February 28, 2019
2 min read

DMARD introduction coincides with decrease in upper limb joint replacement in RA

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The incidence rate of upper limb joint replacements among patients with rheumatoid arthritis decreased from 2002 onward, coinciding with the introduction of biological disease-modifying antirheumatic drugs, although other factors may have contributed, according to findings published in Arthritis Care & Research.

“In patients with rheumatoid arthritis (RA), joint replacement surgery is considered a proxy for end-stage or severe joint damage,” René Cordtz, MD, of the Center for Rheumatology and Spine Diseases, Rigshospitalet–Gentofte, in Copenhagen, Denmark, and colleagues wrote. “The introduction of biological DMARDs in the late 1990s and early 2000s has expanded the treatment repertoire and increased the chances of more favorable clinical and radiographic outcomes for RA patients. Whether the improved clinical outcomes observed with [biological] DMARDs have resulted in lower rates of upper limb joint surgery is less clear.”

To determine the impact that the introduction of biological DMARDs had on the incidence rate of upper limb replacement procedures among newly diagnosed patients with RA, Cordtz and colleagues studied 1996 to 2012 data from the Danish National Patient Register. After identifying 18,654 patients with RA, the researchers matched each with as many as 10 general-population controls based on age, sex and municipality.

The researchers calculated the 5-year incidence rates per 1,000 person-years of a composite outcome of any first replacement of a finger, wrist, elbow or shoulder joint, standardizing for age and sex. In addition, Cordtz and colleagues conducted an interrupted time series analysis to evaluate incidence trends during the time periods prior to biologic DMARDs, specifically 1996 to 2001, and after their introduction, from 2003 to 2012, allowing for a 1-year lag period in 2002.

According to the researchers, the incidence rate of joint replacements in patients with RA was stable at 2.46 per 1,000 patient-years (95% CI, 1.962.96) during the 1996 to 2001 period, but began to decrease starting in 2002, with incidence rates of –0.08 per 1,000 patient-years annually (95% CI, –0.2 to 0.02). Incidence rates among the general-population controls was one in 17 in 1996, and increased continuously throughout the study period.

“We found that the five-year [incidence rate] of upper limb joint replacements among newly diagnosed RA patients started to decrease following the introduction of [biological] DMARDs,” Cordtz and colleagues wrote. “However, given the ecological design of the study, it is a possibility that other factors contributed to this finding. In 1996, the [incidence rate] of upper limb joint replacements was 17-fold higher among RA patients compared to non-RA individuals. In 2012, it was only 3.5 times higher. In context, our study supports previous reports of improved outcomes in newly diagnosed RA patients.” – by Jason Laday

Disclosure: Cordtz reports no relevant financial disclosures. Please see the study for all other relevant financial disclosures.