Serum uric acid levels and the risk of flares among gout patients in a US managed care setting

Abstract

Objective: Serum uric acid (sUA) levels are causally associated with the risk of gout flares. Our aim was to assess the magnitude of the association and time to first flare among patients in a managed care setting.

Research design and methods: We conducted a retrospective cohort study using administrative claims data from a large US health plan. Patients were required to have evidence of gout based on medical and pharmacy claims between January 2009 and April 2012. The 12 months prior to the index gout claim were used to assess baseline sUA levels; risk of gout flares, stratified by baseline sUA levels, was examined for 2 years post-index. Risk of flare was modeled with Cox proportional hazards; time to first flare was assessed by Kaplan–Meier.

Results: We identified 18,008 patients with gout and available baseline SUA levels (mg/dL). The hazard ratios for the risk of gout flares compared with sUA <5.0 were: 1.17 for sUA 5.0 to <6.0; 1.69 for sUA 6.0 to <7.0; 2.16 for sUA 7.0 to <8.0; 2.87 for sUA 8.0 to <9.0; and 3.85 for sUA ≥9.0 (all p < .001 except for sUA 5.0 to <6.0 cohort). The time to first flare was shorter for cohorts with higher baseline sUA levels.

Conclusion: These findings confirm that higher sUA levels are associated with an increased risk of gout flares in a dose–response manner over 2 years. This data supports the need to treat to sUA target levels as recommended by recent gout care guidelines. Claims-based algorithms were used to identify gout flares; although this would not be expected to influence estimates of risk by sUA level, there may have been over- or under-estimation of the incidence of flares.

Keywords:

• Flares
• gout
• managed care
• retrospective
• serum uric acid

Transparency

Declaration of funding

This study was sponsored by Takeda Pharmaceuticals International Inc.

Declaration of financial/other relationships

A.S. has disclosed that she is an employee of Takeda Pharmaceuticals International Inc. E.K.B. and S.K. have disclosed that they are employees of Optum Inc. Optum received research funding from Takeda Pharmaceuticals International Inc. to complete this study.

Acknowledgments

Jesse Potash and Sarah Peirce-Sandner, Optum Inc., provided medical writing assistance. Lynn Wacha, Optum Inc., provided programming support. The authors thank Dr. Hyon Choi for his research consulting for the project.

CMRO peer reviewer 1 has disclosed that he is a consultant to SOBI, Aequus, AstraZeneca, Revive, Horizon, Selecta, Relburn and Proteothra. Peer reviewer 2 has no relevant financial relationships to disclose.