Cost Comparison of Urate-Lowering Therapies in Patients with Gout and Moderate-to-Severe Chronic Kidney Disease

Projected Health and Economic Burden of Comorbid Gout and Chronic Kidney Disease in a Virtual US Population: A Microsimulation Study

INTRODUCTION

Gout, a common comorbidity of chronic kidney disease (CKD), is associated with high morbidity and healthcare utilization. However, a large proportion of gout remains undermanaged or untreated which may lead to worse patient outcomes and greater healthcare costs. This study estimates the present and future health and economic burden of controlled and uncontrolled gout in a virtual United States (US) CKD population.

METHODS

A validated microsimulation model was used to project the burden of gout in patients with CKD in the USA through 2035. Databases were utilized to build a virtual CKD population of "individuals" with controlled or uncontrolled gout. Modelling assumptions were made on the basis of the literature, which was sparse in some cases. Health and economic outcomes with the current care (baseline) scenario were evaluated, along with potential benefits of urate-lowering intervention scenarios.

RESULTS

The prevalence of comorbid gout and CKD in the USA was projected to increase by 29%, from 7.9 million in 2023 to 9.6 million in 2035 in the baseline scenario. Gout flares, tophi, and comorbidity development were also projected to increase markedly through 2035, with the economic burden of gout in the CKD population subsequently increasing from $38.9 billion in 2023 to $47.3 billion in 2035. An increased use of oral urate-lowering therapies in undermanaged patients, and pegloticase use in patients refractory to oral urate-lowering therapies were also project to result in 744,000 and 353,000 fewer uncontrolled gout cases, respectively, by 2035. Marked reductions in complications and costs ensued.

CONCLUSIONS

This study projected a substantial increase in comorbid gout and CKD. However, improved use of urate-lowering interventions could mitigate this growth and reduce the health and economic burdens of gout.

Cost-effectiveness of allopurinol versus febuxostat in the treatment of gout patients: A systematic review

Background: In recent years, increased longevity, poor dietary habits, and the rising prevalence of metabolic syndrome and hypertension have increased the prevalence of gout. Gout significantly increases direct and indirect costs and reduces the quality of life. Allopurinol and febuxostat are the most commonly used drugs for reducing uric acid levels and controlling this disease with different cost-effectiveness. The present systematic review compares the cost-effectiveness of these drugs. Methods: This was a systematic review of economic evaluations. Cochrane CENTRAL, Web of Science, PubMed, Embase, and the Cost-Effectiveness Analysis (CEA) Registry were searched up to April 30, 2018, based on the specific search strategy of each database. Keywords used in the search include gout, cost-effectiveness, allopurinol, and febuxostat in MeSH and free-text forms. Screening of identified studies, data extraction, and quality assessment were done independently by 2 reviewers. The quality of studies was assessed based on Drummond Checklist. Finally, a qualitative analysis was done to analyze the results. Results: A total of 94 studies were identified through database search and the review of references. After screening the titles, abstracts, and full-texts, 6 economic evaluations were included in the review. The majority of the studies had been conducted in the US using the Markov model, within a 5-year horizon, and from the payer's perspective, with the quality of life as a measure of effectiveness. In most studies, the incremental cost-effectiveness ratios (ICERs) of febuxostat per quality-adjusted life year (QALY) were below the threshold (10 000$/QALY and 30 000€/QALY). Conclusion: Febuxostat has been shown to be more cost-effective than allopurinol in all treatment sequences in studies that have used uric acid levels as the measure of effectiveness. Furthermore, in studies with the quality of life as the measure of effectiveness, febuxostat has been shown to be very cost-effective as the second-line treatment.

The impact of adoption of a new urate-lowering agent on trends in utilization and cost in practice

OBJECTIVES

Changes in treatment choice of therapy and size of treated population that can lead to under- or overestimate of payer's budget are less likely to be reassured after reimbursement adoption of a new drug. The aim of this study was to evaluate the effects of febuxostat introduction and the modifications in its insurance coverage on the utilization and expenditure of urate-lowering therapy (ULT).

METHODS

Electronic medical records for adults patients prescribed any ULT during 2010-2015 was derived from the largest medical organization in Taiwan. Aggregated estimates of ULT use and costs were assessed per 3-month and per patient per month (PPPM). Factors associated with total ULT expenditure were assessed using a time series design with factored Autoregressive Integrated Moving Average (ARIMA) models.

RESULTS

ULT prevalent users increased 34.1% from 2010 to 2015 and a 123% increase in total ULT expenditure. Numbers on allopurinol and sulfinpyrazone both declined 31%, and on benzbromarone and febuxostat gradually increased to 38.21% and 22.89% of all users in 2015. Insurance payments PPPM ($4.44 to $9.22) and total monthly ULT cost ($32,946 to $ 85,732) growth more than doubled in 6 years, trend changes generated mostly by individuals switching to febuxostat.

CONCLUSIONS

ULT use moved to favor benzbromarone and febuxostat; greater expensive uptake for febuxostat led to a rapid rise in ULT cost. Marginal values of increasing access to febuxostat for asymptomatic hyperuricemia should be focus on future studies to facilitate drug prices negotiation and ensure appropriate ULT use.

Predictors of reaching a serum uric acid goal in patients with gout and treated with febuxostat

Purpose

Clinical guidelines recommend febuxostat as first-line pharmacologic urate-lowering therapy for patients with gout to achieve a goal serum uric acid (sUA) <6 mg/dL; however, little is known about other contributing factors. This study identified clinical characteristics of patients treated with febuxostat to develop and validate a predictive model for achieving a goal sUA.

Patients and methods

Patients with Humana Medicare or commercial insurance, diagnosed with gout and newly initiated on febuxostat (index date February 1, 2009 – December 31, 2013), were identified for a retrospective cohort study. Patients were followed for 365 days and the first valid sUA test result ≥120 days after index was retained. A stepwise logistic regression with backward elimination was estimated to model sUA goal attainment, and a linear model was estimated to model the impact of predictor variables on sUA level.

Results

The study sample (n=678) was divided into a development (training) dataset (n=453) and a validation (holdout) dataset (n=225). In the training sample, patients in the sUA <6 mg/dL group were on febuxostat for a longer time, were more adherent, and had a lower average base-line sUA level (all p<0.0001) vs patients in the sUA ≥6 mg/dL group. In the logistic model, febuxostat adherence (odds ratio [OR]=1.03, p<0.0001) and baseline sUA level (OR=0.84, p<0.0001) increased the odds of attaining sUA <6 mg/dL. In the linear regression model, increase in febuxostat adherence (p<0.0001), baseline sUA level (p<0.0001), advanced age (p=0.0021), and not having congestive heart failure (p<0.05) were associated with a reduction of sUA level. Pre-index allopurinol use was a marginally significant predictor of sUA level reduction (p=0.06).

Conclusions

Among febuxostat users diagnosed with gout in a real-world setting, adherence to febuxostat and lower baseline sUA level were the strongest predictors of attaining sUA goal. These findings may help clinicians to identify appropriate patients most likely to benefit from febuxostat treatment, and underscore the importance of medication adherence in this challenging patient population.

Risk of Febuxostat-Associated Myopathy in Patients with CKD

BACKGROUND AND OBJECTIVES

Febuxostat, a nonpurine xanthine oxidase inhibitor, is widely used to treat hyperuricemia. Although febuxostat-associated rhabdomyolysis was reported in some patients with CKD, the association between CKD and febuxostat-associated myopathy remains uncertain.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our retrospective cohort study included 1332 patients using febuxostat in Taipei Medical University-Wanfang Hospital from February of 2014 to January of 2016. The primary predictor was time-averaged eGFR as calculated by the equation proposed by the 2009 Chronic Kidney Disease Epidemiology Collaboration. The outcome was febuxostat-associated myopathy defined as elevated creatine kinase levels during febuxostat use that were not attributed to other muscular injuries.

RESULTS

The median duration of febuxostat use was 224 days (25th, 75th percentiles: 86, 441.5 days). Of 1332 study participants, 1222 (91.7%) had CKD; the median eGFR was 20.8 ml/min per 1.73 m2 (25th, 75th percentiles: 9.0, 35.4 ml/min per 1.73 m2). Forty-one of the participants had febuxostat-associated myopathy (3.2%). All patients with myopathy had CKD, and the incident rate was 0.013 (95% confidence interval, 0.01 to 0.02) events per 100 patient-days in patients with CKD. Of 41 patients with myopathy, 37 had myositis, and four had rhabdomyolysis. Myopathy resolved in 17 patients who withdrew from treatment and eight patients who continued febuxostat treatment. Among the evaluated predictors, multivariate analysis showed that only the lowest eGFR tertile was significantly associated with myopathy in febuxostat users. The odds ratio of the lowest eGFR tertile to the highest tertile was 4.21 (95% confidence interval, 1.7 to 10.43). This finding remained consistent among subgroups stratified by age, sex, diabetes status, coronary artery disease, and statin or fibrate use.

CONCLUSIONS

Patients with severely reduced eGFR had higher risk of myopathy with treatment of febuxostat. Regular monitoring of creatine kinase level is suggested for early detection of febuxostat-associated myopathy, particularly in patients with CKD.

Management of Gout and Hyperuricemia in CKD

Hyperuricemia and gout, the clinical manifestation of monosodium urate crystal deposition, are common in patients with chronic kidney disease (CKD). Although the presence of CKD poses additional challenges in gout management, effective urate lowering is possible for most patients with CKD. Initial doses of urate-lowering therapy are lower than in the non-CKD population, whereas incremental dose escalation is guided by regular monitoring of serum urate levels to reach the target level of <6mg/dL (or <5mg/dL for patients with tophi). Management of gout flares with presently available agents can be more challenging due to potential nephrotoxicity and/or contraindications in the setting of other common comorbid conditions. At present, asymptomatic hyperuricemia is not an indication for urate-lowering therapy, though emerging data may support a potential renoprotective effect.