Renal Artery Stenosis: Cost-effectiveness of Diagnosis and Treatment

Effectiveness of contrast-enhanced duplex ultrasound for detecting renal artery stenosis: A systematic review

PURPOSE

Contrast-enhanced duplex ultrasound (CEUS) might be a useful tool to diagnosing renal artery stenosis (RAS). We amalgamated and reviewed the evidence assessing the diagnostic accuracy of CEUS on detecting RAS compared to angiography.

METHODS

This preregistered systematic review included studies that compared the presence of RAS via CEUS with angiography. Sources were searched in November 2022 and included Scopus, EMBASE, MEDLINE, CINAHL, and Academic Search Premier (n = 1717). The Quality Assessment of Diagnostic Studies 2 tool assessed study quality. Results are presented narratively.

RESULTS

The studies included (n = 11) had a total of 447 unique participants (193 females) and average age of 56 ± 9 years. Five of eleven studies investigated CEUS using SonoVue contrast agent and reported an average accuracy (91% ± 2%), sensitivity (91% ± 3%), specificity (90% ± 5%), negative predictive value (86% ± 6%), and positive predictive value (94% ± 1%) with all values >80%. The accuracy of CEUS using other types of contrast agent (n = 6), including Levovsit (n = 3/6), Definity (n = 1/6), perfienapent emulsion (n = 1/6), and perfluorocarbon-exposed sonicated dextrose albumin (n = 1/6) was mixed. These studies detected an average accuracy of 91 ± 11% (n = 2/3% > 80%), sensitivity of 98% ± 4%, (n = 3/3% > 80%), and specificity of 86% ± 10% (n = 2/3% > 80%). Included studies had generally low risk of bias and applicability concerns except for unclear flow and timing (n = 7/11) and applicability of patient selection (n = 4/11).

CONCLUSION

Despite being limited by the heterogeneity of included studies, our review indicates a high overall diagnostic accuracy for CEUS to detect RAS compared to angiography, with the largest evidence-base for SonoVue contrast. Radiologists and hospital decision makers should consider CEUS as an acceptable alternative to angiography.

Cost-effectiveness modelling in diagnostic imaging: a stepwise approach

Abstract

Diagnostic imaging (DI) is the fastest growing sector in medical expenditures and takes a central role in medical decision-making. The increasing number of various and new imaging technologies induces a growing demand for cost-effectiveness analysis (CEA) in imaging technology assessment. In this article we provide a comprehensive framework of direct and indirect effects that should be considered for CEA in DI, suitable for all imaging modalities. We describe and explain the methodology of decision analytic modelling in six steps aiming to transfer theory of CEA to clinical research by demonstrating key principles of CEA in a practical approach. We thereby provide radiologists with an introduction to the tools necessary to perform and interpret CEA as part of their research and clinical practice.

Key Points

• DI influences medical decision making, affecting both costs and health outcome.

• This article provides a comprehensive framework for CEA in DI.

• A six-step methodology for conducting and interpreting cost-effectiveness modelling is proposed.

ACR Appropriateness Criteria(®) on renal failure

Imaging plays a role in the management of patients with acute kidney injury or chronic kidney disease. However, clinical circumstances strongly impact the appropriateness of imaging use. In patients with newly detected renal dysfunction, ultrasonography can assess for reversible causes, assess renal size and echogenicity, and thus, establish the chronicity of disease. Urinary obstruction can be detected, but imaging is most useful in high-risk groups or in patients in whom there is a strong clinical suspicion for obstruction. Computed tomography, computed tomography or magnetic resonance arteriography, and percutaneous ultrasound-guided renal biopsy are valuable in other clinical situations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

How to include informal care in economic evaluations

Economic evaluations of health interventions aim to support decision making in healthcare. To effectively do so, evaluations need to include all relevant costs and effects of an intervention. Informal care provided by family or friends is an important element of care for many patients, but can have a profound impact on the health and well-being of carers. Therefore, informal care should be considered in economic evaluations of health interventions. Different methods to do so exist. This paper provides an overview of state-of-the-art methods available for this purpose, illustrated with practical examples. Since the choice of measurement and valuation technique depends on the type and perspective of the economic evaluation, this paper supports researchers in choosing the appropriate techniques to include informal care in their economic evaluation of a health intervention. We discuss the different approaches to measuring and valuing informal care, covering both partial and full valuation methods, allowing inclusion as costs or effects.

Screening for significant atherosclerotic renal artery stenosis with a regression model in patients undergoing transradial coronary angiography/intervention

OBJECTIVE

Early detection of atherosclerotic renal artery stenosis (ARAS) is clinically important with respect to blood pressure control, prevention of renal insufficiency, and even improving survival. We investigated whether the presence of significant ARAS (luminal diameter narrowing ≥70%) could be predicted using a logistic regression model before coronary angiography/intervention.

METHODS

Initially, we developed a logistic regression model for detecting significant ARAS based upon clinical and angiographic features and biochemical measurements in a cohort of 1813 patients undergoing transfemoral coronary and renal angiography. This model was then prospectively applied to an additional 495 patients who received transradial renal angiography to ascertain its predictive accuracy for the presence of significant ARAS.

RESULTS

Multivariate regression analysis revealed that older age (≥65 years), resistant hypertension, type 2 diabetes, creatinine clearance (Ccr) ≤60 ml/min, and multivessel coronary disease were independent predictors for significant ARAS. A logistic regression model for detecting ARAS by incorporating conventional risk factors and multivessel coronary disease was generated as: P/(1-P)=exp(-2.618+1.112[age≥65 years]+1.891[resistant hypertension]+0.453[type 2 diabetes]+0.587[Ccr≤60 ml/min]+2.254[multivessel coronary disease]). When this regression model was prospectively applied to the additional 495 patients undergoing transradial coronary and renal angiography, significant ARAS could be detected with a sensitivity of 81.2%, specificity of 88.9%, and positive and negative predictive accuracies of 53.8% and 96.7%, respectively.

CONCLUSIONS

The logistic regression model generated in this study may be useful for screening for significant ARAS in patients undergoing transradial coronary angiography/intervention.

The inclusion of informal care in applied economic evaluation: a review

OBJECTIVE

Theory and guidelines advocating the inclusion of informal care in economic evaluation have, in recent years, been accompanied by developments in the methods for capturing the costs and outcomes related to informal care. The objective of this study was to review applied economic evaluations to identify the methods used for, and implications of, including informal care in practice.

METHODS

Searches of key databases were conducted to identify all full economic evaluations incorporating costs or outcomes relating to informal care. Information was extracted by using a standard template from all studies meeting the inclusion criteria.

RESULTS

Thirty economic evaluations were identified that included informal care. Twenty-five of these studies costed carers' time input and 17 measured outcomes for carers. The reported cost-effectiveness of interventions was altered by including informal care, in some cases changing the key conclusions for health care funding.

CONCLUSIONS

Theory and methods development around informal care are yet to significantly permeate the applied literature; however, the results suggest that some funding priorities may change if they were to do so. The development of 1) a reference case for including informal care; 2) sensitivity analysis for contentious issues; and 3) a statement for the reason for excluding informal care, if this is deemed appropriate, may help to improve the way that informal care is included in economic evaluations in the future.

Newer CT applications and their alternatives: what is appropriate in children?

Innovations in image acquisition and reconstruction technologies have greatly expanded the range of CT applications available in the routine clinical setting. CT images of sub-millimeter resolution can now be acquired of entire body regions in a few seconds or even sub-second time, allowing depiction of fine anatomical detail uncompromised by motion artifact. With sophisticated visualization software, image data can be processed into multiplanar, volume-rendered, cine and other formats to better display anatomical abnormalities and facilitate newer applications such as CT angiography, enterography, urography, tracheobronchography and cardiac CT. Newer applications including dual-energy material decomposition CT are furthering the transition of CT from a purely morphological to a combined anatomical, functional and metabolic imaging technique. These newer applications have largely been pioneered in adult populations, and heightened concern of the risk of carcinogenesis from ionizing radiation tempers dissemination of their use in children. Similar information can often be gleaned from alternative imaging modalities without ionizing radiation exposure, such as MRI and US, and what is most appropriate in children will depend on relative diagnostic efficacy, cost, availability and local expertise.

[Renal artery fibromuscular dysplasia]

Fibromuscular dysplasia (FMD) encompasses a heterogeneous group of idiopathic, segmental, nonatherosclerotic diseases of the musculature of arterial walls, leading to the narrowing of small and medium-sized arteries. The most common locations of FMD are renal arteries and carotid arteries. The diagnosis of FMD is made on the "string of beads" appearance of the arteries. The French Health Authority recommends performing a CT scan or an MRA to assess the diagnosis of FMD. A recent meta-analysis showed the cure rates using current definitions of hypertension cure are only 36% and 54% after angioplasty and surgery, respectively.

relationship between distribution of coronary artery lesions and renal artery stenosis in patients undergoing simultaneous coronary and renal angiography

Aims:

We evaluated the relationship between distribution of lesions in coronary tree and atherosclerotic renal artery stenosis (RAS).

Methods and results:

Data collected prospectively on 500 consecutive patients who underwent simultaneous renal angiography following coronary angiography. Overall prevalence of RAS was 26.2% (131 patients). Significant (≥50% luminal diameter stenosis) RAS was present in 70 patients (14%). In 346 individuals of the study population, significant CAD was present (69.2%). Significant RAS was more common (18.4%) in this group. Older age, higher intra-arterial systolic blood pressure (SBP) and pulse pressure (PP) at the time of catheterization, and 3-vessel coronary artery disease (CAD) were associated with significant RAS in univariate analysis. Relationship between involved locations of coronary arteries [Left anterior descending (LAD), left circumflex (LCX), Right Coronary Artery (RCA), and their ostio-proximal portions] and RAS were significant except for left main (LM) disease. In multivariate model, age more than 62 years, SBP greater than 150 mmHg, PP in excess of 60 mmHg and RCA involvement were independent predictors of significant RAS.

Conclusion:

Simultaneous renal angiography following coronary angiography might be justified in patients with significant RCA disease who are older with increased levels of intra-arterial SBP and PP.

Non-contrast-enhanced MR imaging of renal artery stenosis at 1.5 tesla

Balanced steady-state free precession (Bal-SSFP) techniques produce excellent anatomic images of renal arteries without the use of contrast agents and are relatively flow-insensitive. Electrocardiography (ECG)-triggered and non-ECG-triggered sequences have been shown to be quite sensitive for detection of regional arterial stenosis (RAS), and the already high specificity is likely to increase with further refinement of the techniques. Bal-SSFP sequences can be used as a screening tool or as an alternative to contrast-enhanced (CE) magnetic resonance angiography (MRA) when contrast agents are contraindicated. In addition to morphologic imaging of RAS, non-CE techniques can be used in functional assessment of hemodynamic significance. The complimentary tools can be used alone or in combination with CE-MRA for MR imaging of renal vascular hypertension.

Nuclear imaging in the genitourinary tract: recent advances and future directions

For almost three decades, noninvasive radionuclide procedures for the evaluation of renal disease have been important components of nuclear medicine practice. With the introduction of new imaging agents and procedures, these techniques can provide valuable data on perfusion and function of individual kidneys. In general, these procedures are easy to perform and carry a low radiation burden and sedation is not required. Moreover, radionuclide imaging of the genitourinary tract has become an invaluable asset to clinicians in the evaluation of renal parenchyma and urologic abnormalities.