For patients with rheumatoid arthritis (RA), the incidence rate (IR) of upper limb joint replacements has been decreasing since 2002, coinciding with the introduction of biologic disease-modifying antirheumatic drugs (bDMARDs), according to results published in Arthritis Research & Care.

The study included participants with incident RA from the Danish National Patient Register from 1996 to 2012 (n=18,654). Participants were matched by age, sex, and municipality with up to 10 general population controls.

The researchers calculated 5-year IRs using a composite outcome of any first joint replacement of the finger, wrist, elbow, or shoulder per 1000 person-years. They also used an interrupted time series analysis to determine trends and changes of the IR in the pre-bDMARD era (1996 to 2001) and the bDMARD era (2003 to 2012) with a 1-year lag period in 2002.

Within the first 5 years from the index date, 1.0% (n=193) of participants with RA had upper limb joint replacements.

From 1996 to 2001, the IR for joint replacements for participants with RA remained stable at 2.46 per 1000 person-years (95% CI, 1.96-2.96). From 2003 onward, the results indicated that the IR among participants with RA decreased -0.08 per 1000 person-years annually.

Among controls, the IR of joint replacements was 0.14 per 1000 person-years (95% CI, 0.07-0.21) in 1996. Unlike participants with RA, the IR for controls increased annually by 7% from 1996 to 2002. In 2003, the IR was 0.37 with annual increases that matched those of the earlier era.

“We found that the [5]-year IR of upper limb joint replacements among newly diagnosed [patients with RA] started to decrease following the introduction of bDMARDs,” the researchers wrote. “However, given the ecological design of the study, it is a possibility that other factors contributed to this finding.”

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Cordtz R, Hawley S, Prieto-Alhambra D, et al. Reduction in upper limb joint surgery among rheumatoid arthritis patients: an interrupted time series analysis using Danish health care registers [published online January 25, 2019]. Arthritis Care Res (Hoboken). doi:10.1002/acr.23835