Cost and patency rate targets for the development of endovascular devices to treat femoropopliteal arterial disease

PURPOSE: To determine the criteria that would make use of an endovascular device cost-effective compared with bypass surgery and percutaneous transluminal angioplasty in the treatment of femoropopliteal arterial disease. MATERIALS AND METHODS: A decision model was developed to compare treatment with the use of a hypothetical endovascular device with established therapies. Cost-effectiveness from the perspective of the health care system was considered. Outcome measures were lifetime costs and quality-adjusted life-years. With the use of net health benefit calculations and threshold analysis, combinations of costs and patency rates were determined that would make the device cost-effective compared with established therapies. In subgroup and sensitivity analyses, the effect on decision-making of sex, age, indication, lesion type, procedural risk, and society's willingness to pay for incremental gain in health were explored. RESULTS: Use of a device that costs $3,000 would be cost-effective compared with bypass surgery for critical ischemia if the 5-year patency rate is 29%-46%. Use of the same device would be cost-effective compared with angioplasty for disabling claudication and stenosis if the 5-year patency rate is 69%-86%. CONCLUSION: The target combinations of costs and patency rates found in this study are probably attainable, and further development of such endovascular devices seems warranted

Study design for concurrent development, assessment, and implementation of new diagnostic imaging technology

With current constraints on health care resources and emphasis on value for money, new diagnostic imaging technologies must be assessed and their value demonstrated. The state of the art in the field of diagnostic imaging technology assessment advocates a hierarchical step-by-step approach. Although rigorous, such a hierarchical assessment is time-consuming, and, given the current rapid advances in technology, results are often too late to influence management and policy decisions. The purpose of this article is to discuss a study design in which development, assessment, and implementation of new diagnostic imaging technology take place concurrently in one integrated process. An empirically based pragmatic study design is proposed for imaging technology assessment. To minimize bias and enable comparison with current technology, a randomized controlled design is used whenever feasible and ethical. Outcome measures should reflect the clinical decision-making process based on imaging information and acceptance of the new test. Outcome measures can include additional imaging studies requested, costs of diagnostic work-up and treatment, physicians' confidence in therapeutic decision making, recruitment rate, and patient outcome measures related to the clinical problem. The key feature of the proposed study design is analysis of trends in outcome measures over time

Peripheral arterial disease: gadolinium-enhanced MR angiography versus color-guided duplex US--a meta-analysis

PURPOSE: To summarize and compare the published data on gadolinium-enhanced magnetic resonance (MR) angiography and color-guided duplex ultrasonography (US) for the work-up for peripheral arterial disease. MATERIALS AND METHODS: Studies published between January 1984 and November 1998 were included if (a) gadolinium-enhanced MR angiography and/or color-guided duplex US were performed for evaluation of arterial stenoses and occlusions in the work-up for peripheral arterial disease of the lower extremities, (b) conventional angiography was the reference standard, and (c) absolute numbers of true-positive, false-negative, true-negative, and false-positive results were available or derivable. RESULTS: With a random effects model, pooled sensitivity for MR angiography (97.5% [95% CI: 95.7%, 99.3%]) was higher than that for duplex US (87.6% [95% CI: 84.4%, 90.8%]). Pooled specificities were similar: 96.2% (95% CI: 94.4%, 97.9%) for MR angiography and 94.7% (95% CI: 93.2%, 96.2%) for duplex US. Summary receiver operating characteristic analysis demonstrated better discriminatory power for MR angiography than for duplex US. Regression coefficients for MR angiography versus US were 1.67 (95% CI: -0.23, 3.56) with adjustment for covariates, 2.11 (95% CI: 0.12, 4.09) without such adjustment, and 1.73 (95% CI: 0.44, 3.02) with a random effects model. CONCLUSION: Gadolinium-enhanced MR angiography has better discriminatory power than does color-guided duplex US and is a highly sensitive and specific method, as compared with conventional angiography, for the work-up for peripheral arterial disease

Applications of decision analysis in diagnostic radiology

The subjects of this thesis are decision analysis and receiver operating characteristic (ROC) methodology applied to radiological problems. This thesis is intended for those interested in applying decision analytical techniques in diagnostic radiology, and in medicine in general. Chapter II deals with the theory of decision trees and Markov processes. The basic concepts are briefly explained and a few selected topics are discussed in more detaiL Chapter III describes a decision model for the diagnostic workup and treatment of renovascular hypertension. Chapter IV presents a Markov analysis of the decision whether, and when, to intervene in acute urinary tract obstruction. Chapter V deals with the theory of receiver operating characteristic (ROC) methodology. Basic concepts are explained and a number of selected issues are discussed in detaiL Chapter VI presents an ROC analysis of the assessment of tumor extension in neoplastic disease of the nose, paranasal sinuses, nasopharynx and parapharyngeal space, comparing computer tomography (CT) and magnetic resonance imaging (MRI). Chapter VII presents the results of an ROC analysis of orbital space-occupying lesions comparing the diagnosis made by means of clinical evaluation, computer tomography (CT) and magnetic resonance imaging (MRI). Chapter VIII presents the results of a study on fetal pulmonary maturity testing, involving a number of interesting methodological issues of ROC analysis. A general discussion follows in chapter IX

From complexity to clarity:how directed acyclic graphs enhance the study design of systematic reviews and meta-analyses

While frameworks to systematically assess bias in systematic reviews and meta-analyses (SRMAs) and frameworks on causal inference are well established, they are less frequently integrated beyond the data analysis stages. This paper proposes the use of Directed Acyclic Graphs (DAGs) in the design stage of SRMAs. We hypothesize that DAGs created and registered a priori can offer a useful approach to more effective and efficient evidence synthesis. DAGs provide a visual representation of the complex assumed relationships between variables within and beyond individual studies prior to data analysis, facilitating discussion among researchers, guiding data analysis, and may lead to more targeted inclusion criteria or set of data extraction items. We illustrate this argument through both experimental and observational case examples.</p

Health-related quality of life after angioplasty and stent placement in patients with iliac artery occlusive disease: results of a randomized controlled clinical trial.

BACKGROUND: To assess the quality of life in patients with iliac artery occlusive disease, we compared primary stent placement versus primary angioplasty followed by selective stent placement in a multicenter randomized controlled trial. METHODS AND RESULTS: Quality-of-life assessments were completed by 254 patients in a telephone interview. Assessment measures consisted of the RAND 36-Item Health Survey 1.0, time tradeoff, standard gamble, rating scale, health utilities index, and EuroQol-5D. The interviews were performed before treatment and after 1, 3, 12, and 24 months. When the 2 treatments were compared, no significant difference was observed (P>0.05). All measurements showed a significant improvement in the quality of life after treatment (P<0.05). The RAND 36-Item Health Survey measures physical functioning, role limitations caused by physical problems, and bodily pain and the EuroQol-5D were the most sensitive to the impact of revascularization. CONCLUSIONS: Health-related quality of life improves equally after primary stent placement and primary angioplasty with selective stent placement in the treatment of intermittent claudication caused by iliac artery occlusive disease

Balloon dilation and stent implantation for treatment of femoropopliteal arterial disease: meta-analysis

PURPOSE: To perform a meta-analysis of long-term results of balloon dilation and stent implantation in the treatment of femoropopliteal arterial disease. MATERIALS AND METHODS: The English-language literature was searched for studies published between 1993 and 2000. Inclusion criteria for articles were presentation of long-term primary patency rates, standard errors (explicitly reported or derivable), and baseline characteristics of the study population. Two reviewers independently extracted data, and discrepancies were resolved by consensus. Primary patency rates were combined by using a technique that allows adjustment for differences across study populations. Analyses were adjusted for lesion type and clinical indication. RESULTS: Nineteen studies met the inclusion criteria, representing 923 balloon dilations and 473 stent implantations. Combined 3-year patency rates after balloon dilation were 61% (standard error, 2.2%) for stenoses and claudication, 48% (standard error, 3.3%) for occlusions and claudication, 43% (standard error, 4.1%) for stenoses and critical ischemia, and 30% (standard error, 3.7%) for occlusions and critical ischemia. The 3-year patency rates after stent implantation were 63%-66% (standard error, 4.1%) and were independent of clinical indication and lesion type. Funnel plots demonstrated an asymmetric distribution of the data points associated with stent studies. CONCLUSION: Balloon dilation and stent implantation for claudication and stenosis yield similar long-term patency rates. For more severe femoropopliteal disease, the results of stent implantation seem more favorable. Publication bias could not be ruled out