OP0162-HPR Estimating health-related quality of life for gout patients: a post-hoc analysis of utilities from the clear trials
Authors: F. Pérez-Ruiz, A. So, P. Kandaswamy, R. Karra, K. Kelton, S. Perk, T. Bardin
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Prior studies of health-related quality of life (HRQoL) in gout patients have shown significant disutilities associated with flares and tophi or serum uric acid (sUA).<sup>1 2</sup> However, no prior study has explored the simultaneous impact of all three aspects of gout severity. <h3>Objectives</h3> Estimate the impact of gout flares, tophi, and sUA levels on HRQoL through post-hoc analysis of SF-36 data collected in two randomised, double-blind, placebo-controlled Phase 3 studies of urate lowering therapies in gout patients (CLEAR 1 and CLEAR 2).<sup>3 4</sup> <h3>Methods</h3> Linear regression analysis was used to estimate the effects of patient and disease characteristics on SF-6D scores at month 6 and month 12. Multiple regression methods and out-of-sample testing were used to select the final model from covariates representing tophus burden, the number of flares during each six-month period, serum urate levels, baseline characteristics, and comorbidities. Predicted mean utility scores were calculated by evaluating the model at the mean values of the covariates (excluding location-specific covariates) in the pooled CLEAR 1 and CLEAR 2 intent-to-treat population.<sup>3 4</sup> <h3>Results</h3> The final regression model (table 1) includes significant disutilities associated with the presence of tophi at screening (0.0418; SE: 0.0073; p&lt;0.001), the number of gout flares (0.0036 per flare; SE: 0.0005; p&lt;0.001), and median sUA on-treatment (0.0083 per mg/dL in excess of 6 mg/dL; SE: 0.0031; p=0.007). The predicted mean utility scores for patients with zero flares and no tophi are 0.7718 for sUA &lt;6 mg/dL; 0.7552 for sUA 6 to &lt;8 mg/dL; 0.7386 for sUA 8 to &lt;10 mg/dL; and 0.7220 for sUA ≥10 mg/dL. R<sup>2</sup>: 0.1788; Adjusted R<sup>2</sup>: 0.1730; Residual standard error: 0.1217 on 1857 degrees of freedom. <sup>†</sup>Baseline characteristics. <sup>‡</sup>Median sUA on-treatment. Abbreviations: SE, standard error; SF-6D, Short form 6D questionnaire; sUA, serum uric acid. <h3>Conclusions</h3> The present analysis is unique in that it explored the simultaneous effects of flares, tophi, and sUA on HRQoL. The results indicate that high sUA levels are associated with significant disutility when controlling for the effects of flares, tophi, and other patient covariates. The clinical rationale is that uncontrolled sUA creates a state of chronic inflammation, contributing to underlying ill health in addition to its effects on flares, tophi, and comorbidities. <h3>References</h3> [1] Beard SM, et al. Eur J Health Econ2014;15(5):453–63. [2] Khanna PP, et al. Health Qual Life Outcomes2012;10:117. [3] Data on file. Clinical Study Report RDEA594–301. Ardea Biosciences, Inc.; 2014. [4] Data on file. Clinical Study Report RDEA594–302. Ardea Biosciences, Inc.; 2014. <h3>Disclosure of Interest</h3> F. Pérez-Ruiz Grant/research support from: Spanish Society of Rheumatology, Cruces Hospital Rheumatology Association, Consultant for: Grünenthal, Menarini, Speakers bureau: Grünenthal, Menarini, A. So Consultant for: Grünenthal, Sobi, Speakers bureau: Grünenthal, Sobi, P. Kandaswamy Employee of: Grünenthal, R. Karra Employee of: Grünenthal, K. Kelton Employee of: Medical Decision Modelling, a contractor to Grünenthal, S. Perk Employee of: Medical Decision Modelling, a contractor to Grünenthal, T. Bardin Consultant for: Grünenthal, AstraZenaca, Menarini, Ipsen, Sobi, Novartis