Background Gout is a common inflammatory arthritis and its worldwide prevalence is increasing. EULAR and American College of Rheumatology guidelines recommend a target sUA <6 mg/dL, with a target of <5 mg/dL in those with more severe symptomatic disease. Patients with significant crystal burden are assumed to have higher humanistic and economic burden of illness.
Objectives To describe patient and treatment characteristics and resource utilization in gout patients with and without tophi.
Methods Data were assessed from a survey of physicians and in-depth patient chart audits from France, Germany, Italy, Spain and the UK. Severity of gout was measured by physician global assessment. Flares, organ/joint damage and tophi were abstracted from the clinical chart. Type/dose of xanthine oxidase inhibitor, length of current treatment, physician type and patient sociodemographic factors were identified. Anonymized patients were included. Patients with a diagnosis of tophaceous gout were compared to all other gout (non-tophaceous) patients. Demographic characteristics and comorbidities, sUA levels, and use of colchicine for acute flares during the 12-month study period were compared using chi-square or Fisher's exact tests.
Results Of the 1260 patients identified with gout, 327 (25.95%) had physician-confirmed tophaceous gout and 933 (74.05%) had non-tophaceous gout. Patients with tophi were older (62.3 vs 58.6 years old; p<0.001), had gout for a slightly longer period of time (2.8 vs 2.5 years; p<0.001), reported more flares (3.4 vs 1.7 per year; p<0.001), and were more likely to have joint damage (45.3% vs 10.5%; p<0.001). There were significantly higher levels of comorbidities in patients with tophi including cardiovascular disease (p<0.001), chronic obstructive pulmonary disease (p<0.001), congestive heart failure (p<0.001), diabetes (p=0.011), depression (p=0.001), hypertension (p<0.001), osteoarthritis (p<0.001) and Stage III (p<0.001) and Stage V (p=0.016) chronic kidney disease. Patients with tophi were more likely to be treated with a urate-lowering therapy (87.5% vs 78.6%; p<0.001). Patients with tophi were less likely to be using allopurinol (56% vs 68%; p<0.001) and more likely to be treated with febuxostat (22.9% vs 7.9%). There was no difference in the use of NSAIDs; however, patients with tophi were more likely to take colchicine (46.5% vs 33.7%; p<0.001) and steroids (27% vs 10%; p<0.001). Patients with tophi were less likely to reach the ideal treatment goal of sUA targets of <6 mg/dL and no flares (17% vs 27%; p<0.001) or <5 mg/dL and no flares (6% vs 14%; p<0.001). Patients with tophi made more gout-related office visits (6.07 vs 4.51; p<0.001) and a greater proportion made ≥1 gout-related emergency visit (27.2% vs 9.5%; p<0.001), hospitalization (12.8% vs 3%; p<0.001) or had a gout- related surgery (3.1 vs 1.2; p=0.022).
Conclusions Patients with tophaceous gout have significantly greater burden of disease and greater frequency of comorbidities than patients with non-tophaceous gout. Preventing the development of tophi or resolving crystal burden by treating to guideline targets remains a rarely achieved goal for patients with and without tophi.
Acknowledgement This study was funded by AstraZeneca. Editorial support was provided by PAREXEL and funded by AstraZeneca.
Disclosure of Interest P. Khanna Grant/research support from: AstraZeneca, E. Tafesse Employee of: AstraZeneca, S. Baumgartner Employee of: Ardea Biosciences, a member of the AstraZeneca Group, A. Walker Employee of: AstraZeneca, R. Morlock Employee of: Ardea Biosciences, a member of the AstraZeneca Group