Arthritis onset since biological disease-modifying anti-rheumatic drugs (bDMARDs) were introduced is associated with a significant reduction in rate of total hip and knee arthroplasty (THA/TKA) in patients with rheumatoid arthritis (RA) but not in osteoarthritis (OA), according to study findings published in Rheumatology.
Investigators compared time trends and levels of total joint arthroplasty (TJA) rates in patients with RA and OA who were diagnosed in the pre-bDMARDs (1995-2001) and post-bDMARDs (2003-2007) eras. The adjusted 8-year incidence of TJA estimated for RA/OA cohorts diagnosed 5 years after bDMARDs introduction was compared with expected rates assuming no bDMARDs introduction, based on extrapolation of pre-bDMARDs trends.
A total of 60,227 incident patients with RA (mean [SD] age at diagnosis 59.1 [15.91] years; 67% women) and 288,260 incident patients with OA (mean [SD] age at diagnosis 62.7 [14.46] years; 59% women) were diagnosed between 1995 and 2007.
For patients with RA, the 8-year incidence of THA increased with each successive year of RA onset in the pre-period with a slope of 0.21 (95% CI, 0.08 to 0.35), but beginning in 2003 the rate decreased with a slope of –0.31 (95% CI, –0.54 to –0.09), the researchers found. The overall crude and adjusted differences in slopes between the post- and pre-periods were –0.53 (95% CI, –0.79 to –0.27; P = .0007) and –0.49 (95% CI, –0.74 to –0.23; P = .0015), respectively.
In OA patients, the THA incidence increased slightly in the pre-period with a slope of 0.10 (95% CI, 0.04 to 0.16), and beginning in 2003 the rate increased further with a slope of 0.34 (95% CI, 0.21 to 0.48). The crude and adjusted differences in slopes between the post- and pre-periods were 0.25 (95% CI, 0.08 to 0.41; P = .0077) and 0.40 (95% CI, 0.15 to 0.65; P = .0061), respectively.
The 8-year TKA incidence in RA patients increased with a slope of 0.25 (95% CI, 0.10 to 0.41) with increasing year of RA onset before 2002, but it decreased afterward with a slope of –0.17 (95% CI, –0.29 to –0.04). The overall crude and adjusted differences in slopes between the post- and pre-periods were –0.42 (95% CI, –0.64 to –0.21; P = .001) and –0.36 (95% CI, –0.57 to –0.16; P = .0028), respectively.
The TKA incidence in OA patients increased with a slope of 0.24 (95% CI, 0.16 to 0.32) in the pre-period, and beginning in 2003 it increased further with a slope of 0.63 (95% CI, 0.46 to 0.80). The overall crude and adjusted differences in slopes between the post- and pre-periods were 0.39 (95% CI, 0.22 to 0.56; P = .0002) and 0.54 (95% CI, 0.30 to 0.78; P = .0004), respectively.
At 5 years after bDMARDs introduction, THA incidence declined by 26.9% (–2.05/7.63) in RA and increased by 11.7% (1.48/12.60) in OA. TKA incidence was reduced by 12.6% (–1.13/8.96) in RA and increased by 16.6% (2.10/12.64) in OA.
Among several study limitations, the findings may be susceptible to changes in TJA risk factors or other interventions that may have occurred concomitantly with the introduction of bDMARDs, the researchers noted. Also, the lack of clinical or radiographic information limits the ability to accurately determine the reason for TJAs and to understand the underlying mechanisms of bDMARDs’ effects.
“Our study has shown a significant reduction in TJA incidence among RA patients after the introduction of bDMARDs, and this reflects a significant improvement in RA treatment during the biological era,” stated the study authors.
Zhou VY, Lacaille D, Lu N, et al. Has the incidence of total joint arthroplasty in rheumatoid arthritis decreased in the era of biologics use? A population-based cohort study. Rheumatology (Oxford). Published online August 9, 2021. doi:10.1093/rheumatology/keab643