Background/Purpose: Elevated intraocular levels of these pro-inflammatory cytokines and systemic levels of C-reactive protein are seen in uveitis, which leads to 30,000 new cases of legal blindness annually in the U.S. Limited epidemiological information is available for risk factors for uveitis. Our objective was to assess whether gout in the elderly is associated with a risk of incident uveitis.

Methods: We used the 5% Medicare claims data from 2006-2012 for this cohort study. Gout was identified by the presence of two claims for gout at least 4 weeks apart, with International Classification of Diseases, ninth revision, common modification (ICD-9-CM) code of 274.xx. Study outcome was incident uveitis, identified by two claims for uveitis with an ICD-9-CM code of 364.xx, at least 4 weeks apart and an absence of uveitis claims in the baseline 365-day period, a valid approach. We used multivariable-adjusted Cox proportional hazard models to assess the association of gout with incident uveitis, adjusting for potential confounders/covariates including demographics (age, race, gender), comorbidities (Charlson-Romano comorbidity index), and medications commonly used for cardiac diseases (statins, beta-blockers, diuretics, and angiotensin converting enzyme (ACE)-inhibitors) and gout (allopurinol and febuxostat; Model 1).  

Results: We found 8,459 incident uveitis cases in our cohort of 1,240,681 Medicare recipients, 464 in people with and 7,995 in people without gout, leading to respective incidence rates of 179 and 93 per 100,000 person-years. The mean [standard deviation (SD)] time from gout diagnosis to the new diagnosis of uveitis was 804 days [SD, 572] (median, 694 days; interquartile range, 329, 1190 days). Compared to people without incident uveitis, people with uveitis were significantly more likely to be older, female, Black and have higher medical comorbidity. After multivariable-adjustment (model 1), gout was associated with 1.53-fold higher hazard of uveitis (95% confidence interval (CI), 1.39, 1.69; p<0.0001) (Table 1), as were older age, female gender, Black or other race/ethnicity, and comorbidities including diabetes, chronic pulmonary disease, connective tissue disease or any tumor/leukemia/lymphoma (Table 1). Sensitivity analysis that replaced continuous Charlson-Romano index with categorized scale (Model 2) or individual comorbidities plus hyperlipidemia, coronary artery disease and hypertension (Model 3) confirmed the findings from the main analyses with minimal attenuation of hazard ratios.

Conclusion: Gout was independently associated with 1.5-fold higher risk of uveitis in the older individuals after adjustment for demographics, comorbidity and medications, and the risk could be between 1.4 to 1.9-fold higher risk. Future studies need to confirm this finding and evaluate the underlying mechanism of this novel association.