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Serum Urate Levels and Gout Flares: Analysis From Managed Care Data

Sarawate, Chaitanya A. MS*; Patel, Pankaj A. MS, PharmD†; Schumacher, H Ralph MD‡; Yang, Wenya MPA*; Brewer, Kathleen K. MS, PhD*; Bakst, Alan W. MBA, PharmD†

JCR: Journal of Clinical Rheumatology:
doi: 10.1097/01.rhu.0000209882.50228.9f
Original Article
Abstract

Background: The desired serum urate level (SUA) for prevention of gout attacks is widely recommended to be in the subsaturating range, <6.0 mg/dL.

Objectives: The objectives of this study were to evaluate attainment of this target SUA among gout patients on allopurinol in a naturalistic setting and to assess its impact on gout flare risk.

Methods: This was a retrospective, observational study in a southeastern U.S. managed care organization of approximately 2.2 million members. The first gout claim/prescription within the intake period (January 1, 2000–December 31, 2002) was the index date. Included patients had ≥2 visits with gout International Classification of Diseases, 9th Revision code (274.xx) or ≥1 pharmacy script(s) for allopurinol, colchicine, probenecid, or sulfinpyrazone. Excluded patients were <18 years and/or did not have a 1-year continuous eligibility pre-/postindex date. Gout flares were defined by office/emergency room visit with gout or joint pain code(s) and ≥1 of the following within 7 days of the visit: intraarticular aspiration/injection, joint fluid microscopy, or pharmacy claim for nonsteroidal antiinflammatory drug, colchicine, corticosteroid, or ACTH. Multivariable regression analyses were conducted to evaluate gout flare risk/rate and association with target SUA.

Results: Approximately 40% of 5942 gout patients identified used allopurinol postindex. Among allopurinol users with pre-/postindex SUA data (n = 162), mean SUA was lowered from 8.7 mg/dL to 7.1 mg/dL; reduction was significant (P < 0.001). Among allopurinol users who did not have SUA <6.0 mg/dL preindex (n = 147), only 25% reached target levels during postindex. Despite pharmacotherapy, patients with nontarget levels were 59% more likely to flare than those at target. Allopurinol users who were not at target were 75% more likely to flare.

Conclusion: The failure of allopurinol users to achieve target SUA levels of <6.0 mg/dL may be attributed to lack of awareness of optimal SUA, allopurinol dosing, compliance, and efficacy. Patients who did not achieve target SUA were at increased flare risk.

In Brief

Data from a managed care cohort demonstrate that many patients with gout do not reach the proposed target urate of &amp;#x003C;6 mg/dL and have more frequent flares than those who do reach the target. Allopurinol as prescribed with doses rarely above 300 mg was not as effective as anticipated.

Author Information

From *HealthCore, Inc., Wilmington, Delaware; †TAP Pharmaceutical Products, Inc., Lake Forest, Illinois; and the ‡University of Pennsylvania and Department of Veterans Affairs Medical Center, Philadelphia, Pennsylvania.

This study was funded by a grant from TAP Pharmaceutical Products, Inc. Abstracts of this data were presented at the International Society for Pharmacoeconomics and Outcomes Research 10th Annual Meeting, Washington, DC, May 14–16, 2005.

Reprints: Chaitanya Sarawate, MS, Manager, Analytics, Health Outcomes Research, HealthCore, Inc., 800 Delaware Ave., Fifth Floor, Wilmington, DE 19801-1366. E-mail: csarawate@healthcore.com

© 2006 Lippincott Williams & Wilkins, Inc.