Epidemiology of cardiac or orthopedic procedures in gout versus rheumatoid arthritis: a national time-trends study

AIMS: To examine the secular trends in the number and rates of in-hospital cardiac and orthopedic procedures in people with gout and rheumatoid arthritis (RA), and the United States (US) general population, from 1998 to 2014. METHODS: We examined the frequency of seven common cardiac and orthopedic procedures in hospitalized people with gout, RA, or the general population using the 1998–2014 US National Inpatient Sample (NIS). Poisson regression evaluated the differences in frequencies in 1998 versus 2014, between gout and RA, and within each cohort. RESULTS: Both in-hospital cardiac and orthopedic procedures increased in gout and RA with time, in contrast with declining cardiac procedures in the general US population. Cardiac procedures were significantly higher in gout versus RA in 1998 (59% higher) and 2014 (92% higher). The rate of cardiac procedures increased from 36.6 to 82.8 in gout and from 20.1 to 33.1 in RA per 100,000 NIS claims from 1998 to 2014. Orthopedic procedures became more common than cardiac procedures in gout and RA by 2014. In RA, the cardiac–orthopedic procedure volume difference was significant in 1998 and 2014. We noted no significant difference between cardiac versus orthopedic procedures in 1998 in gout, but the difference was significant in 2014. Orthopedic procedures in gout were significantly lower than RA in 1998 (33% lower), but were significantly higher than RA in 2014 (5% higher). CONCLUSION: Increasing in-hospital cardiac procedures in gout and RA contrasting with declining general US population rates indicated that optimal management of systemic inflammation and an early diagnosis of gout and RA are needed. The rate of increase in orthopedic procedures exceeded that in cardiac procedures. A much greater volume and rate of increase in common in-hospital cardiac and orthopedic procedures in gout compared to RA indicates that an aggressive approach to treat-to-target in gout is needed to potentially reduce the associated healthcare burden and cost. PLAIN LANGUAGE SUMMARY: Cardiac and orthopedic procedures rising faster for gout compared to rheumatoid arthritis in the United States We performed a national US study of the most common cardiac versus orthopedic procedures from 1998 to 2014. We found that over time, the number and the rate of cardiac procedures increased in people with gout (2.2-fold higher) or rheumatoid arthritis (1.6-fold higher). This was surprising, since during the same time, we noted a decrease in cardiac procedures in the general U.S. population. The rate of cardiac procedures in gout was 2.5-fold higher than that in rheumatoid arthritis, 82.8 vs. 33.1 per 100,000 NIS claims in 2014. Interestingly, orthopedic procedures were more common than cardiac procedures in both gout and RA in all periods. Also, the difference in the numbers of cardiac vs. orthopedic procedures increased over time in both gout and RA. Gout outpaced rheumatoid arthritis for both the total number and the rate of cardiac or orthopedic procedures over time. Therefore, our study provides an understanding of an increasing procedure burden in gout compared to rheumatoid arthritis, and to the general U.S. people with these conditions.