Background/Purpose: Coexistent RA and gout were previously believed to be exceedingly rare due to several hypothesized mechanisms encompassing inhibition of crystal formation, deposition, and activation. While now well recognized to coexist, the influence of gout on RA disease measures, medication selection, and long-term outcomes remains unknown. We aimed to assess the associations of comorbid gout with RA measures, treatments, and outcomes.

Methods: Participants in a longitudinal observational cohort of US veterans with RA fulfilling the 1987 ACR criteria were screened for gout within national administrative data for 12 months prior to enrollment using the Healthcare Cost and Utilization Project Clinical Classification Software and within the registry database for urate lowering medications or colchicine. Gout was confirmed by the presence of a physician diagnosis of gout in electronic medical records. Patient characteristics, RA measures, and medications were obtained from the registry, and vital status was determined using linkage with the National Death Index. We compared baseline characteristics using chi-square and independent t-tests. We studied the associations of gout with RA disease characteristics and medication use using multivariable logistic and linear regression models and all-cause mortality with multivariable Cox proportional hazards regression models.

Results: In 2,068 participants (91% male), we identified 107 with coexistent gout (5.2%). At enrollment, RA & gout was associated with older age, higher body mass index, comorbidity, swollen joint count, functional disability, and less frequent shared epitope alleles and NSAID use (Table 1). There were non-significant trends toward less seropositivity and lower autoantibody titers in RA & gout. Odds of ever receiving prednisone, DMARDs, and biologics did not differ between RA and RA & gout (all p>0.54). The odds of ever achieving DAS28 (OR 0.72, 95% CI 0.48-1.07, p=0.11) or CDAI (OR 0.67, 95% CI 0.41-1.11, p=0.12) remission were less common in RA & gout vs. RA alone, although these associations were not statistically significant. Gout was not associated with all-cause mortality (multivariable HR 1.14, 95% CI 0.72-1.80, p=0.57) among RA patients.

Conclusion: To our knowledge, this is among the largest studies of coexistent RA and gout described to date. The male predominance, older age, and high comorbidity of participants in the cohort make it an ideal setting for the study of coexistent RA and gout. Gout is associated with demographic and genetic parameters, higher comorbidity burden, and RA measures including higher swollen joint counts and functional disability. These findings highlight the need for identification and treatment of comorbid gout and further study to better understand the mechanisms underpinning these differences and the potential impact that gout therapies might have on RA outcomes.

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