Costs and benefits of carotid endarterectomy and associated preoperative arterial imaging: a systematic review of health economic literature

An assessment of the cost-effectiveness of magnetic resonance, including diffusion-weighted imaging, in patients with transient ischaemic attack and minor stroke: a systematic review, meta-analysis and economic evaluation

BACKGROUND

Patients with transient ischaemic attack (TIA) or minor stroke need rapid treatment of risk factors to prevent recurrent stroke. ABCD2 score or magnetic resonance diffusion-weighted brain imaging (MR DWI) may help assessment and treatment.

OBJECTIVES

Is MR with DWI cost-effective in stroke prevention compared with computed tomography (CT) brain scanning in all patients, in specific subgroups or as 'one-stop' brain-carotid imaging? What is the current UK availability of services for stroke prevention?

DATA SOURCES

Published literature; stroke registries, audit and randomised clinical trials; national databases; survey of UK clinical and imaging services for stroke; expert opinion.

REVIEW METHODS

Systematic reviews and meta-analyses of published/unpublished data. Decision-analytic model of stroke prevention including on a 20-year time horizon including nine representative imaging scenarios.

RESULTS

The pooled recurrent stroke rate after TIA (53 studies, 30,558 patients) is 5.2% [95% confidence interval (CI) 3.9% to 5.9%] by 7 days, and 6.7% (5.2% to 8.7%) at 90 days. ABCD2 score does not identify patients with key stroke causes or identify mimics: 66% of specialist-diagnosed true TIAs and 35-41% of mimics had an ABCD2 score of ≥ 4; 20% of true TIAs with ABCD2 score of < 4 had key risk factors. MR DWI (45 studies, 9078 patients) showed an acute ischaemic lesion in 34.3% (95% CI 30.5% to 38.4%) of TIA, 69% of minor stroke patients, i.e. two-thirds of TIA patients are DWI negative. TIA mimics (16 studies, 14,542 patients) make up 40-45% of patients attending clinics. UK survey (45% response) showed most secondary prevention started prior to clinic, 85% of primary brain imaging was same-day CT; 51-54% of patients had MR, mostly additional to CT, on average 1 week later; 55% omitted blood-sensitive MR sequences. Compared with 'CT scan all patients' MR was more expensive and no more cost-effective, except for patients presenting at > 1 week after symptoms to diagnose haemorrhage; strategies that triaged patients with low ABCD2 scores for slow investigation or treated DWI-negative patients as non-TIA/minor stroke prevented fewer strokes and increased costs. 'One-stop' CT/MR angiographic-plus-brain imaging was not cost-effective.

LIMITATIONS

Data on sensitivity/specificity of MR in TIA/minor stroke, stroke costs, prognosis of TIA mimics and accuracy of ABCD2 score by non-specialists are sparse or absent; all analysis had substantial heterogeneity.

CONCLUSIONS

Magnetic resonance with DWI is not cost-effective for secondary stroke prevention. MR was most helpful in patients presenting at > 1 week after symptoms if blood-sensitive sequences were used. ABCD2 score is unlikely to facilitate patient triage by non-stroke specialists. Rapid specialist assessment, CT brain scanning and identification of serious underlying stroke causes is the most cost-effective stroke prevention strategy.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Limited economic evidence of carotid artery stenosis diagnosis and treatment: a systematic review

The objective of this article is to assess the availability and validity of economic evaluations of carotid artery stenosis (CS) diagnosis and treatment.

DESIGN

Systematic review of economic evaluations of the diagnosis and treatment of CS.

METHODS

Systematic review of full economic evaluations published in Medline and Google Scholar up until 28 February 2012. Based on economic checklists (Evers and Philips), the identified studies were classified as high, medium, or low quality.

RESULTS

Twenty-three evaluations were identified. The study quality ranged from 26% to 84% of all achievable points (Evers). Seven studies were of high, eight of medium and eight of low quality. No comparison was made between carotid angioplasty and stenting (CAS) and best medical treatment (BMT). For subjects with severe stenosis, comparisons of carotid endarterectomy (CEA) and BMT were also missing. Three of five studies dealing with pre-operative imaging found that duplex Doppler ultrasound (US) was cost-effective compared with carotid angiogram (AG).

CONCLUSIONS

There is a huge lack of high-quality studies and of studies that confirm published results. Also, for a given study quality, the most cost-effective treatment strategy is still unknown in some cases ('CAS' vs. 'BMT', 'US combined with magnetic resonance angiography supplemented with AG' vs. 'US combined with computer tomography angiography').

Costs of secondary prevention of stroke by carotid endarterectomy

BACKGROUND

We estimated the costs to the Danish National Health Service of preventing stroke due to carotid artery stenosis by carotid endarterectomy (CEA), including costs of identifying patients, Doppler ultrasound (DUS) examination and CEA.

METHODS

Estimations are based on patients with stroke, transient ischemic attacks (TIA) or amaurosis fugax referred for carotid DUS in the municipality of Frederiksberg, Denmark (127,184 residents), within an 18-month period in 2008-2009.

RESULTS

In total, 372 patients with stroke (n = 194), TIA (n = 157) or amaurosis fugax (n = 21) were referred for DUS. We identified 12 patients with 50-70% stenosis and 20 patients with >70% stenosis. Six had CEA, all of whom had stenosis >70%. Waiting time from symptom to CEA was a median of 38 days. Costs of preventing 1 recurrent stroke in the study period [number needed to treat (NNT) = 13] was in the range of EUR 207,675-333,918. If CEA had been performed within 2 weeks after onset of symptoms (NNT = 4), costs would be in the range of EUR 63,900-102,744.

CONCLUSION

Costs of preventing stroke by CEA were high. Substantial reductions of costs (by about 2/3) can be achieved if CEA is performed <2 weeks after the ischemic event.

CT angiography is cost-effective for confirmation of internal carotid artery occlusions

BACKGROUND AND PURPOSE

While sensitive to internal carotid artery (ICA) occlusion, carotid ultrasound can produce false-positive results. CT angiography (CTA) has a high specificity for ICA occlusion and is safer and cheaper than catheter angiography, although less accurate. We determined the cost-effectiveness of CTA versus catheter angiography for confirming an ICA occlusion first suggested by carotid ultrasound.

METHODS

A Markov decision-analytic model was constructed to estimate the cost-effectiveness of CTA compared with catheter angiography in a hypothetical cohort of symptomatic patients with a screening examination consistent with an ICA occlusion. Costs in 2004 dollars were estimated from Medicare reimbursement. Effectiveness was measured in quality-adjusted life years.

RESULTS

The 2-year cost in the CTA scenario was $9,178, and for catheter angiography, $11,531, consistent with a $2,353 cost-savings per person for CTA. CTA resulted in accrual of 1.83 quality-adjusted life years while catheter angiography resulted in 1.82 quality-adjusted life years. CTA was less costly and marginally more effective than catheter angiography. In sensitivity analyses, when CTA sensitivity and specificity were allowed to vary across a plausible range, CTA remained cost-effective.

CONCLUSIONS

After screening examination has suggested an ICA occlusion, confirmatory testing with CTA provides similar effectiveness to catheter angiography and is less costly.

Diagnosis and invasive management of carotid atherosclerotic stenosis

Carotid atherosclerotic stenosis is a known risk factor for ischemic stroke. Methods for detecting stenosis and revascularization abound. The objective of this review was to summarize the evidence for diagnosing carotid artery stenosis and treating symptomatic or asymptomatic stenosis with endarterectomy or stenting. An Ovid MEDLINE search identified relevant original research published between 1990 and 2006. With acceptable surgical risk and patient life expectancy, carotid endarterectomy is clearly indicated for symptomatic stenosis of more than 70%. Carotid endarterectomy is also recommended for symptomatic stenosis of more than 50%, but the health impact is less compelling. The US Food and Drug Administration has approved several stents for a subset of patients with carotid stenosis. Randomized comparisons of endarterectomy vs stenting have been performed in average- and high-risk patients with asymptomatic and symptomatic carotid artery stenosis with mixed results.

The hospital costs of treating necrotizing fasciitis

BACKGROUND

Management of necrotizing fasciitis places significant demands upon hospital and medical resources. A successful management usually requires extensive surgical intervention and an adjunct hyperbaric oxygen treatment. The cost impact on the health care system has not been well characterized. We have, therefore, analysed the cost of treating this disease at an Australian tertiary referral hospital with extensive case experience and well-developed financial costing systems and have compared this with the current casemix-based government funding arrangements applying in Victoria, Australia.

METHODS

Data was extracted from the medical records of 92 sequential patients treated by the Alfred Hospital (Melbourne, Australia) during the four financial years 2000-04. Clinical costing data and government funding data was provided by the hospital's Finance Departments.

RESULTS

The total Alfred Hospital in-patient costs for treating the patients was $5,935,545 with a mean cost per patient of $64,517 (range, $1025 to $514,889). The total casemix-based funding allocation derived from treating these patients was calculated at $3,208,664 with the per patient mean $34,887 (range, $1331 to $387,168). This analysis does not include allowance for non-Alfred Hospital costs such as those incurred by the ambulance service, referring hospitals, for rehabilitation or as a result of the burden of residual disability.

CONCLUSIONS

This study has confirmed that a significant economic burden is involved in treating necrotizing fasciitis. There is a substantial difference between the hospital costs and government funding for treating these patients in the Australian setting.

Cost-effectiveness of diagnostic strategies prior to carotid endarterectomy

The main objective of this study was to assess the long-term cost-effectiveness of five alternative diagnostic strategies for identification of severe carotid stenosis in recently symptomatic patients. A decision-analytical model with Markov transition states was constructed. Data sources included a prospective study involving 167 patients who had screening Doppler ultrasound (DUS), confirmatory contrast-enhanced magnetic resonance angiography (CEMRA) and confirmatory digital subtraction angiography (DSA), individual patient data from the European Carotid Surgery Trial and other published clinical and cost data. A "selective" strategy, whereby all patients receive DUS and CEMRA (only proceeding to DSA if the CEMRA is positive and the DUS is negative), was most cost-effective. This was both the cheapest imaging and treatment strategy (35,205 dollars per patient) and yielded 6.1590 quality-adjusted life years (QALYs), higher than three alternative imaging strategies. Probabilistic sensitivity analysis demonstrated that there was less than a 10% probability that imaging with either DUS or DSA alone are cost-effective at the conventional 50,000 dollars/QALY threshold. In conclusion, DSA is not cost-effective in the routine diagnostic workup of most patients. DUS, with additional imaging in the form of CEMRA, is recommended, with a strategy of "CEMRA and selective DUS review" being shown to be the optimal imaging strategy.

Cost-effectiveness of Intraoperative Imaging in Carotid Endarterectomy

OBJECTIVE:

There has never been a large, randomized controlled trial to assess the impact of intraoperative imaging on the success of carotid endarterectomy (CEA). This comparison involves cost-effectiveness analysis.

METHODS:

We constructed a decision-analytic model to compare effectiveness and costs of intraoperative ultrasound (IUS) and completion angiography as adjuncts to CEA. Data on procedural mortality, morbidity, and costs were obtained from the English-language literature. The review included a total of 52 reports, encompassing more than 22,000 patients. The main components of costs were those of the monitoring interventions and the care of perioperative stroke.

RESULTS:

Mean perioperative outcome without completion imaging is approximately 96.7% of what it would be in the absence of perioperative stroke or death. IUS and completion angiography each result in approximately 2% improvement in expected outcome. Mean perioperative costs are $396.50 for IUS, $721.30 for no monitoring, and $840.90 for completion angiography. Because IUS is significantly more effective at detecting technical errors that would likely result in perioperative stroke than no imaging and is significantly less costly than angiography, this strategy dominates the other two (i.e., it provides greater effectiveness at lower cost).

CONCLUSION:

Although surgical complications are uncommon, IUS substantially lowers the rate of perioperative stroke and mortality and thus is significantly more cost-effective than either completion angiography or no operative imaging.

A maternity hospital-based infant car-restraint loan scheme: public health and economic evaluation of an intervention for the reduction of road traffic injuries

AIMS

The results of an infant car-restraint loan scheme and evaluate its cost-effectiveness are presented.

METHODS

The intervention programme was initiated in 1996. Car-restraints, donated by manufacturers, were lent for a six-month period to eligible prospective parents for a modest fee. Specially trained health visitors performed in-person interviews with the participating parents. The data were collected and recorded on a pre-coded questionnaire. Cross-tabulations and multiple logistic regression were performed to analyse the data. Subsequent purchase of a next-stage car restraint, suitable for older children (up to four years of age) was considered as a proxy measure of the success of the programme. This information, along with the detailed operational and financial data collected during the implementation phase of the programme, was used to develop a model to assess the cost-effectiveness of a countrywide intervention.

RESULTS

During a two-year period 188 families participated in a survey. On return of the infant car restraint, 92% of the participants reported proper use of the device and 82% had already purchased the second-stage car restraint. Parental age, gender, or educational status was not predictive of positive parental road safety practices for the newly born, whereas history of parental seat-belt use--as a proxy of personal road safety behaviour--was positively correlated with the likelihood of purchasing a second-stage car-restraint device. The cost-effectiveness ratio varies between 418.00 euro and 3,225.00 euro per life-year saved, depending on whether the modest administrative fee is considered.

CONCLUSIONS

On the basis of plausible assumptions, a loan programme of infant car-restraints was shown to be particularly cost effective.