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Published online before print June 20, 2007, 10.1148/radiol.2442060713
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(Radiology 2007;244:505-513.)
© RSNA, 2007

Health Policy and Practice

Renal Artery Stenosis: Cost-effectiveness of Diagnosis and Treatment1

Debby van Helvoort-Postulart, PhD, Carmen D. Dirksen, PhD, Patricia J. Nelemans, MD, PhD, Abraham A. Kroon, MD, PhD, Alfons G. H. Kessels, MD, Peter W. de Leeuw, MD, PhD, G. Boudewijn C. Vasbinder, MD, PhD, Jos M. A. van Engelshoven, MD, PhD, and M. G. Myriam Hunink, MD, PhD

1 From the Departments of Clinical Epidemiology and Medical Technology Assessment (D.v.H., C.D.D., A.G.H.K.), Internal Medicine (A.A.K., P.W.d.L.), and Radiology (G.B.C.V., J.M.A.v.E.), University Hospital Maastricht, P Debyelaan 25, 6229 HX Maastricht, the Netherlands; Department of Epidemiology, University of Maastricht, Maastricht, the Netherlands (P.J.N.); Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands (A.A.K., P.W.d.L., J.M.A.v.E.); Departments of Epidemiology and Biostatistics, and Radiology, Erasmus Medical Center, Rotterdam, the Netherlands (M.G.M.H.); and Department of Health Policy and Management, Harvard School of Public Health, Boston, Mass (M.G.M.H.). Received April 24, 2006; revision requested June 23; revision received September 11; accepted October 12; final version accepted December 4. Supported by the Dutch Health Care Insurance Board (grant OG 97-003). Address correspondence to D.v.H. (e-mail: debby.van.helvoort{at}home.nl).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
Purpose: To use a decision analytic model to determine the cost-effectiveness of performing diagnostic digital subtraction angiography (DSA), computed tomographic (CT) angiography, or magnetic resonance (MR) angiography or proceeding immediately to tentative percutaneous revascularization in patients suspected of having renovascular hypertension.

Materials and Methods: With use of a Markov–Monte Carlo decision model, cost-effectiveness analysis was performed from a societal perspective. Data were derived from the Renal Artery Diagnostic Imaging Study in Hypertension and from published literature. The base-case analyses were used to evaluate a 50-year-old patient with a diastolic blood pressure higher than 95 mm Hg and one or more clinical clues suggestive of renovascular hypertension. Outcome measures were quality-adjusted life-year (QALY), lifetime costs, and incremental cost-effectiveness.

Results: For a 50-year-old male patient, immediate tentative revascularization was the least costly ({euro}54 415) and most effective (12.265 QALYs) strategy. For the other strategies, costs and QALYs, respectively, were {euro}55 570 and 12.195 for DSA, {euro}55 191 and 12.163 for CT angiography, and {euro}56 890 and 12.088 for MR angiography. For a 50-year-old female patient, costs and QALYs, respectively, were {euro}66 731 and 13.731 for MR angiography, {euro}63 970 and 13.749 for CT angiography, and {euro}63 079 and 13.902 for DSA. Immediate tentative revascularization yielded more QALYs (13.937) and was more costly ({euro}63 329) than DSA. The incremental cost-effectiveness ratio was {euro}7143 per QALY. As the prior probability increased, use of a more invasive diagnostic imaging strategy became justified. Also, the sensitivities of CT angiography and MR angiography and the costs of DSA influenced the results.

Conclusion: Given currently accepted incremental cost-effectiveness ratios, immediate tentative percutaneous revascularization is a cost-effective strategy for the diagnosis of renal artery stenosis. Management decisions should be conditional on the prior probability.

Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/2442060713/DC1

© RSNA, 2007


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
Digital subtraction angiography (DSA) is considered the reference test for detecting renal artery stenosis. The major disadvantage of DSA is the associated risk of death (1,2) and morbidity, such as arterial dissection (2,3) and renal failure (4–6). At present, minimally invasive imaging techniques such as magnetic resonance (MR) angiography and computed tomographic (CT) angiography are available for the diagnostic work-up of renal artery stenosis. The optimal diagnostic imaging strategy, however, has not yet been defined.

The Renal Artery Diagnostic Imaging Study in Hypertension (RADISH) was performed in the Netherlands to determine the validity of MR angiography and CT angiography, as compared with DSA, in patients suspected of having renovascular hypertension (7). A second goal of the RADISH study was to investigate the cost-effectiveness of CT angiography and MR angiography, as compared with DSA, in the detection of renal artery stenosis. Cost-effective CT angiography and MR angiography examinations could lead to cost savings and fewer complications during the diagnostic work-up. These advantages, however, need to be weighed against the long-term health effects that result from missed diagnoses of renal artery stenosis. Thus, the purpose of our study was to use a decision analytic model to determine the cost-effectiveness of performing diagnostic DSA, CT angiography, or MR angiography or proceeding immediately to tentative percutaneous revascularization in patients suspected of having renovascular hypertension.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
The Model
A Markov–Monte Carlo decision analytic model was developed to calculate the lifetime costs and benefits, expressed in quality-adjusted life-years (QALYs), and the incremental cost-effectiveness ratios (ICERs) associated with five diagnostic strategies for patients suspected of having renovascular hypertension: (a) DSA, (b) CT angiography, (c) MR angiography, (d) immediate tentative percutaneous revascularization, and (e) medical therapy (ie, antihypertension medication), which served as the reference strategy (Fig 1).


Figure 1
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  		Figure 1: Schematic representation of the structure of the decision model. CTA = CT angiography, FN = false-negative result, FP = false-positive result, M = Markov model, MRA = MR angiography, REVAs = immediate tentative revascularization, TN = true-negative result, TP = true-positive result. The reference strategy consists of treatment with antihypertension medication (ie, medical therapy) without imaging work-up. In the DSA strategy, the diagnostic DSA examination and subsequent revascularization are performed during separate sessions; thus, an additional intraarterial procedure is required. Inappropriate treatment indicates that the revascularization procedure was terminated after the diagnostic DSA examination, which was part of the revascularization protocol.

 
In the DSA strategy, diagnostic DSA and subsequent revascularization were performed on different days, so patients with DSA-depicted renal artery stenosis required an additional intraarterial procedure. In the minimally invasive diagnostic imaging strategies—CT angiography and MR angiography—a revascularization procedure was scheduled if CT angiography or MR angiography depicted stenosis, whereas after a negative CT angiography or MR angiography result, no further diagnostic tests were performed immediately. In the immediate tentative revascularization strategy, every patient suspected of having renal artery stenosis was referred for percutaneous revascularization. The results of the diagnostic DSA examination immediately preceding the revascularization procedure were used to determine whether the revascularization would actually be performed. A planned revascularization procedure that was terminated after diagnostic DSA implied inefficient use of personnel, equipment, and room time and thus led to increased costs. In the medical therapy strategy, patients were not referred for diagnostic imaging work-up for renal artery stenosis. Thus, the patency of the renal arteries remained uncertain and percutaneous revascularization was not a treatment option. The analyses were performed from a societal perspective. The model was programmed in DATA Professional (release 11; TreeAge Software, Williamstown, Mass).

Suspicion of renovascular hypertension was based on a diastolic blood pressure of 95 mm Hg or higher and one or more clinical signs suggestive of renovascular hypertension (8) (Appendix E1, Table E1; http://radiology.rsnajnls.org/cgi/content/full/2442060713/DC1). The angiographic definition of hemodynamically significant renal artery stenosis used was stenosis of 50% or greater (9–11), which is the most widely used definition of stenosis (12). After being tested, patients with a negative result, including those with a missed diagnosis of renal artery stenosis and those who were correctly identified as not having stenosis, were treated with antihypertension medication. Patients with a positive result and ostial atherosclerotic stenosis were treated with primary stent placement, whereas those with fibromuscular dysplasia were treated with percutaneous transluminal renal angioplasty. Nonostial atherosclerotic stenoses were treated with percutaneous transluminal renal angioplasty, which if unsuccessful was followed by immediate stent placement.

Major complications resulting from the diagnostic procedures or revascularization were considered to be complications that required therapy and/or prolonged the patient's hospital stay. Two irreversible procedure-related complications were included in this model: chronic renal failure and major stroke. Inherent to decision modeling, various assumptions were necessary to keep the model manageable (Appendix E1, Table E2; http://radiology.rsnajnls.org/cgi/content/full/2442060713/DC1).

Clinical Data and Sensitivity Analyses
A number of variables, base-case values, and ranges were assessed and used in the sensitivity analyses (Appendix E1, Table E3; http://radiology.rsnajnls.org/cgi/content/full/2442060713/DC1) (11–17). Several follow-up data items were also included (Appendix E1, Table E4; http://radiology.rsnajnls.org/cgi/content/full/2442060713/DC1) (18–24). The model combined data from the medical literature with original patient data from the RADISH study (Appendix E1, Table E5; http://radiology.rsnajnls.org/cgi/content/full/2442060713/DC1).

Diagnostic Work-up and Treatment
The prior probability of renal artery stenosis, the percentage of patients presenting with symptoms of fibromuscular dysplasia versus atherosclerosis, and the percentage of ostial versus nonostial lesions were derived from the RADISH study (7). At initial work-up, the prior probability was 19.1% for male patients and 20.9% for female patients (Appendix E1, Table E3; http://radiology.rsnajnls.org/cgi/content/full/2442060713/DC1). The overall prevalence of stenosis in the RADISH study was 20%, which is in line with data in the large Dutch study performed by Krijnen et al (25). If a repeat diagnostic work-up was necessary during follow-up, the estimated probability of recurrent stenosis was 30% for patients who had undergone a prior revascularization procedure for renal artery stenosis, and the estimated probability of developing renal artery stenosis during follow-up was 2% for patients without stenosis at initial work-up (A.A.K., oral personal communication, 2001). DSA was considered the reference test for diagnosing renal artery stenosis. We assumed that there was no loss in the accuracy of DSA data interpretation when this examination was performed in conjunction with preparations for revascularization rather than as a separate procedure. In the cost-effectiveness analysis, data on the diagnostic accuracy of three-dimensional contrast material–enhanced MR angiography from the RADISH study were used (7).

Results of percutaneous transluminal renal angioplasty and stent placement depended on the condition underlying the stenosis—that is, atherosclerosis or fibromuscular dysplasia. Treatment results were defined in terms of diastolic blood pressure and renal function, which were referred to as the clinical status of the patient. Data on clinical status during the first year after treatment were derived from the RADISH study, and original patient data were derived from the Dutch Renal Artery Stenosis Intervention Cooperative, or DRASTIC, Study (11). Data on the clinical results beyond 1 year were based on data reported in the literature, adjusted, and supplemented with expert opinion (A.A.K., oral personal communication, 2001). The percentage of major complications from a revascularization procedure (8.8%) was derived from a published review of the findings in 1118 patients (15).

Follow-up Data
The mortality rates for patients with essential hypertension and for patients after treatment for renal artery stenosis, as compared with the mortality rate in the general population, were expressed as annual relative hazard ratios (Appendix E1, Table E4; http://radiology.rsnajnls.org/cgi/content/full/2442060713/DC1) (18). The mortality rates for patients undergoing dialysis were derived from a report on the mortality among patients with hypertension-induced renal failure who were starting dialysis therapy (20). The rate of mortality after stroke was derived from a community-based study on the 5-year survival of patients after a first-ever stroke (19).

Costs and QALYs
The cost calculations (Appendix E1, Table E6; http://radiology.rsnajnls.org/cgi/content/full/2442060713/DC1) (26–35) were performed according to the Dutch guidelines for cost calculations in health care (26). All costs relevant to society were considered. Costs were calculated by multiplying the unit costs by the volumes of use. Time costs included time spent by family and friends in providing informal care and patient time costs due to the inability to perform usual activities, which was approximated on the basis of absence from work and/or inability to perform housekeeping. The costs of informal care and housekeeping were derived by using a shadow price of {euro}8 per hour, the wage rate for a cleaning person (26). Shadow pricing is often used to determine the costs for goods and services for which no market prices exist. Productivity losses were estimated with the friction cost method. With this method, production losses are confined to the period needed to replace a sick worker. The length of this period and the resulting costs depend on the situation in the labor market (36–38).

Unit costs—not charges—for procedures and laboratory tests, including the costs for personnel, materials, and equipment, were available from the University Hospital Maastricht. To take housing and overhead expenses into account, unit costs were increased by 35% (26). For hospitalizations, outpatient visits, home care, travel costs, and general practitioner visits, the unit costs quoted in the Dutch guidelines were used (26). Empiric data on medication use were available from the RADISH study. To determine the costs of medications, the Pharmacotherapeutic Compass 2000/2001 (39) was used; this report provides information about drugs that are available in the Netherlands and their associated unit (defined daily dose) costs. Data on costs outside the health care sector, as well as information about general practitioner visits and home care utilization, were gathered by using cost diaries. Patients with a paid housekeeper were asked to provide information about the associated out-of-pocket expenses. Future health and non–health care costs that were not related to the disease being investigated were not considered. All costs are presented in year 2000 euros ($1 = {euro}1.08, StatLine database of Dutch Bureau of Statistics [http://statline.cbs.nl/]).

QALY was calculated as the sum of the time spent in each health state multiplied by a correction factor representing the quality of life—that is, the utility—in each of the health states. Death resulted in loss of life-years. Health values for patients 1 year after treatment for renal artery stenosis were available from the RADISH study. We assessed quality of life by using the EuroQol-5D instrument (40,41) to derive population time trade-off utilities (42,43). Also, the utilities that were derived from the literature were elicited by using the time trade-off instrument (31–34). Utilities were assumed to remain constant over time within a given health state.

Temporary disutility (dissatisfaction) from diagnostic imaging techniques and percutaneous treatment procedures—for example, disutility due to burdens and complications—was included in the model as a quality-of-life reduction and was measured on a visual analog scale. These values were adjusted for the duration of the discomfort.

Analyses
Markov models assume that a patient is always in one of a finite number of health states. All events are represented as transitions from one state to another. A Monte Carlo evaluation of a Markov model is used to determine the prognoses of a large number of individual patients. The time horizon of the analysis is divided into cycles: Each patient begins in an initial state. During each cycle, the patient may make a transition from one state to another according to the laws of chance, as dictated by the transition probabilities. After the first patient has completed the simulation, another patient begins in the initial state and a new simulation is performed. This process is repeated many times, and each simulation generates a quality-adjusted survival time and costs.

Monte Carlo analysis, as opposed to a Markov cohort model without memory, offers the possibility to flag subjects to track their characteristics and disease histories, which is a flexible approach to modeling variability within a population. The base-case analyses were used to evaluate a 50-year-old male patient and 50-year-old female patient with a diastolic blood pressure higher than 95 mm Hg and one or more clinical signs suggestive of renovascular hypertension (8). With use of first-order Monte Carlo analysis, these patients were simulated multiple times (n = 50 000 trials) for each of the five strategies. The decision to examine 50-year-old patients was based on the mean age of the patients enrolled in the RADISH study. In addition, a 60-year-old male patient and 40-year-old female patient were considered. Life expectancies were 28 and 32 years for the 50-year-old male and female patients, respectively, and 20 and 42 years for the 60-year-old male and 40-year-old female patients, respectively (StatLine Dutch Bureau of Statistics, November 2003). Sensitivity analyses were performed to examine the robustness of the results—that is, the extent to which varying variable values influence ICERs.

Future costs and benefits were discounted at an annual rate of 3% (17). To determine the cost-effectiveness of alternative diagnostic strategies, ICERs were calculated. The strategies were ordered according to increasing effectiveness, and (extended) dominated strategies were eliminated. A strategy was considered to be dominated by another strategy if the latter yielded more QALYs at lower costs. A strategy was considered to be extended dominated if another strategy yielded more QALYs and had a lower ICER. ICERs for the remaining strategies were then calculated as the difference in costs divided by the difference in QALYs for one particular strategy compared with the next best strategy.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
Base-Case Analyses
For a 50-year-old male patient, immediate tentative revascularization, the strategy whereby a revascularization procedure was planned for every patient suspected of having renal artery stenosis, was the least costly and most effective: It dominated all other strategies (Table 1, Fig 2). For a 50-year-old female patient, the immediate tentative revascularization strategy was more effective than the DSA strategy, but it was also more costly and had an ICER of {euro}7143 per QALY. For a 60-year-old male patient, the dominance-based order of the strategies did not change: Immediate tentative revascularization dominated all other strategies, with a cost of {euro}38 783 and an effectiveness of 8.744 QALYs. For a 40-year-old female patient, the immediate revascularization strategy was the most effective (16.668 QALYs) and least costly ({euro}75 734), and it dominated all other strategies.


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  		Table 1. Results for a Hypothetical 50-Year-Old Patient Suspected of Having Renal Artery Stenosis

 

Figure 2A
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  		Figure 2a: Graphs illustrate QALYs versus costs for (a) male and (b) female patients. x = medical therapy, {blacktriangledown} = MR angiography, {blacksquare} = CT angiography, bullet = DSA, + = immediate tentative revascularization.

 

Figure 2B
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  		Figure 2b: Graphs illustrate QALYs versus costs for (a) male and (b) female patients. x = medical therapy, {blacktriangledown} = MR angiography, {blacksquare} = CT angiography, bullet = DSA, + = immediate tentative revascularization.

 
Sensitivity Analyses
For male patients, the results were influenced by the prior probability of renal artery stenosis and the sensitivity values for MR angiography and CT angiography (Table 2). If the prior probability was more than 11%, immediate tentative revascularization dominated all other strategies. If the sensitivity of MR angiography ranged from 88% to 94%, immediate tentative revascularization dominated all other strategies. Beyond 95% sensitivity, immediate tentative revascularization was more effective than MR angiography but also more costly; however, the ICER ({euro}6379) was still attractive—even when MR angiography was 100% sensitive. When the model was recalculated with the assumption of 98% sensitivity for both CT angiography and MR angiography, the ICER for immediate tentative revascularization compared with CT angiography was {euro}39 969 per QALY. Results were robust when the other variables were varied: Immediate tentative revascularization remained dominant.


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  		Table 2. Sensitivity Analysis Results for Male Patients

 
For female patients, the results were influenced by the prior probability of renal artery stenosis, the sensitivity of MR angiography and CT angiography, and the costs of DSA (Table 3). If the prior probability was more than 29%, immediate tentative revascularization dominated all other strategies. If the sensitivity of MR angiography was 99% or greater, MR angiography dominated all other strategies. When the model was recalculated with the assumption of 98% sensitivity for both CT angiography and MR angiography, the ICER for MR angiography compared with CT angiography was {euro}19 100 per QALY. For the base-case analyses, it was assumed that patients were admitted to the hospital for 2 nights for DSA ({euro}1711). In cases of admission for 3 nights ({euro}2063), immediate tentative revascularization dominated all other strategies. Results were robust when the other variables were varied: The ICER for immediate tentative revascularization compared with DSA ranged from {euro}4409 to {euro}9057 per QALY.


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  		Table 3. Sensitivity Analysis Results for Female Patients

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 
Our study results show that for male patients, immediate tentative revascularization dominated all other strategies, proving to be cost-effective. This means that every male patient suspected of having renal artery stenosis should be scheduled for a revascularization procedure. Results of the diagnostic DSA examination immediately preceding the revascularization procedure are used to determine whether or not to proceed to the revascularization. For female patients, the ICER for immediate tentative revascularization compared with DSA was {euro}7143 per QALY, which is generally considered an acceptable incremental cost relative to the effectiveness gained.

Our findings may be explained by the poor sensitivity of CT angiography and MR angiography. The model included sensitivity data from the RADISH study: 69% sensitivity for CT angiography and 57% sensitivity for MR angiography. Since these unfavorable sensitivity values were contrary to the results of nearly all other published studies on the validity of CT angiography and MR angiography (12), the model was recalculated with the assumption of excellent sensitivity for CT angiography and MR angiography and demonstrated a potential role for CT angiography and MR angiography in the diagnostic work-up of hypertensive patients suspected of having renal artery stenosis.

Investigators in seven previously published studies analyzed the cost-effectiveness of the diagnostic work-up for renal artery stenosis (44–50). The studies differed from our analysis in terms of the outcome measures (cost per successful treatment, cost per life-year gained), type of imaging techniques included in the evaluation, time frame considered, sensitivity and specificity values, and perspective of the analysis. Because of differences between the studies, it was difficult to compare our results with those reported in the literature and to draw general conclusions about the optimal diagnostic work-up strategy for renal artery stenosis.

Nelemans et al (45) assessed the cost-effectiveness of eight diagnostic strategies used to diagnose renovasular hypertension. The analysis was conducted from the perspective of the health care system, the outcome measure was costs per life-year gained, and the time frame considered was 10 years. The authors found that performing CT angiography before angiography maximized the number of additional life-years saved and was a cost-effective alternative to performing captopril renography before angiography. Direct angiography was dominated and thus inferior. Furthermore, strategies involving MR angiography were cost-effective only when the costs of this examination could be halved.

Carlos et al (50) evaluated the cost-effectiveness of conventional angiography (99% sensitivity and specificity), CT angiography (96% sensitivity and specificity), and MR angiography (98% sensitivity, 94% specificity). The imaging strategies were compared with the natural history of medication-resistant hypertension (ie, two-drug therapy) and with enhanced medical therapy (ie, a third antihypertensive medication was prescribed) without prior imaging. Immediate tentative revascularization was not analyzed. The analysis was performed from a societal perspective and used to assess lifetime costs and QALYs. The three imaging strategies and enhanced medical therapy dominated natural history. Conventional angiography dominated CT angiography, MR angiography, and enhanced medical therapy; these results are consistent with our findings.

Our study had limitations: First, various assumptions regarding the data had to be made. For example, the clinical treatment results were derived from the RADISH study and the Dutch Renal Artery Stenosis Intervention Cooperative Study (11). The clinical results after treatment and at 1 year were used to calculate the conditional probabilities for the first year of follow-up. Since the follow-up period after treatment for renal artery stenosis was limited to 12 months, it was impossible to empirically determine the long-term clinical results. Furthermore, the decision model required conditional probabilities. Published studies commonly do not provide sufficient detail to derive this information, and often the reported numbers are not fully applicable to the problem being investigated.

A second limitation was the unclear extent to which our cost-effectiveness analysis results were generalizable to other countries, given the differences in availability of health care resources, clinical practice, incentives to health care professionals and institutions, and relative prices and costs. Visser et al (51) calculated higher ICERs for the United States than for the Netherlands. However, the practical implications for the clinical problem being investigated—that is, the management strategies for patients with intermittent claudication—were the same. The authors made use of the threshold ICERs that are considered acceptable in both countries. In the Netherlands, threshold ICERs range from {euro}33 000 to {euro}54 000 per QALY (52,53), and in the United States, the generally reported ICERs vary between $10 000 and $100 000 per QALY (54). Although we did not compare data from the United States with data from the Netherlands, applying these values to our study would lead to the same conclusions regarding the cost-effectiveness of diagnostic imaging strategies to detect renal artery stenosis in both countries. Although the results of other studies are also encouraging (35,55,56), it should be noted that the generalization of cost-effectiveness results across countries might not be applicable for other clinical problems.

Clinical practices vary considerably across hospitals and physicians, even if the patient populations are considered similar, and to date, the clinical algorithm for the diagnostic imaging work-up of patients suspected of having renovascular hypertension is not clearly defined. Our study results show that diagnostic imaging testing for renal artery stenosis appears to be justified, even in a population of patients with hypertension and a relatively low prevalence of renal artery stenosis. Furthermore, the decision of which diagnostic strategy to use depends on the probability of renal artery stenosis and the threshold ICER that is considered acceptable. As the prior probability increases, a more invasive diagnostic imaging strategy becomes justified. Therefore, for each patient, a clinical prediction rule should be used to calculate the probability that renal artery stenosis is present (25).

In conclusion, our study results suggest that (a) immediate tentative revascularization is cost-effective in patients highly suspected of having renovascular hypertension, (b) CT angiography is cost-effective in patients for whom there is low suspicion, and (c) medical therapy is cost-effective in patients in whom renal artery stenosis is unlikely.


   ADVANCES IN KNOWLEDGE
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
IMPLICATION FOR PATIENT CARE
 References
 


   IMPLICATION FOR PATIENT CARE
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
References
 


   FOOTNOTES
 

Abbreviations: DSA = digital subtraction angiography • ICER = incremental cost-effectiveness ratio • QALY = quality-adjusted life-year • RADISH = Renal Artery Diagnostic Imaging Study in Hypertension

Authors stated no financial relationship to disclose.

Author contributions: Guarantors of integrity of entire study, D.v.H., C.D.D., P.W.d.L., J.M.A.v.E., M.G.M.H.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, D.v.H., P.J.N., A.A.K., P.W.d.L., G.B.C.V., J.M.A.v.E.; clinical studies, P.J.N., A.A.K., A.G.H.K., P.W.d.L., G.B.C.V., J.M.A.v.E.; statistical analysis, D.v.H., C.D.D., A.A.K., A.G.H.K., P.W.d.L., M.G.M.H.; and manuscript editing, all authors


   References
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 IMPLICATION FOR PATIENT CARE
 References
 

  1. Hessel SJ, Adams DF, Abrams HL. Complications of angiography. Radiology 1981;138:273–281.[Abstract/Free Full Text]
  2. Waugh JR, Sacharias N. Arteriographic complications in the DSA era. Radiology 1992;182:243–246.[Abstract/Free Full Text]
  3. Young N, Chi KK, Ajaka J, McKay L, O'Neill D, Wong KP. Complications with outpatient angiography and interventional procedures. Cardiovasc Intervent Radiol 2002;25:123–126.[CrossRef][Medline]
  4. Rudnick MR, Berns JS, Cohen RM, Goldfarb S. Nephrotoxic risks of renal angiography: contrast media-associated nephrotoxicity and atheroembolism—a critical review. Am J Kidney Dis 1994;24:713–727.[Medline]
  5. Cochran ST, Bomyea K, Sayre JW. Trends in adverse events after IV administration of contrast media. AJR Am J Roentgenol 2001;176:1385–1388.[Abstract/Free Full Text]
  6. Thomsen HS, Morcos SK; and Members of Contrast Media Safety Committee of European Society of Urogenital Radiology (ESUR). In which patients should serum creatinine be measured before iodinated contrast medium administration? Eur Radiol 2005;15:749–754.[CrossRef][Medline]
  7. Vasbinder GB, Nelemans PJ, Kessels AG, et al. Accuracy of computed tomographic angiography and magnetic resonance angiography for diagnosing renal artery stenosis. Ann Intern Med 2004;141:674–682.[Abstract/Free Full Text]
  8. Working Group on Renovascular Hypertension. Detection, evaluation, and treatment of renovascular hypertension: final report. Arch Intern Med 1987;147:820–829.[Abstract]
  9. Webster J, Marshall F, Abdalla M, et al; and the Scottish and Newcastle Renal Artery Stenosis Collaborative Group. Randomised comparison of percutaneous angioplasty vs continued medical therapy for hypertensive patients with atheromatous renal artery stenosis. J Hum Hypertens 1998;12:329–335.
  10. van de Ven PJ, Kaatee R, Beutler JJ, et al. Arterial stenting and balloon angioplasty in ostial atherosclerotic renovascular disease: a randomised trial. Lancet 1999;353:282–286.[CrossRef][Medline]
  11. van Jaarsveld BC, Krijnen P, Pieterman H, et al; and the Dutch Renal Artery Stenosis Intervention Cooperative Study Group. The effect of balloon angioplasty on hypertension in atherosclerotic renal-artery stenosis. N Engl J Med 2000;342:1007–1014.
  12. Vasbinder GB, Nelemans PJ, Kessels AG, Kroon AA, de Leeuw PW, van Engelshoven JM. Diagnostic tests for renal artery stenosis in patients suspected of having renovascular hypertension: a meta-analysis. Ann Intern Med 2001;135:401–411.[Abstract/Free Full Text]
  13. Lawrence V, Matthai W, Hartmaier S. Comparative safety of high-osmolality and low-osmolality radiographic contrast agents. Invest Radiol 1992;27:2–28.[CrossRef][Medline]
  14. Weibull H, Bergqvist D, Jonsson K, Carlsson S, Takolander R. Analysis of complications after percutaneous transluminal angioplasty of renal artery stenoses. Eur J Vasc Surg 1987;1:77–84.[CrossRef][Medline]
  15. Martin LG, Rees CR, O'Bryant T. Percutaneous angioplasty of the renal arteries. In: Strandness DE, Breda van A, eds. Vascular diseases: surgical and interventional therapy. 3rd ed. New York, NY: Churchill Livingstone, 1994;721–741.
  16. Leertouwer TC, Gussenhoven EJ, Bosch JL, et al. Stent placement for renal arterial stenosis: where do we stand? a meta-analysis. Radiology 2000;216:78–85.
  17. Gold MR, Siegel JE, Russel LB, Weinstein MC. Cost-effectiveness in health and medicine. New York, NY: Oxford University Press, 1996;
  18. Isles C, Main J, O'Connell J, et al. Survival associated with renovascular disease in Glasgow and Newcastle: a collaborative study. Scott Med J 1990;35:70–73.[Medline]
  19. Hankey GJ, Jamrozik K, Broadhurst RJ, et al. Five-year survival after first-ever stroke and related prognostic factors in the Perth Community Stroke Study. Stroke 2000;31:2080–2086.[Abstract/Free Full Text]
  20. Byrne C, Vernon P, Cohen JJ. Effect of age and diagnosis on survival of older patients beginning chronic dialysis. JAMA 1994;271:34–36.[Abstract]
  21. Iseki K, Kimura Y, Wakugami K, et al. Comparison of the effect of blood pressure on the development of stroke, acute myocardial infarction, and end-stage renal disease. Hypertens Res 2000;23:143–149.[Medline]
  22. Losinno F, Zuccalà A, Busato F, Zucchelli P. Renal artery angioplasty for renovascular hypertension and preservation of renal function: long-term angiographic and clinical follow-up. AJR Am J Roentgenol 1994;162:853–857.[Abstract/Free Full Text]
  23. Chabova V, Schirger A, Stanson AW, McKusick MA, Textor SC. Outcomes of atherosclerotic renal artery stenosis managed without revascularization. Mayo Clin Proc 2000;75:437–444.[Medline]
  24. MacMahon S, Peto R, Cutler J, et al. Blood pressure, stroke, and coronary heart disease. I. Prolonged differences in blood pressure: prospective observational studies corrected for the regression dilution bias. Lancet 1990;335:765–774.[CrossRef][Medline]
  25. Krijnen P, van Jaarsveld BC, Steyerberg EW, Man in `t Veld AJ, Schalekamp MA, Habbema JD. A clinical prediction rule for renal artery stenosis. Ann Intern Med 1998;129:705–711.[Abstract/Free Full Text]
  26. Oostenbrink JB, Koopmanschap MA, Rutten FF. Handleiding voor kostenonderzoek: methoden en richtlijnprijzen voor economische evaluaties in de gezondheidszorg. Amstelveen, the Netherlands: College voor zorgverzekeringen, 2000;
  27. de Wit GA, Polder JJ, Jager KJ, de Charro FT. De maatschappelijke kosten van nierziekten in Nederland. Tijdschr Gezondheidswetenschappen 2001;79:49–54.
  28. van Bergen PF, Jonker JJ, van Hout BA, et al. Costs and effects of long-term oral anticoagulant treatment after myocardial infarction. JAMA 1995;273:925–928.[Abstract]
  29. Bergman L, van der Meulen JH, Limburg M, Habbema JD. Costs of medical care after first-ever stroke in the Netherlands. Stroke 1995;26:1830–1836.[Abstract/Free Full Text]
  30. Kiiskinen U, Vartiainen E, Puska P, Aromaa A. Long-term cost and life-expectancy consequences of hypertension. J Hypertens 1998;16:1103–1112.[CrossRef][Medline]
  31. Samsa GP, Matchar DB, Goldstein L, et al. Utilities for major stroke: results from a survey of preferences among persons at increased risk for stroke. Am Heart J 1998;136:703–713.[CrossRef][Medline]
  32. Postulart D, Adang EM. Response shift and adaptation in chronically ill patients. Med Decis Making 2000;20:186–193.[Abstract/Free Full Text]
  33. Tsevat J, Goldman L, Lamas GA, et al. Functional status versus utilities in survivors of myocardial infarction. Med Care 1991;29:1153–1159.[CrossRef][Medline]
  34. Lawrence WF, Fryback DG, Martin PA, Klein R, Klein BE. Health status and hypertension: a population-based study. J Clin Epidemiol 1996;49:1239–1245.[CrossRef][Medline]
  35. Bosch JL, Tetteroo E, Mali WP, Hunink MG; for the Dutch Iliac Stent Trial Study Group. Iliac arterial occlusive disease: cost-effectiveness analysis of stent placement versus percutaneous transluminal angioplasty. Radiology 1998;208:641–648.[Abstract/Free Full Text]
  36. Koopmanschap MA, van Ineveld BM. Towards a new approach for estimating indirect costs of disease. Soc Sci Med 1992;34:1005–1010.[CrossRef][Medline]
  37. Koopmanschap MA, Rutten FF, van Ineveld BM, van Roijen L. The friction cost method for measuring indirect costs of disease. J Health Econ 1995;14:171–189.[CrossRef][Medline]
  38. Koopmanschap MA, Rutten FF. A practical guide for calculating indirect costs of disease. Pharmacoeconomics 1996;10:460–466.[Medline]
  39. Farmacotherapeutisch Kompas 2000/2001. Amstelveen, the Netherlands: College voor zorgverzekeringen.
  40. The EuroQol Group. EuroQol: a new facility for the measurement of health-related quality of life. Health Policy 1990;16:199–208.[CrossRef][Medline]
  41. Brooks R. EuroQol: the current state of play. Health Policy 1996;37:53–72.[CrossRef][Medline]
  42. Dolan P, Gudex C, Kind P, Williams A. A social tariff for EuroQol: results from a UK general population survey—discussion paper 138. York, United Kingdom: University of York, Centre for Health Economics, 1995;
  43. Dolan P. Modeling valuations for EuroQol health states. Med Care 1997;35:1095–1108.[CrossRef][Medline]
  44. Helin KH, Tikkanen I, Von Knorring JE, et al. Screening for renovascular hypertension in a population with relatively low prevalence. J Hypertens 1998;16:1523–1529.[CrossRef][Medline]
  45. Nelemans PJ, Kessels AG, de Leeuw P, de Haan M, van Engelshoven J. The cost-effectiveness of the diagnosis of renal artery stenosis. Eur J Radiol 1998;27:95–107.[CrossRef][Medline]
  46. Radermacher J, Brunkhorst R. Diagnosis and treatment of renovascular stenosis: a cost-benefit analysis. Nephrol Dial Transplant 1998;13:2761–2767.[Abstract/Free Full Text]
  47. Blaufox MD, Middleton ML, Bongiovanni J, Davis BR. Cost efficacy of the diagnosis and therapy of renovascular hypertension. J Nucl Med 1996;37:171–177.[Abstract/Free Full Text]
  48. Lawrence WF, Grist TM, Brazy PC, Fryback DG. Magnetic resonance angiography in progressive renal failure: a technology assessment. Am J Kidney Dis 1995;25:701–709.[Medline]
  49. Lévesque J, Lacourcière Y, Onrot JM, et al. Economic impact of an ultrasonographic contrast agent on the diagnosis and initial management of patients with suspected renal artery stenosis. Can Assoc Radiol J 2002;53:228–236.[Medline]
  50. Carlos RC, Axelrod DA, Ellis JH, Abrahamse PH, Fendrick AM. Incorporating patient-centered outcomes in the analysis of cost-effectiveness: imaging strategies for renovascular hypertension. AJR Am J Roentgenol 2003;181:1653–1661.[Abstract/Free Full Text]
  51. Visser K, de Vries SO, Kitslaar PJ, van Engelshoven JM, Hunink MG. Cost-effectiveness of diagnostic imaging work-up and treatment for patients with intermittent claudication in the Netherlands. Eur J Vasc Endovasc Surg 2003;25:213–223.[CrossRef][Medline]
  52. van Hout B, Bonsel G, Habbema D, van der Maas P, de Charro F. Heart transplantation in the Netherlands: costs, effects and scenarios. J Health Econ 1993;12:73–93.[CrossRef][Medline]
  53. van Enckevort PJ, TenVergert EM, Bonsel GJ, et al. Technology assessment of the Dutch Lung Transplantation Program. Int J Technol Assess Health Care 1998;14:344–356.[Medline]
  54. Graham JD, Corso PS, Morris JM, Segui-Gomez M, Weinstein MC. Evaluating the cost-effectiveness of clinical and public health measures. Annu Rev Public Health 1998;19:125–152.[CrossRef][Medline]
  55. van Erkel AR, van den Hout WB, Pattynama PM. International differences in health care costs in Europe and the United States: do these affect cost-effectiveness of diagnostic strategies for pulmonary embolism? Eur Radiol 1999;9:1926–1931.[CrossRef][Medline]
  56. Bosch JL, Haaring C, Meyerovitz MF, Cullen KA, Hunink MG. Cost-effectiveness of percutaneous treatment of iliac artery occlusive disease in the United States. AJR Am J Roentgenol 2000;175:517–521.[Abstract/Free Full Text]




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