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09-05-2019 | Rheumatology | News | Article

RA patients continue to have excess risk for joint replacement

medwireNews: Approximately one in five people diagnosed with rheumatoid arthritis (RA) will need a knee or hip replacement during their remaining lifetime, shows an analysis of data from the UK’s National Health Service (NHS).

By comparison, the lifetime risks among 50-year-old men and women from the UK general population have previously been estimated to be 8% and 11%, respectively, for knee replacement, and 7% and 11%, respectively, for hip replacement, explain Rafael Pinedo-Villaneuva (University of Oxford, UK) and co-investigators.

Therefore, “despite the improvement in the diagnosis and treatment of the disease, RA is still associated with a lifetime risk of both knee and hip replacement approximately double that of the general population,” the researchers say.

The analysis of routinely collected data from 13,961 individuals diagnosed with RA (median age 64 years, 68% women) between 1997 and 2014 showed that the 15-year cumulative incidence of knee replacement was 9.69%, while the incidence of hip replacement was 7.69%.

The researchers estimated that for the average patient profile – a nonsmoking woman aged 64 years with no comorbidities, a BMI of 27 kg/m2, in the top socioeconomic quintile – the lifetime risks for knee and hip replacement were 22% and 17%, respectively.

Younger patients had a higher lifetime risk whereas older patients had a lower risk, apparently driven by the effect of age on mortality, and thus time at risk.

Sex, socioeconomic status, and smoking status had no significant impact on risk but patients with comorbidities had lower lifetime risks for both surgeries relative to those without, which Pinedo-Villaneuva and team say is “mainly due to the effect of comorbidities on risk of mortality.”

By contrast, point estimates indicated that there was a positive linear association between BMI at diagnosis and lifetime risks, particularly for knee replacement.

The researchers also found that timing to knee and hip replacement varied by age. “In general, risks were closer to being constant over time for younger patients whereas risks peaked shortly after diagnosis for older patients” Pinedo-Villaneuva and co-authors write in Rheumatology.

And they conclude that their findings “allow for a better understanding of long-term prognosis and healthcare resource use, and highlight the importance of timely diagnosis and effective treatment [of RA].”

By Laura Cowen

medwireNews is an independent medical news service provided by Springer Healthcare. © 2019 Springer Healthcare part of the Springer Nature group

Rheumatology 2019; doi:10.1093/rheumatology/kez143

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