (1762/5513) had a history of ischaemic heart disease or chronic heart failure. Thirty one per cent (1671/5476) were current smokers. The commonest risk factor for stroke, hypertension, was present in 80% of patients (4403/5492), with 1.4% (79/5492) untreated on admission.
Sixteen per cent of cases (889/5513) were recorded as being asymptomatic, with the 84% remaining having some symptom attributable to carotid disease. Of these, 41% (1914/4624) had a transient ischaemic attack, 35% (1634/4624) had stroke, 20% (916/4624) had amaurosis fugax, and 3% (160/4624) none of these three symptoms. Previous ipsilateral carotid surgery was recorded for 1.8% (99/5513) of patients and angioplasty for 0.4% (20/5513).
The referral source was recorded for all cases. Stroke (38%, 2117/5513) or care of the elderly (13%, 717/5513) physicians referred most patients, with neurologists (11%, 596/5513) and general practitioners (13%, 701/5513) referring substantial numbers. The 1382 other referrals came from sources including cardiologists, ophthalmologists, and other vascular surgeons. The fastest pathway from referral to surgery was through neurologists (median delay 25 days, interquartile range 10-63 days) and stroke physicians (30, 16-67 days). Referrals through care of the elderly physicians (48, 24-85 days) and general practitioners (68, 34-151 days) were considerably slower.
There was considerable delay between the most recent symptom and surgery (table 2). Nearly a third (1372/4591) of patients waited more than 12 weeks, and only 20% (944/4591) underwent surgery within two weeks.
Table 2 Delay between most recent symptom and surgery
Delays from referral to operation were considerable. The median delay from referral to surgery was 40 days (17-84 days). During the survey there was a trend towards reduction in this delay from 43 (19-88) to 38 (16-81) to 34 (13-79) days (dividing the data collection into three equal time periods). Once admitted, 15% (818/5513) had their operation on the day of admission, and 94% (5186/5513) were operated on within two days.
Preoperatively, 90% of patients were taking a statin (4982/5513) and 32% (1781/5512) were taking a β blocker. Nearly all (5378/5513) were taking at least one antithrombotic drug before surgery (table 3). Antiplatelet therapy was stopped before surgery in 11% (514/4627) of those taking aspirin and 51% (468/922) taking clopidogrel (usually in addition to aspirin). Five per cent (289/5363, 15 missing data) were taking warfarin, which was almost always stopped (273/284, 96%) before surgery (table 3).
Table 3 Proportion of antithrombotic drug use before and after endarterectomy
Surgery on the left carotid artery was slightly more common (52%, 2863/5504; data missing for nine) than on the right. Some 3733 patients underwent confirmatory imaging (a second ultrasound examination after the initial duplex scan to confirm that the carotid artery was still patent before surgery) of the ipsilateral carotid before operation, and the level of stenosis was available for all but 16 cases. Seven per cent (269/3717) of patients had 50-69% stenosis, 55% (2032/3717) had 70-89% stenosis, and 35% (1285/3717) had 90-99%. One per cent (28/3717) had less than 50% stenosis, and 3% (103/3717) were ungraded. The level of stenosis in the contralateral carotid artery was missing for 25 cases and not imaged in 1075 cases. Fifty six per cent of cases (1462/2633) had less than 50% contralateral stenosis, 14% (381/2633) had a level of 50-69%, 19% (498/2633) had 70-99%, and 11% (292/2633) had an occluded artery. The methods used to assess duplex stenosis were not specified, but, in the organisational surveys, hospitals were found to have used different methods (NASCET (North American symptomatic carotid endarterectomy trial), ECST (European carotid surgery trial), and common carotid artery (CCA)), which could result in variation in stenosis; however, this was not the only assessment of the stenosis, and magnetic resonance angiography (MRA) and computed tomography angiography (CTA) were often carried out, contributing to the decision to undertake surgery.
Phase 2 (follow-up) data were known for 4964 (90%) patients. Ninety five per cent (4593/4818) were offered an appointment, and, of these, 96% (4404/4593) attended, with median time from operation to follow-up of 50 days (41-65 days). Rankin scores at follow-up were known for 4389 patients and were broadly similar to the scores at discharge (data not shown; they are less reliable because they measure a broad range of disability, which is not necessarily related to stroke).
Most patients (91%, 4499/4964) were taking antithrombotic drugs, the type being specified for 4471: aspirin in 85%, clopidogrel or dipyridamole, or both, in 35%, and warfarin in 5%, despite about 17% of patients having atrial fibrillation (table 3). Eighty four per cent (4158/4964) were taking statins, and 21% (1054/4934) were taking β blockers.
Inpatient mortality was 0.5% (29/5512). The principal cause of inpatient death was stroke, followed by myocardial infarction. Risk of inpatient death increased with age (0.1% (1/820) at <60 years, 0.6% (23/4032) at 60-80 years, 0.8% (5/660) at >80 years. The 30 day mortality was 1.0% (48/4944); 30 day survival was not known for seven patients. Of the 5512 patients, 101 (1.8%) were reported to have had a stroke as an inpatient and of these 67 had the stroke within 24 hours of surgery, which gives a 24 hour stroke rate of 1.2%. Thirty patients had a stroke after discharge, three of whom had already had a stroke during their inpatient stay. The rate of stroke from admission to follow-up was 2.6% (124/4681) (table 4).
Reported outcomes and complications. Figures are percentages (numbers) of patients