Magnetic resonance angiography in progressive renal failure: a technology assessment

Cost-effectiveness of administering oral adsorbent AST-120 to patients with diabetes and advance-stage chronic kidney disease

AIMS

AST-120, an oral adsorbent currently on-label only in Asian countries with phase III trials ongoing in the US, slows renal disease progression in patients with diabetes and advanced-stage chronic kidney disease (CKD). The objective of this study is to evaluate the cost-effectiveness of using AST-120 to treat patients with type 2 diabetes and advanced-stage CKD.

METHODS

We used Markov model simulating the progression of diabetic nephropathy. Data were obtained from randomized trials estimating the progression of diabetic nephropathy with and without AST-120, and published literature. The base population was patients 60 years of age with type 2 diabetes and Stages 3 and 4 CKD.

RESULTS

Treating patients with diabetes and advanced-stage CKD was found to be a dominant strategy, and quality of life improved further and more money was saved (0.22 quality-adjusted life years [QALYs] and $15,019 per patient) using AST-120 than the control strategy. Sensitivity analysis results were robust with regard to cost, adherence, and quality of life associated with AST-120 therapy, as well as age at diagnosis. The model was relatively sensitive to the effectiveness of AST-120.

CONCLUSIONS

Treating patients with type 2 diabetes and advanced-stage CKD with AST-120 appears to extend life and reduce costs.

A review of methods used in long-term cost-effectiveness models of diabetes mellitus treatment

Diabetes mellitus is a major healthcare concern from both a treatment and a funding perspective. Although decision makers frequently rely on models to evaluate the long-term costs and consequences associated with diabetes interventions, no recent article has reviewed the methods used in long-term cost-effectiveness models of diabetes treatment. The following databases were searched up to April 2008 to identify published economic models evaluating treatments for diabetes mellitus: OVID MEDLINE, EMBASE and the Thomson's Biosis Previews, NHS EED via Wiley's Cochrane Library, and Wiley's HEED database. Identified articles were reviewed and grouped according to unique models. When a model was applied in different settings (e.g. country) or compared different treatment alternatives, only the original publication describing the model was included. In some cases, subsequent articles were included if they provided methodological advances from the original model. The following data were captured for each study: (i) study characteristics; (ii) model structure; (iii) long-term complications, data sources, methods reporting and model validity; (iv) utilities, data sources and methods reporting; (v) costs, data sources and methods reporting; (vi) model data requirements; and (vii) economic results including methods to deal with uncertainty. A total of 17 studies were identified, 12 of which allowed for the conduct of a cost-effectiveness analysis and a cost-utility analysis. Although most models were Markov-based microsimulations, models differed with respect to the number of diabetes-related complications included. The majority of the studies used a lifetime time horizon and a payer perspective. The DCCT for type 1 diabetes and the UKPDS for type 2 diabetes were the trial data sources most commonly cited for the efficacy data, although several non-randomized data sources were used. While the methods used to derive the efficacy data were commonly reported, less information was given regarding the derivation of the utilities or the costs. New interventions were generally deemed cost effective based on ten studies presenting results. Authors relied mostly on univariate sensitivity analyses to test the robustness of their models. Although diabetes is a complex disease, several models have been developed to predict the long-term costs and consequences associated with diabetes treatment. Combined with previous findings, this review supports the development of a reference case that could be used for any new diabetes models. Models could be enhanced if they had the capacity to deal with both first- and second-order uncertainty. Future research should continue to compare economic models for diabetes treatment in terms of clinical outcomes, costs and QALYs when applicable.

Renal Artery Stenosis: Cost-effectiveness of Diagnosis and Treatment

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 (euro54 415) and most effective (12.265 QALYs) strategy. For the other strategies, costs and QALYs, respectively, were euro55 570 and 12.195 for DSA, euro55 191 and 12.163 for CT angiography, and euro56 890 and 12.088 for MR angiography. For a 50-year-old female patient, costs and QALYs, respectively, were euro66 731 and 13.731 for MR angiography, euro63 970 and 13.749 for CT angiography, and euro63 079 and 13.902 for DSA. Immediate tentative revascularization yielded more QALYs (13.937) and was more costly (euro63 329) than DSA. The incremental cost-effectiveness ratio was euro7143 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.

Predicted quality-adjusted life years as a composite measure of the clinical value of diabetes risk factor control

BACKGROUND

Control of blood pressure, low-density lipoprotein cholesterol (LDL-c), and A1c can lower the risk for diabetes complications. These quality indicators often are examined separately and weighted equally in performance measurement, potentially discarding important information.

OBJECTIVES

We sought to create a composite indicator of the clinical benefit, or value, of diabetes risk factor control that appropriately weights the clinical importance of A1c, LDL-c, and blood pressure, and to test its usability for quality measurement.

METHODS

The combined value of control for 3 diabetes risk factors, measured by predicted quality-adjusted life years (QALYs), was compared in diabetes patients (n = 129,236 in 2001; n = 185,006 in 2003) in Kaiser Permanente Northern California across 16 medical center populations in 2001 and 2003 using hierarchical linear regression to adjust for case-mix differences. Patient-level QALYs, simulated from risk factor and case-mix variables in a Markov model, was the main outcome variable.

RESULTS

There was significant cross-sectional variability in average case-mix adjusted QALYs for diabetes patients across centers in 2003. QALYs increased from 2001 to 2003 as the result of improved risk factor control; longitudinal improvements in QALYs also showed variation across centers. Regression analyses demonstrated the greater impact of blood pressure versus LDL-c or A1c control on QALYs, and the greater value of risk factor control in those with poor versus near or in-control blood pressure.

CONCLUSION

Using predicted QALYs to measure value holds promise as a sensitive composite indicator for quality measurement. Complex, evidence-based quality indicators such as these can potentially provide accurate and useful information to health plans, providers, and consumers.

Health-economic comparison of paricalcitol, calcitriol and alfacalcidol for the treatment of secondary hyperparathyroidism during haemodialysis

This study evaluated the health-economic consequences of use of intravenous paricalcitol (Zemplar), oral calcitriol or oral and intravenous alfacalcidol for the treatment of patients with secondary hyperparathyroidism, focusing on a third-party payer perspective through inclusion of medication and hospital costs, survival rates and utilities. Cost values were based on German treatment recommendations and prices. Reference values for survival rates and utilities were based on the results of a MEDLINE search. The analysis showed a clear advantage for intravenous paricalcitol with respect to costs, effectiveness and utilities compared with treatment with oral calcitriol or intravenous alfacalcidol. Since the results were very cost sensitive with respect to selected diagnosis-related groups (DRGs) for kidney disease with dialysis, a sensitivity analysis was performed. This demonstrated first-order dominance of intravenous paricalcitol for a wide range of hospitalisation costs. In conclusion, this analysis suggested a clear benefit from the perspective of a third-party payer for intravenous paricalcitol compared with oral calcitriol and intravenous alfacalcidol in the treatment of patients with secondary hyperparathyroidism.

The cost-effectiveness of lanthanum carbonate in the treatment of hyperphosphatemia in patients with end-stage renal disease

OBJECTIVE

To assess the cost-effectiveness of lanthanum carbonate (LC) as a second-line therapy for hyperphosphatemia in end-stage renal disease (ESRD) patients not achieving target phosphorus levels.

METHODS

A cohort of ESRD patients not adequately maintained on calcium carbonate (CC) and three subgroups of patients with baseline phosphorus levels of 5.6 to 6.5 mg/dl, 6.6 to 7.8 mg/dl, and more than 7.9 mg/dl were modeled. The following policy options were considered: continued CC (Policy 1); LC trial-if successful continue LC, if unsuccessful switch to CC (Policy 2). The survival benefit of using second-line LC to improve phosphorus control has been extrapolated from the relationship between hyperphosphatemia and mortality. Lifetime UK National Health Service drug and monitoring costs, expected survival, and quality-adjusted life-years (QALYs) were examined (discounting at 3.5% per annum).

RESULTS

Policy 2 had a cost-effectiveness ratio (cost/QALY) of pound25,033 relative to Policy 1. The results show it is particularly cost-effective to treat patients with phosphorus levels above 6.6 mg/dl. The outcomes did not vary significantly during the one-way sensitivity analysis carried out on important model parameters and assumptions except when the utility value for ESRD was decreased by more than 30%.

CONCLUSIONS

Applying a cost-effectiveness threshold of pound30,000 per QALY, the model shows it is cost-effective to follow current treatment guidelines and treat all patients who are not adequately maintained on CC (serum phosphorus above 5.6 mg/dl) with second-line LC. This is particularly the case for patients with serum phosphorus above 6.6 mg/dl. Our estimates are probably conservative as the possible compliance difference in favor of LC and the reduced number of hypercalcemic events with LC relative to CC was not considered.

The impact of patient preferences on the cost-effectiveness of intensive glucose control in older patients with new-onset diabetes

OBJECTIVE

Cost-effectiveness analyses have reported that intensive glucose control is not cost-effective in older patients with new-onset diabetes. However, these analyses have had limited data on patient preferences concerning diabetic health states. We examined how the cost- effectiveness of intensive glucose control changes with the incorporation of patient preferences.

RESEARCH DESIGN AND METHODS

We collected health state preferences/utilities from 519 older diabetic patients. We incorporated these utilities into an established cost-effectiveness model of intensive glucose control and compared incremental cost-effectiveness analyses ratios (ICERs) (cost divided by quality-adjusted life-year [QALY]) when using the original and patient-derived utilities for complications and treatments.

RESULTS

The mean utilities were approximately 0.40 for major complications, 0.76 (95% CI 0.74-0.78) for conventional glucose control, 0.77 (0.75-0.80) for intensive therapy with oral medications, and 0.64 (0.61-0.67) for intensive therapy with insulin. Incorporating our patient-derived complication utilities alone improved ICERs for intensive glucose control (e.g., patients aged 60-65 years at diagnosis, 136,000 dollars/QALY-->78,000 dollars/QALY), but intensive therapy was still not cost-effective at older ages. When patient-derived treatment utilities were also incorporated, the cost-effectiveness of intensive treatment depended on the method of glucose control. Intensive control with insulin generated fewer QALYs than conventional control. However, intensive control with oral medications was beneficial on average at all ages and had an ICER < or =100,000 dollars to age 70.

CONCLUSIONS

The cost-effectiveness of intensive glucose control in older patients with new-onset diabetes is highly sensitive to assumptions regarding quality of life with treatments. Cost-effectiveness analyses of diabetes care should consider the sensitivity of results to alternative utility assumptions.

Cost analysis of procedures related to the management of renal artery stenosis from various perspectives

To determine the costs associated with the diagnostic work-up and percutaneous revascularization of renal artery stenosis from various perspectives. A prospective multicenter comparative study was conducted between 1998 and 2001. A total of 402 hypertensive patients with suspected renal artery stenosis were included. Costs were assessed of computed tomography angiography (CTA), magnetic resonance angiography (MRA), digital subtraction angiography (DSA), and percutaneous revascularization. From the societal perspective, DSA was the most costly (euro 1,721) and CTA the least costly diagnostic technique (euro 424). CTA was the least costly imaging procedure irrespective of the perspective used. The societal costs associated with percutaneous renal artery revascularization ranged from euro 2,680 to euro 6,172. Overall the radiology department incurred the largest proportion of the total societal costs. For the management of renal artery stenosis, performing the analysis from different perspectives leads to the same conclusion concerning the least costly diagnostic imaging and revascularization procedure.

Health and economic impact of combining metformin with nateglinide to achieve glycemic control: Comparison of the lifetime costs of complications in the U.K

BACKGROUND: To reduce the likelihood of complications in persons with type 2 diabetes, it is critical to control hyperglycaemia. Monotherapy with metformin or insulin secretagogues may fail to sustain control after an initial reduction in glycemic levels. Thus, combining metformin with other agents is frequently necessary. These analyses model the potential long-term economic and health impact of using combination therapy to improve glycemic control. METHODS: An existing model that simulates the long-term course of type 2 diabetes in relation to glycosylated haemoglobin (HbA1c) and post-prandial glucose (PPG) was used to compare the combination of nateglinide with metformin to monotherapy with metformin. Complication rates were estimated for major diabetes-related complications (macrovascular and microvascular) based on existing epidemiologic studies and clinical trial data. Utilities and costs were estimated using data collected in the United Kingdom Prospective Diabetes Study (UKPDS). Survival, life years gained (LYG), quality-adjusted life years (QALY), complication rates and associated costs were estimated. Costs were discounted at 6% and benefits at 1.5% per year. RESULTS: Combination therapy was predicted to reduce complication rates and associated costs compared with metformin. Survival increased by 0.39 (0.32 discounted) and QALY by 0.46 years (0.37 discounted) implying costs of pound 6,772 per discounted LYG and pound 5,609 per discounted QALY. Sensitivity analyses showed the results to be consistent over broad ranges. CONCLUSION: Although drug treatment costs are increased by combination therapy, this cost is expected to be partially offset by a reduction in the costs of treating long-term diabetes complications.

Cost effectiveness of ACE inhibitor treatment for patients with type 1 diabetes mellitus

OBJECTIVE

Current guidelines recommend treating patients with type 1 diabetes mellitus with ACE inhibitors after the onset of microalbuminuria. Recent clinical trials have shown ACE inhibitors can affect the development of nephropathy when initiated prior to the onset of microalbuminuria. Our objective is to examine the cost effectiveness of treating adults aged over 20 years with an ACE inhibitor (captopril) immediately following diagnosis of type 1 diabetes versus treating them after the onset of microalbuminuria.

DESIGN

Using a semi-Markov model, we calculated four main outcome measures: lifetime direct medical costs (discounted), QALYs, cumulative incidence of end-stage renal disease (ESRD), and number of days of ESRD over a lifetime. Medical costs are in 1999 US dollars.

SETTING

All analyses were from the viewpoint of a single US payer responsible for all direct medical costs, including screening for microalbuminuria, ACE inhibitor treatment (captopril), management of major diabetic complications, and routine annual medical costs not specific to diabetes.

METHODS

We applied the model to a hypothetical cohort of 10,000 persons newly diagnosed with type 1 diabetes. Distribution of sex and race/ethnicity within the cohort is representative of the general US population.

RESULTS

We estimated that the incremental cost of early use of captopril for the average adult with type 1 diabetes is USD 27,143 per QALY. This level varies considerably with age and glycaemic level. When the age at onset of diabetes is 20 years and glycosylated haemoglobin (HbA(1c)) level is 9%, the cost-effectiveness ratio is USD 13,814 per QALY. When the age at onset is 25 years and HbA(1c) level is 7%, the cost-effectiveness ratio is USD 39,530 per QALY.

CONCLUSION

This model, with its underlying assumptions and data, suggests that early treatment with captopril provides modest benefit at reasonable cost effectiveness, from the US single-payer perspective, in the prevention of ESRD compared with delaying treatment until diagnosis of microalbuminuria. Early treatment with other ACE inhibitors will provide similar cost effectiveness if they have equivalent efficacy, compliance and price per dose. Treatment may be considered among patients at age 20 years with new onset of type 1 diabetes. This conclusion is sensitive to the extent that ACE inhibitors delay onset of microalbuminuria. Other factors such as the patient's age and glycaemic level must be considered when deciding to initiate early treatment.

The impact of atherosclerotic renovascular disease on diabetic renal failure

Atherosclerotic renovascular disease (ARVD) is common in the general population, and its prevalence increases with age. Parallel studies show it is also common in patients with diabetes. The widespread use of angiotensin converting enzyme inhibitors and angiotensin receptor antagonists for heart and kidney disease might therefore expose arteriopathic diabetic patients to potential harm if they had critical renal artery stenosis. This review looks at the natural history of ARVD in the diabetic and non-diabetic populations: while it is common, it only rarely leads to renal failure. Hence intervention to revascularize ischaemic kidney son the basis of radiological appearances alone may subject some patients to unnecessary therapy. Although untested by randomized trial, a policy of watchful waiting may be the simplest strategy for most diabetic patients with suspected ARVD, reserving angiography and angioplasty (usually backed up by a stent) for those with an abrupt decline in renal function and no other cause for renal deterioration. Future clinical trials may better define subgroups of patients who will truly benefit from renal revascularization.

Effect of future costs on cost-effectiveness of medical interventions among young adults: the example of intensive therapy for type 1 diabetes mellitus

OBJECTIVES

Recent research based on a lifetime utility maximization model has suggested that cost-effectiveness analyses should account for all future costs, including medical costs for related and unrelated illnesses and nonmedical costs. This work has also shown that analyses that omit future costs are biased to favor interventions among the elderly that extend life over interventions that improve quality of life. However, the effect of including future costs on the cost-effectiveness of interventions among the young has not been studied. This article examines the effect of including future costs on the cost-effectiveness of intensive therapy for type 1 diabetes mellitus among young adults.

METHODS

By modifying a cost-effectiveness model based on the Diabetes Control and Complications Trial to include future costs, the effect of including future costs on the cost-effectiveness of intensive therapy for type 1 diabetes mellitus among young adults was examined. Future costs added to the model included future costs for medical expenditures for illnesses unrelated to diabetes and future nonmedical expenditures net of earnings.

RESULTS

Intensive therapy among young adults led to approximately equal increases in the expected number of years lived before age 65, when people generally produce more than they consume, and after age 65, when the opposite tends to hold. Because the discounted value of savings due to lower mortality before age 65 exceeded the discounted value of later increases in costs due to lower mortality after age 65, accounting for future costs decreased the cost-effectiveness ratio from $22,576 to $9,626 per quality-adjusted life-year.

CONCLUSIONS

The inclusion of future costs can significantly improve the cost-effectiveness of interventions that decrease mortality among young adults. The common practice of excluding future costs may bias cost-effectiveness analyses against such interventions.

Surgical renal artery reconstruction without contrast arteriography: the role of clinical profiling and magnetic resonance angiography

PURPOSE

Contrast arteriography is the accepted gold standard for diagnosis and treatment planning in patients with atherosclerotic renovascular disease (RVD). In this study, the results of a selective policy of surgical renal artery reconstruction (RAR) with magnetic resonance angiography (MRA) as the sole preoperative imaging modality are reviewed.

METHODS

From May 1993 to May 1998, 25 patients underwent RAR after clinical evaluation, and aortic/renal MRA performed with a gadolinium-enhanced and 3-dimensional phase contrast technique. Clinical presentations suggested severe RVD in all patients and included poorly controlled hypertension (16 patients), hospitalization for hypertensive crises and/or acute pulmonary edema (13), and deterioration of renal function within one year of operation (15). Thirteen patients had associated aortic pathologic conditions (12 aneurysms, 1 aortoiliac occlusive disease), and eight of these patients also underwent noncontrast computed tomography scans. Significant renal dysfunction (serum creatinine level, >/=2.0 mg/dL) was present in all but 4 patients with 14 of 25 patients having extreme (creatinine level, >/=3.0 mg/dL) dysfunction.

RESULTS

Hemodynamically significant RVD in the main renal artery was verified at operation in 37 of 38 reconstructed main renal arteries (24/25 patients). A single accessory renal artery was missed by MRA. RAR was comprehensive (bilateral or unilateral to a single-functioning kidney) in 21 of 25 patients and consisted of hepatorenal bypass graft (3 patients), combined aortic and RAR (13 patients), isolated transaortic endarterectomy (8 patients), and aortorenal bypass graft (1 patient). Early improvement in both hypertension control and/or renal function was noted in 21 of 25 patients without operative deaths or postoperative renal failure. Sustained favorable functional results at follow-up, ranging from 5 months to 4 years, were noted in 19 of 25 patients.

CONCLUSION

MRA is an adequate preoperative imaging modality in selected patients before RAR. This strategy is best applied in circumstances where the clinical presentation suggests hemodynamically significant bilateral RVD and/or in patients at substantial risk of complications from contrast angiography.

Economic analyses of radiological procedures: a methodological evaluation of the medical literature

OBJECTIVE

Increasing pressure to curb health care costs has led to considerable interest in economic analyses, including both cost-effectiveness and cost-benefit analyses. Numerous economic analyses of radiological procedures have appeared in both the radiology and non-radiology literature. The objective of this study was to evaluate the methodological quality of economic analyses of radiological procedures published in the non-radiology medical literature during the years 1990 1995.

METHODS

Original investigations from the medical (non-radiological) literature that include economic analyses of radiological interventions were identified from a computerized literature search. Each economic analysis article was evaluated by two independent reviewers for adherence to ten methodological criteria. The criteria were derived from review of the medical and radiological economic analysis methodology literature and consisted of the following: (1) Comparative options stated; (2) perspective of analysis defined; (3) outcome measure identified; (4) cost data included; (5) source of cost data stated; (6) long term costs included; (7) discounting employed; (8) summary measure provided; (9) incremental computation method used; and (10) sensitivity analysis performed. The results were compared to a previous study that evaluated the radiological literature.

RESULTS

Of the 56 articles in the medical literature that included economic analyses of radiological procedures, only eight (14%) conformed to all ten methodological criteria. The cost data (98%) and comparative options (89%) criteria exhibited high compliance, while the perspective of analysis (25%) and discounting (32%) criteria had relatively low compliance. Agreement between the reviewers was excellent (kappa = 0.88).

CONCLUSIONS

Published economic analyses of radiology procedures usually do not meet accepted methodological standards.