Background/Purpose: Gout is a common acute and potentially progressive disease affecting approximately 8 million Americans. Hyperuricemia (serum urate levels [sUA] >6.8mg/dL) is a major pathogenic factor in gout. Urate-lowering therapy (ULT), aimed at maintaining sUA in the range <6.0 mg/dL, is the commonly recommended goal for managing the hyperuricemia in gout, with allopurinol (ALLO) being the first line therapy in the majority of patients. ALLO, however, has many limitations, including intolerance and dose-limitations in renally compromised patients. Febuxostat (FEB) is another xanthine oxidase inhibitor approved by the FDA in 2009 with favorable safety and tolerability profiles. Our aim was to compare baseline demographics and comorbid characteristics of gout patients receiving ALLO and FEB.

Methods: Retrospective cohort study using a U.S. ambulatory care-based electronic medical record database with health records of primary care pts. Pts ≥18 years with a prescription for ALLO or FEB from April 1, 2009 to July 31, 2011 and with 13+ months of database activity prior to and a minimum of 6 months of activity after index date were included. Pts prescribed ALLO or FEB with diagnosis of neoplasm or with prescriptions for 2 or more ULTs on index date were excluded. Baseline pt characteristics (age, gender, race, and payer status); gout disease features (duration, sUA, presence of tophi); and comorbidities, (obtained from clinical history and/or body mass index, blood pressure, fasting plasma glucose, estimated creatinine clearance (eCrCL), smoking status, and alcohol use) were recorded. Comorbid status was summarized by Deyo-modified Charlson Comorbidity Index (CCI) and concomitant medication variables. Descriptive statistics, including mean and standard deviation for continuous variables, counts and proportions for categorical variables were utilized to describe the characteristics of ALLO and FEB cohorts. T-tests were used for continuous variables and chi-square tests for categorical variables.

Results: The study identified 35,404 ALLO-treated pts (mean age 63.2(±12.1) years; 77% male) and 2,837 FEB pts (mean age 61.7(±13.1) years; 73% male). Mean baseline sUA was significantly higher in FEB than ALLO pts (8.28 mg/dL vs 6.93 mg/dL, p<0.0001) and more FEB pts had sUA ≥ 9.0 mg/dL (32.7% vs 12.9%, p<.0001). Majority of ALLO-treated pts (57.1%) were receiving 300mg/day and 37.3% were receiving 100mg/day. FEB-treated pts had greater numbers of comorbidities (CCI ≥3, 22.1% vs 17.05 %, p<0.0001), and higher mean CCI scores (1.65 vs 1.51, p=0.0002) than ALLO pts, and more severe renal disease (eCrCL <60 29.8.0% vs 19.4%, p<.0001), presence of tophi (2.22% vs 0.39%), heart failure (5.11% vs 3.01%, p<0.0001), hypertension (HTN) (18.26% vs 16.29%, p=0.0066), and coronary artery disease (CAD) (8.35% vs 7.05%, p=.0097) were also more common in FEB pts than in those receiving ALLO.

Conclusion: A real-world comparison of utilization patterns of ALLO and FEB, shows that ALLO remains the ULT most often used in patients with gout, while FEB is being used in more difficult to treat patients, including those with higher baseline sUA levels and with commonly associated co-morbidities.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/comparing-clinical-characteristics-and-comorbidities-of-gout-patients-treated-with-allopurinol-or-febuxostat/