Relationship between the regional and national incidence of transient ischaemic attack and stroke and performance of carotid endarterectomy

Regional variation in patient selection and treatment for carotid artery disease in the Vascular Quality Initiative

OBJECTIVE

Previous studies involving large administrative data sets have revealed regional variation in the demographics of patients selected for carotid endarterectomy (CEA) and carotid artery stenting (CAS) but lacked clinical granularity. This study aimed to evaluate regional variation in patient selection and operative technique for carotid artery revascularization using a detailed clinical registry.

METHODS

All patients who underwent CEA or CAS from 2009 to 2015 were identified in the Vascular Quality Initiative (VQI). Deidentified regional groups were used to evaluate variation in patient selection, operative technique, and perioperative management. χ² analysis was used to identify significant variation across regions.

RESULTS

A total of 57,555 carotid artery revascularization procedures were identified. Of these, 49,179 patients underwent CEA (asymptomatic: median, 56%; range, 46%-69%; P < .01) and 8376 patients underwent CAS (asymptomatic: median, 36%; range, 29%-51%; P < .01). There was significant regional variation in the proportion of asymptomatic patients being treated for carotid stenosis <70% in CEA (3%-9%; P < .01) vs CAS (3%-22%; P < .01). There was also significant variation in the rates of intervention for asymptomatic patients older than 80 years (CEA, 12%-27% [P < .01]; CAS, 8%-26% [P < .01]). Preoperative computed tomography angiography or magnetic resonance angiography in the CAS cohort also varied widely (31%-83%; P < .01), as did preoperative medical management with combined aspirin and statin (CEA, 53%-77% [P < .01]; CAS, 62%-80% [P < .01]). In the CEA group, the use of shunt (36%-83%; P < .01), protamine (32%-89%; P < .01), and patch (87%-99%; P < .01) varied widely. Similarly, there was regional variation in frequency of CAS done without a protection device (1%-8%; P < .01).

CONCLUSIONS

Despite clinical benchmarks aimed at guiding management of carotid disease, wide variation in clinical practice exists, including the proportion of asymptomatic patients being treated by CAS and preoperative medical management. Additional intraoperative variables, including the use of a patch and protamine during CEA and use of a protection device during CAS, displayed similar variation in spite of clear guidelines. Quality improvement projects could be directed toward improved adherence to benchmarks in these areas.

Comparison between quantification methods of carotid artery stenosis and computed tomographic angiography

PURPOSE

The purpose of this study was to compare 3 percentage carotid artery measurement methods (the North American Symptomatic Carotid Endarterectomy Trial [NASCET], the European Carotid Surgery Trial [ECST], and the Carotid Stenosis Index [CSI]) and 1 millimeter method (direct millimeter measurement) to evaluate the difference and correlation between them.

MATERIALS AND METHODS

Seven hundred ninety-two patients (591 men; age: mean, 63 years; range, 32-91 years) studied by using a multi-detector row computed tomographic scanner for a total of 1584 carotid arteries were retrospectively analyzed. Each carotid stenosis was measured according to 4 measurement methods (the NASCET, the ECST, the CSI, and the direct millimeter measurement). Carotid arteries with near-occlusion condition were excluded. The Kolmogorov-Smirnov Z test was used to test the normality of continuous variable groups. Comparison of derived ratio-percent methods was performed by using the Bland-Altman plots, and receiver operating characteristic curves were calculated. Correlation coefficients were also calculated by using a nonparametric Spearman correlation. A P < 0.05 was considered to mean statistical significance.

RESULTS

Four hundred sixteen carotid arteries were excluded, and in the remaining 1168 ones, a strength correlation according to quadratic regression between the NASCET and ECST methods was observed (Spearman rho coefficient, 0.948; P < 0.0001). An inverse correlation according to linear regression was observed between the NASCET and the direct millimeter measurement (Spearman rho coefficient, -0.972; P < 0.0001); the CSI shows a quadratic regression with the NASCET, a linear regression with the ECST, and an inverse linear regression with the direct millimeter measurement (Spearman rho coefficient, 0.946, 0.932, and -0.939 respectively). The cutoff values for 50% and 70% NASCET stenosis were 2.36 and 1.51, respectively.

CONCLUSIONS

Our study results indicate that the direct millimeter measurement of stenosis, by using appropriate equations, can reliably predict NASCET-, ECST-, and CSI-type percent stenoses. The use of direct millimeter measurement may remove the pitfalls and the discrepancies deriving from the use of different ratio-percent methods.

Assessment of intracranial arterial stenosis with multidetector row CT angiography: a postprocessing techniques comparison

BACKGROUND AND PURPOSE

It was demonstrated the some patients with stroke have intracranial stenosis of 50% or greater and the identification of intracranial arterial stenosis is extremely important in order to plan a correct therapeutical approach. The aim of this study was to assess the image quality and intertechnique agreement of various postprocessing methods in the detection of intracranial arterial stenosis.

MATERIAL AND METHODS

Eighty-five patients who were studied by using a multidetector row CT scanner were retrospectively analyzed. A total of 2040 segments were examined in the 85 subjects. Intracranial vasculature was assessed by using MPR, CPR, MIP, and VR techniques. Two radiologists reviewed the CT images independently. Cohen weighted kappa statistic was applied to calculate interobserver agreement and for image accuracy for each reconstruction method. Sensitivity, specificity, PPV, and NPV were also calculated by using the consensus read as the reference.

RESULTS

Two hundred fifteen (10.5%) stenosed artery segments were identified by the observers in consensus. The best intermethod kappa values between observers 1 and 2 were obtained by VR and MIP (kappa values of 0.878 and 0.861, respectively), whereas MPR provided the lowest value (kappa value of 0.282). VR showed a sensitivity for detecting stenosed segments of 88.8% and 91.6% for observers 1 and 2, respectively. The highest positive predictive value was also obtained by VR at 95% and 99% for observers 1 and 2, respectively. Image accuracy obtained by using VR was the highest among all reconstruction methods in both observers (185/255 and 177/255 for observers 1 and 2, respectively).

CONCLUSIONS

The results of our study suggest that VR and MIP techniques provide the best interobserver and intertechnique concordance in the analysis of intravascular cranial stenosis.

Regional variation in carotid artery stenting and endarterectomy in the Medicare population

BACKGROUND

To describe geographic variation in population-based rates of carotid artery stenting (CAS) and carotid endarterectomy (CEA) performed in Medicare beneficiaries.

METHODS AND RESULTS

Medicare claims and enrollment data were used to calculate age, sex, and race-adjusted rates of CAS and CEA for Medicare beneficiaries in each of 306 hospital referral regions between 1998 and 2007. Procedures were identified using a combination of Current Procedural Terminology codes as well as diagnostic and procedural ICD-9 codes. Overall, the rate of carotid revascularization has fallen slightly over the last decade (3.8 procedures per 1000 in 1998, 3.1 procedures per 1000 in 2007; P<0.0001). Although the use of CEA decreased, from 3.6 to 2.5 procedures per 1000 beneficiaries in 2007 (P<0.0001), the use of CAS has increased >4-fold between 1998 and 2007, growing from 0.1 to 0.6 CAS procedures per 1000 beneficiaries (P<0.0001). Further, CAS rapidly disseminated across the country over the last decade. In 1998, 66% of hospital referral regions had a hospital that performed CAS; however, by 2007, nearly all (95%) hospital referral regions performed CAS (P<0.0001). Last, in regions with the highest utilization rates of CAS, it appeared that CAS was performed as a substitute for CEA. There was little evidence that CAS was being performed in addition to CEA, as no correlation existed between regional rates of CAS and CEA (r=0.06).

CONCLUSIONS

Even though CEA was used less frequently in 2007 than 1998, the use of CAS has grown significantly. Although regional variation in the use of CEA has remained fairly constant, regional variation has increased in the use of CAS. Given these changes in practice patterns, careful examination of the efficacy and cost-effectiveness of CAS is necessary.

Health services research in the public healthcare system in Hong Kong: an analysis of over 1 million antihypertensive prescriptions between 2004-2007 as an example of the potential and pitfalls of using routinely collected electronic patient data

BACKGROUND

Increasing use is being made of routinely collected electronic patient data in health services research. The aim of the present study was to evaluate the potential usefulness of a comprehensive database used routinely in the public healthcare system in Hong Kong, using antihypertensive drug prescriptions in primary care as an example.

METHODS

Data on antihypertensive drug prescriptions were retrieved from the electronic Clinical Management System (e-CMS) of all primary care clinics run by the Health Authority (HA) in the New Territory East (NTE) cluster of Hong Kong between January 2004 and June 2007. Information was also retrieved on patients' demographic and socioeconomic characteristics, visit type (new or follow-up), and relevant diseases (International Classification of Primary Care, ICPC codes).

RESULTS

1,096,282 visit episodes were accessed, representing 93,450 patients. Patients' demographic and socio-economic details were recorded in all cases. Prescription details for anti-hypertensive drugs were missing in only 18 patients (0.02%). However, ICPC-code was missing for 36,409 patients (39%). Significant independent predictors of whether disease codes were applied included patient age > or = 70 years (OR 2.18), female gender (OR 1.20), district of residence (range of ORs in more rural districts; 0.32-0.41), type of clinic (OR in Family Medicine Specialist Clinics; 1.45) and type of visit (OR follow-up visit; 2.39). In the 57,041 patients with an ICPC-code, uncomplicated hypertension (ICPC K86) was recorded in 45,859 patients (82.1%). The characteristics of these patients were very similar to those of the non-coded group, suggesting that most non-coded patients on antihypertensive drugs are likely to have uncomplicated hypertension.

CONCLUSION

The e-CMS database of the HA in Hong Kong varies in quality in terms of recorded information. Potential future health services research using demographic and prescription information is highly feasible but for disease-specific research dependant on ICPC codes some caution is warranted. In the case of uncomplicated hypertension, future research on pharmaco-epidemiology (such as prescription patterns) and clinical issues (such as side-effects of medications on metabolic parameters) seems feasible given the large size of the data set and the comparability of coded and non-coded patients.

CT and ultrasound in the study of ulcerated carotid plaque compared with surgical results: potentialities and advantages of multidetector row CT angiography

BACKGROUND AND PURPOSE

Ulceration is a severe complication of carotid plaque. The purpose of this study was to evaluate the role and the diagnostic efficacy of multidetector row CT angiography (MDCTA) and ultrasound (US) echo color Doppler (US-ECD) in the study of patients with carotid plaque complicated by ulceration through the comparison with the surgical observation.

MATERIALS AND METHODS

From January 2004 to October 2005, 237 patients, for a total of 474 carotid arteries, studied at first with color Doppler US, were analyzed using CT angiography. A total of 103 patients underwent a carotid endarterectomy. We analyzed stenosis degree, plaque composition, and presence of ulcerations. In a second phase, the data were compared with the surgical results when the MDCTA indicated surgical intervention.

RESULTS

MDCTA found 31 ulcerations; the surgical confirmation underlined a 93.75% sensitivity and a 98.59% specificity. US-ECD performances were 37.5% and 91.5% for sensitivity and specificity, respectively. The number of patients who showed plaque ulcerations increased with the severity of stenosis. Furthermore, ulcerations of the carotid plaque occurred more often proximal than distal to the point of maximum stenosis, and this trend increased with the severity of the stenosis. We also determined that fatty plaques were more likely to be affected by ulcerations.

CONCLUSIONS

The results of our study suggest that MDCTA detects with higher sensitivity and specificity the presence of ulcerated plaque compared with US-ECD, which has been demonstrated to be less effective in this evaluation. Considering the high MDCTA sensitivity and specificity for detection of plaque ulceration, we therefore recommend MDCTA as a useful step for correct presurgical planning.

Multidetector-row CT angiography in the study of atherosclerotic carotid arteries

Pathologies of the carotid arteries, and in particular atherosclerosis, are now an important medical problem. Stroke is the third leading cause of severe disability in the Western World leading to millions of deaths every year. Extracranial carotid atherosclerotic disease is the major risk factor for stroke. In years, with the advent of multidetector-row CT (MDCT) scanners and the use of specific angiographic protocols (MDCTA), CT imaging of the carotid arteries has become increasingly effective. In addition, the volume data obtained can be further rendered to generate high-quality two-dimensional and three-dimensional images. The purpose of this study was to review the atherosclerotic carotid arteries, their complications and how MDCTA depicts them, underlining the benefits and pitfalls of this diagnostic technique.

Training for Carotid Intervention: Preparing the Next Generation

BACKGROUND

Carotid interventions are performed to reduce the cumulative risk of stroke. The success of the procedure is dependent upon maintaining low operative risk. This article reviews the current state of training for both carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS).

METHODS

Medline searches were performed to identify articles with the combination of the following key words: carotid, endarterectomy, stent, training, assessment and simulation. Manual searches of the reference lists and related papers was conducted.

RESULTS

Training and assessment for CEA and CAS follows the traditional apprenticeship model. There is no formal training protocol or objective means of assessment for either carotid endarterectomy or stenting. Models and simulators to allow for training and assessment away from the operative theatre have been developed, and exist for both CEA and CAS.

CONCLUSION

The technology exists to allow for both training and assessment of competency to take place in a controlled and objective environment for both CEA and CAS. The use of simulation needs to be robustly evaluated and assessed to both complement and augment existing training programs to ensure that the highest standards of care are maintained for treatment of carotid territory disease. Objective competency based training and assessment is no longer unattainable. Simulators augment this process and without them operative exposure is sporadic and crisis management infrequent.

Risk of stroke in people with type 2 diabetes in the UK: a study using the General Practice Research Database

AIMS/HYPOTHESIS

Risk estimates for stroke in patients with diabetes vary. We sought to obtain reliable risk estimates for stroke and the association with diabetes, comorbidity and lifestyle in a large cohort of type 2 diabetic patients in the UK.

MATERIALS AND METHODS

Using the General Practice Research Database, we identified all patients who had type 2 diabetes and were aged 35 to 89 years on 1 January 1992. We also identified five comparison subjects without diabetes and of the same age and sex. Hazard ratios (HRs) for stroke between January 1992 and October 1999 were calculated, and the association with age, sex, body mass index, smoking, hypertension, atrial fibrillation and duration of diabetes was investigated.

RESULTS

The absolute rate of stroke was 11.91 per 1,000 person-years (95% CI 11.41-12.43) in people with diabetes (n = 41,799) and 5.55 per 1,000 person-years (95% CI 5.40-5.70) in the comparison group (n = 202,733). The age-adjusted HR for stroke in type 2 diabetic compared with non-diabetic subjects was 2.19 (95% CI 2.09-2.32) overall, 2.08 (95% CI 1.94-2.24) in men and 2.32 (95% CI 2.16-2.49) in women. The increase in risk attributable to diabetes was highest among young women (HR 8.18; 95% CI 4.31-15.51) and decreased with age. No investigated comorbidity or lifestyle characteristic emerged as a major contributor to risk of stroke.

CONCLUSIONS/INTERPRETATION

This study provides risk estimates for stroke for an unselected population from UK general practice. Patients with type 2 diabetes were at an increased risk of stroke, which decreased with age and was higher in women. Additional risk factors for stroke in type 2 diabetic patients included duration of diabetes, smoking, obesity, atrial fibrillation and hypertension.

BPH with coexisting overactive bladder dysfunction--an everyday urological dilemma

The aim of this study was to use a systematic schedule, including urodynamics, to describe the rate of coexisting overactive bladder (OB) in patients with bladder outlet obstruction (BOO) caused by benign prostatic hyperplasia (BPH). We also identified differences between the patients with pure BOO compared with those with BOO combined with OB (BOO + OB). One hundred and sixty-two men referred to our clinic due to LUTS were included. Patients with a history that might affect their bladder function were excluded. After cystometry and pressure-flow studies, the patients were divided into pure BOO and BOO + OB. Of the 162 men, 55% had pure BOO. BOO + OB was found in 45%. Age, s-PSA, voided volume, and obstruction grade differed significantly between the groups. The patients with BOO + OB were older, had a higher s-PSA, voided smaller volumes, and were more obstructed. We found no differences in TRUS-volume, Q-max, IPS score, or PVR. There was a strong association between OB and BOO, the percentage of OB increasing with increased obstruction. TRUS-volume, Q-max, IPS score, and PVR did not predict whether the patients had a combined BOO + OB or not. These findings indicate that BOO is a progressive disease, which in time causes pronounced obstruction and perhaps in itself contributes to the development of OB.

Differences in the detection of cyclo-oxygenase 1 and 2 proteins in symptomatic and asymptomatic carotid plaques

BACKGROUND

The expression of cyclo-oxygenase (COX) 1 and 2 has been demonstrated in atherosclerotic arteries. In the present study this was correlated with symptoms arising from a carotid plaque.

METHODS

Carotid plaques from 12 asymptomatic patients were compared with 11 plaques from patients who had had neurological symptoms within the preceding 30 days. Sections were stained with haematoxylin and eosin, elastin van Gieson and goat antihuman antibodies to COX-1 and COX-2. Plaque morphology was correlated with neurological symptoms. The area with positive COX-1 and COX-2 staining was measured by computerized planimetry in entire cross-sections and in specific areas of the plaque.

RESULTS

There was a significant association between cap thinning and plaque rupture with symptoms (P = 0.003). The percentage area of positive staining in entire cross-sections for both COX-1 and COX-2 was significantly greater in symptomatic plaques (P = 0.001 and 0.0004 respectively). Staining in symptomatic plaques was significantly greater in the cap (COX-1: P = 0.001; COX-2: P = 0.0001) and shoulder (COX-1: P = 0.008; COX-2: P = 0.007) regions of the plaque. COX-1 expression in the sclerotic area was not increased (P = 0.15) although COX-2 staining was significantly greater (P = 0.04).

CONCLUSION

Both COX-1 and COX-2 detection was increased in symptomatic plaques. COX may contribute to plaque rupture and the onset of symptoms.

A regional collaborative audit of the practice and outcome of carotid endarterectomy in the United Kingdom. Northern Regional Carotid Endarterectomy Audit Group

OBJECTIVES

To evaluate performance and outcome of carotid endarterectomy (CEA) against agreed audit standards within one English health region. Design a prospective collaborative audit over twelve months (November 1994 to October 1995) involving all surgeons undertaking CEA within one English health region.

METHODS

Audit standards were agreed by all participating surgeons at the outset based on existing national guidelines. Data were abstracted from clinical notes. Outcomes were reviewed by clinicians 30 days post-surgery. A confidential individualised report of the results was provided to each surgeon. A survey of participating surgeons sought to evaluate the audit process.

RESULTS

Ten surgeons performed 139 CEAs on 134 individuals (64% men). Median per surgeon was 12 (range 1-44). Audit standards were generally achieved: 114 (82%) patients had symptomatic carotid stenosis of 70-99%, 14 (10%) were asymptomatic. The median time from first referral to hospital to operation was 4.8 months (interquartile range 3.0-7.3). The rate of disabling stroke or death at 30 days was 2.2% (95% confidence interval (CI) 0.4-6.4%). Surgeons valued the audit.

CONCLUSIONS

The study showed that in the study area CEA was performed predominantly on high-risk patients with low subsequent surgical mortality.

Cost-effective carotid endarterectomy

BACKGROUND

Although carotid endarterectomy is increasing in the UK, there is evidence that the procedure is still underused. Methods of reducing cost in a single vascular unit have been assessed using a continuous audit including outcome measures.

METHODS

A consecutive series of 333 patients admitted over 7 years under a single consultant surgeon were studied. Outcome measures included the rate of perioperative neurological complication of any kind, and death. The length of hospital stay and the number of readmissions within 30 days were recorded prospectively by computerized audit.

RESULTS

Over the interval of the study, the number of preoperative investigations was reduced; angiography and cerebral computed tomography were reserved for specific indications. The median duration of hospital stay decreased from 7 to 2 days. There was no change in the stroke and death rate (3 per cent) during the study and only two patients required readmission within 30 days.

CONCLUSION

Carotid endarterectomy can be performed cost-effectively using non-invasive preoperative investigations for the majority of patients. In-hospital stay has been reduced and the routine use of intensive care replaced by a 2-h stay in theatre recovery. These changes have been achieved without compromising patient safety.

The symptomatic carotid plaque

BACKGROUND

The natural histories of equally severe symptomatic and asymptomatic carotid stenoses are very different, which suggests dichotomy in plaque behavior. The vascular biology of the symptomatic carotid plaque is presented in this review.

SUMMARY OF REVIEW

Histology studies comparing asymptomatic and symptomatic plaques were identified from MEDLINE. Reports in which stenosis severity was not stated or not similar for symptomatic and asymptomatic patients were excluded. In vitro studies and reports from the coronary circulation were reviewed with regard to the vascular biology of the plaque. Histology studies comparing carotid plaques removed from symptomatic and asymptomatic patients reveal characteristic features of unstable plaques: surface ulceration and plaque rupture (48% of symptomatic compared with 31% of asymptomatic, P<0.001), thinning of the fibrous cap, and infiltration of the cap by greater numbers of macrophages and T cells. In vitro studies suggest that macrophages and T cells release cytokines and proteinase, which stimulate breakdown of cap collagen and smooth muscle cell apoptosis and thereby promote plaque rupture.

CONCLUSIONS

Infiltration of inflammatory cells to the surface of carotid plaques may be a critical step in promoting plaque rupture and resultant embolization or carotid occlusion. Further understanding of cell recruitment and behavior in carotid atherosclerosis may allow better detection of unstable plaques and therapeutic methods of plaque stabilization.

Chlamydia pneumoniae and vascular disease

BACKGROUND

There is an increasing body of evidence linking the human pathogen Chlamydia pneumoniae with atherosclerosis.

METHODS

A Medline-based review of the literature was carried out.

RESULTS AND CONCLUSION

Seroepidemiological studies have revealed the possibility that evidence of infection with C. pneumoniae and atherosclerotic disease are related. Studies on human tissue have demonstrated that evidence of the organism can be found in human atherosclerotic tissue by both direct and indirect methods significantly more often than in control vascular tissue. Using animal models it is possible to show that C. pneumoniae can be disseminated haematogenously following pulmonary infection and that it shows a tropism for atherosclerotic tissue. In vitro work has demonstrated that the organism is capable of infecting, surviving and multiplying in cells of the human vascular wall, and that it can provoke a cell-mediated cytokine response which has implications both locally and systemically. Two clinical trials of macrolide antibiotics have demonstrated that they confer increased cardiovascular protection in patients following myocardial infarction. Adequately powered trials are needed to establish the therapeutic role of antibiotics in peripheral arterial disease.