Cost-effectiveness of irbesartan in diabetic nephropathy: a systematic review of published studies

Cost of diabetic eye, renal and foot complications: a methodological review

INTRODUCTION

Diabetic retinopathy (DR), diabetic kidney disease (DKD) and diabetic foot ulcer (DFU) represent a public health and economic concern that may be assessed with cost-of-illness (COI) studies.

OBJECTIVES

(1) To review COI studies published between 2000 and 2015, about DR, DKD and DFU; (2) to analyse methods used.

METHODS

Disease definition, epidemiological approach, perspective, type of costs, activity data sources, cost valuation, sensitivity analysis, cost discounting and presentation of costs may be described in COI studies. Each reviewed study was assessed with a methodological grid including these nine items.

RESULTS

The five following items have been detailed in the reviewed studies: epidemiological approach (59 % of studies described it), perspective (75 %), type of costs (98 %), activity data sources (91 %) and cost valuation (59 %). The disease definition and the presentation of results were detailed in fewer studies (respectively 50 and 46 %). In contrast, sensitivity analysis was only performed in 14 % of studies and cost discounting in 7 %. Considering the studies showing an average cost per patient and per year with a societal perspective, DR cost estimates were US $2297 (range 5-67,486), DKD cost ranged from US $1095 to US $16,384, and DFU cost was US $10,604 (range 1444-85,718).

DISCUSSION

This review reinforces the need to adequately describe the method to facilitate literature comparisons and projections. It also recalls that COI studies represent complementary tools to cost-effectiveness studies to help decision makers in the allocation of economic resources for the management of DR, DKD and DFU.

Review: PROactive 03: Pioglitazone, type 2 diabetes and reducing macrovascular events — economic implications?

conomic value of medicines, medical devices and other technologies is an increasingly important consideration in healthcare management. Conducting high quality economic analyses alongside randomised controlled clinical trials (RCTs) is desirable since these offer timely information with high internal validity. The recent publication of the landmark PROactive study provides a relevant platform upon which to base a detailed economic evaluation of the possible additional benefit of pioglitazone over and above current best treatment in patients with type 2 diabetes with severe cardiovascular (CV) disease. Pioglitazone improved CV outcome and reduced the need to add insulin to existing therapy in individuals at high risk of further macrovascular events. The predefined economic analysis of this study using well-accepted methods will inform the cost effectiveness (CE) of pioglitazone confirming (or not) its value in the management of patients with type 2 diabetes with severe CV disease.

Economic evaluations of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers in type 2 diabetic nephropathy: a systematic review

Background

Structured comparison of pharmacoeconomic analyses for ACEIs and ARBs in patients with type 2 diabetic nephropathy is still lacking. This review aims to systematically review the cost-effectiveness of both ACEIs and ARBs in type 2 diabetic patients with nephropathy.

Methods

A systematic literature search was performed in MEDLINE and EMBASE for the period from November 1, 1999 to Oct 31, 2011. Two reviewers independently assessed the quality of the articles included and extracted data. All cost-effectiveness results were converted to 2011 Euros.

Results

Up to October 2011, 434 articles were identified. After full-text checking and quality assessment, 30 articles were finally included in this review involving 39 study settings. All 6 ACEIs studies were literature-based evaluations which synthesized data from different sources. Other 33 studies were directed at ARBs and were designed based on specific trials. The Markov model was the most common decision analytic method used in the evaluations. From the cost-effectiveness results, 37 out of 39 studies indicated either ACEIs or ARBs were cost-saving comparing with placebo/conventional treatment, such as amlodipine. A lack of evidence was assessed for valid direct comparison of cost-effectiveness between ACEIs and ARBs.

Conclusion

There is a lack of direct comparisons of ACEIs and ARBs in existing economic evaluations. Considering the current evidence, both ACEIs and ARBs are likely cost-saving comparing with conventional therapy, excluding such RAAS inhibitors.

Economic evaluation of irbesartan in combination with hydrochlorothiazide in the treatment of hypertension in Greece

OBJECTIVES

Hypertension is a major risk factor for cardiovascular disease and a leading cause of morbidity and mortality. This study evaluates irbesartan in relation to commonly used alternative hypertension therapies losartan and valsartan given in combination with hydrochlorothiazide (HCTZ) in the general hypertensive population in Greece.

METHODS

A Markov model with eight states of health was constructed: hypertension, myocardial infarction (MI), post-MI, angina, stroke, poststroke, heart failure, and death. The model has an annual cycle and estimates mean quality-adjusted survival and treatment cost, which reflect the hypertension treatment and managing cardiovascular events. Risk functions were used to conduct extrapolations. Data on treatment effectiveness, quality of life (QOL) and epidemiology were obtained from published clinical trials and studies. The database of the main Greek National Social Insurance Institute (IKA) was analyzed to estimate the cost of events. The analysis was done from a payer perspective. All outcomes were discounted, and prices correspond to 2008.

RESULTS

The estimated patient cost per annum was stable angina euro 2,252, unstable angina euro 2,572, myocardial infarction euro 2,473, post-MI euro 1,677, stroke euro 12,233, poststroke euro 1,240, heart failure euro 2,655, coronary angiography euro 1,544, percutaneous transluminal coronary angioplasty euro 6,511, and coronary artery bypass graft surgery euro 11,514. For the baseline group (age 57 years, systolic blood pressure 147 mmHg, cholesterol 6.00 mmol/L, body mass index 29) of men with mild to moderate hypertension, for irbesartan, the total treatment cost was euro 15,146, for losartan euro 15,696 and for valsartan euro 15,613; the quality-adjusted life years (QALYs) were irbesartan 12.67, losartan 12.63 and valsartan 12.64. For the baseline group of women with mild to moderate hypertension, the total treatment cost was euro 12,945 for irbesartan, euro 13,424 for losartan and euro 13,379 for valsartan; QALYs were 14.29 for irbesartan, 14.27 for losartan and 14.27 for valsartan. For men with severe hypertension, for irbesartan and losartan, the total treatment cost was euro 18,679 and euro 21,488 and QALYs 12.47 and 12.37, respectively. For women, the total treatment cost was euro 16,202 and euro 19,099 and QALYs 14.16 and 14.09, respectively. Similar results were obtained in relation to other treatment groups in various sensitivity analysis scenarios.

CONCLUSIONS

Based on efficacy data from clinical trials and lower attainment costs in various hypertensive patient populations, irbesartan in combination with HCTZ compares favorably with losartan and valsartan in combination with HCTZ in the Greek setting.

Cost-effectiveness of irbesartan/hydrochlorothiazide in patients with hypertension: an economic evaluation for Sweden

Irbesartan, an angiotensin-II inhibitor, has been shown to be an effective antihypertensive agent in clinical trials. The purpose of this study was to assess the cost-effectiveness of irbesartan in combination with hydrochlorothiazide (HCTZ) in Swedish health-care setting by predicting clinical events and life years based upon observed reductions in blood pressure in clinical trials. The cost-effectiveness of antihypertensive treatment with irbesartan compared with placebo and to other selected angiotensin-II inhibitors (losartan, valsartan, candesartan) in combination with HCTZ was estimated using a Markov model. The incidence of cardiovascular disease was obtained from the Swedish inpatient registry, whereas the risk reductions associated with antihypertensive therapy were taken from the medical literature. Costs for antihypertensive therapy and for treatment of cardiovascular events were included, and the health effects were measured in terms of quality-adjusted life years (QALYs). The study was conducted from a health-care payer perspective. For a 55-year-old male, irbesartan 150 mg/HCTZ 12.5 mg was a dominant strategy (better health effects at lower costs) when compared with losartan 50 mg/HCTZ 12.5 mg and valsartan 80 mg/HCTZ 12.5 mg, and the cost-effectiveness ratio compared with placebo was 3500 euros per QALY gained. In moderate-to-severe hypertension, irbesartan was cost-effective compared with losartan, whereas the results compared with candesartan were mixed. High-dose combination therapy of irbesartan was also found to be cost-effective compared with low-dose combination therapy. The results from the model indicate that irbesartan provides a cost-effective antihypertensive treatment strategy compared with both placebo, and to valsartan and losartan.

Economic benefits of treating high-risk hypertension with angiotensin II receptor antagonists (blockers)

Hypertension is one of the leading risk factors for cardiovascular disease and represents a major health and economic burden. Most patients with high- or very high-risk hypertension have multiple cardiovascular risk factors with or without accompanying subclinical organ damage or established cardiovascular or renal disease. Patients with severe hypertension or with moderate hypertension and one to two additional risk factors have absolute 10-year risks of cardiovascular disease of 21-30% and 15-20%, respectively. Current European treatment guidelines recommend that antihypertensive therapy be initiated rapidly and aggressively in patients with high-risk hypertension. Most patients require two or more antihypertensive agents to achieve the strict blood pressure target of <130/80 mmHg. This article reviews the existing cost-effectiveness data on the use of angiotensin II receptor antagonists (blockers) [ARBs] in patients with high-risk hypertension. Aggressive ARB treatment of patients in the early (microalbuminuric) stages of diabetic nephropathy has a significant renoprotective effect, delaying the onset of overt (proteinuric) nephropathy. By slowing the progression of these patients to end-stage renal disease, substantial cost savings can be made. There is a paucity of cost-effectiveness data regarding the use of fixed-dose ARB plus thiazide diuretic combination therapies. Longitudinal cost-benefit studies of this attractive and efficacious first-line treatment option are needed.

Need for quality improvement in renal systematic reviews

BACKGROUND AND OBJECTIVES

Systematic reviews of clinical studies aim to compile best available evidence for various diagnosis and treatment options. This study assessed the methodologic quality of all systematic reviews relevant to the practice of nephrology published in 2005.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched electronic databases (Medline, Embase, American College of Physicians Journal Club, Cochrane) and hand searched Cochrane renal group records. Clinical practice guidelines, case reports, narrative reviews, and pooled individual patient data meta-analyses were excluded. Methodologic quality was measured using a validated questionnaire (Overview Quality Assessment Questionnaire). For reviews of randomized trials, we also evaluated adherence to recommended reporting guidelines (Quality of Reporting of Meta-Analyses).

RESULTS

Ninety renal systematic reviews were published in year 2005, 60 of which focused on therapy. Many systematic reviews (54%) had major methodologic flaws. The most common review flaws were failure to assess the methodologic quality of included primary studies and failure to minimize bias in study inclusion. Only 2% of reviews of randomized trials fully adhered to reporting guidelines. A minority of journals (four of 48) endorsed adherence to consensus guidelines for review reporting, and these journals published systematic reviews of higher methodologic quality (P < 0.001).

CONCLUSIONS

The majority of systematic reviews had major methodologic flaws. The majority of journals do not endorse consensus guidelines for review reporting in their instructions to authors; however, journals that recommended such adherence published systemic reviews of higher methodologic quality.

A cost-effectiveness analysis of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in diabetic nephropathy

The aim of this study was to estimate the cost-effectiveness of renin-angiotensin-aldosterone system blockers in patients with diabetic nephropathy. A cost-effectiveness analysis was performed based on a meta-analysis of studies investigating the effect of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) as part of a treatment regimen on the incidence of end-stage renal disease (ESRD) in patients with diabetic nephropathy. The primary outcome was the cost to prevent 1 patient from developing ESRD. Cost analysis was performed from a third-party payer perspective in 2006 US dollars. As part of a treatment regimen, ARBs significantly reduced the incidence of ESRD and doubling of serum creatinine concentration (P<.05) but not total mortality. The cost to prevent 1 patient from developing ESRD was $31,729 (95% confidence interval, $19,443-$85,442; P<.01), $189,190 (P=.13) and $51,585 (P=.068) for patients receiving ARBs, ACE inhibitors, or either of them, respectively. This study demonstrates that blocking the RAAS, which delays the progression to ESRD, appears to be cost-effective. The current analysis favors ARBs in terms of cost-effectiveness.

An Asian regional analysis of cost-effectiveness of early irbesartan treatment versus conventional antihypertensive, late amlodipine, and late irbesartan treatments in patients with type 2 diabetes, hypertension, and nephropathy

OBJECTIVE

The prevalence of type 2 diabetes, often leading to diabetic nephropathy, has increased globally, especially in Asia. Irbesartan treatment delays the progression of kidney disease at the early (microalbuminuria) and late (proteinuria) stages of nephropathy in hypertensive type 2 diabetics. This treatment has proven to be cost-effective in Western countries. This study assessed the cost-effectiveness of early irbesartan treatment in Asian settings.

METHODS

An existing lifetime model was reprogrammed in Microsoft Excel to compare irbesartan started at an early stage to irbesartan or amlodipine started at a late stage, and standard treatments from a health-care perspective in China, Malaysia, Thailand, South Korea, and Taiwan. The main effectiveness parameters were incidences of end-stage renal disease, time in dialysis, and life expectancy. All costs were converted to 2004 US$ using official purchasing power parity. Local data were obtained for costs, transplantation,dialysis, and mortality rates. Probabilities regarding disease progression after treatment with the investigated drugs were extracted from two published clinical trials. A probabilistic sensitivity analysis was performed.

RESULTS

Early use of irbesartan yielded the largest clinical and economic benefits reducing need for dialysis by 61% to 63% versus the standard treatment, total costs by 9% (Thailand) to 42% (Taiwan), and increasing life expectancy by 0.31 to 0.48 years. Early irbesartan had a 66% (Thailand) to 95% (Taiwan) probability of being dominant over late irbesartan.

CONCLUSION

Although the absolute results varied in different settings, reflecting differences in epidemiology, management, and costs, early irbesartan treatment was a cost-effective alternative in the Asian settings.

Taking the pressure off type 2 diabetes mellitus: implementing hypertension guidelines

Successful treatment of hypertension in patients with type 2 diabetes mellitus increases life expectancy and reduces the risk of many of the complications associated with diabetes, such as heart disease, stroke, and retinopathy. Controlling blood pressure also protects against advancing renal disease, with several recent studies having clearly shown the advantage of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in slowing the progression of renal disease. Here, the authors review current guidelines for the management of hypertension in patients with type 2 diabetes mellitus and explore ways in which nurse practitioners can improve care for these patients.

Lost in publication: Half of all renal practice evidence is published in non-renal journals

Physicians often scan a select number of journals to keep up to date with practice evidence for patients with kidney conditions. This raises the question of where relevant studies are published. We performed a bibliometric analysis using 195 renal systematic reviews. Each review used a comprehensive method to identify all primary studies for a focused clinical question relevant to patient care. We compiled all the primary studies included in these reviews, and considered where each study was published. Of the 2779 studies, 1351 (49%) were published in the top 20 journals. Predictably, this list included Transplantation Proceedings (5.9% of studies), Kidney International (5.3%), American Journal of Kidney Diseases (4.7%), Nephrology Dialysis Transplantation (4.3%), Transplantation (4.2%), and Journal of the American Society of Nephrology (2.4%). Ten non-renal journals were also on this list, including New England Journal of Medicine (2.4%), Lancet (2.3%), and Diabetes Care (2.2%). The remaining 1428 (51%) studies were published across other 446 journals. When the disciplines of all journals were considered, 59 were classified as renal or transplant journals (42% of articles). Other specialties included general and internal medicine (16%), endocrinology (diabetes) and metabolism (6.5%), surgery (6.2%), cardiovascular diseases (6.1%), pediatrics (4.3%), and radiology (3.3%). About half of all renal practice evidence is published in non-renal journals. Browsing the top journals is important. However, relevant studies are also scattered across a large range of journals that may not be routinely scanned by busy physicians, and keeping up with this literature requires other continuing education strategies.