TNF inhibitor use only partly explains joint replacement reductions in RA
medwireNews: The role of tumor necrosis (TNF) inhibitors in reducing the need for joint replacements in patients with rheumatoid arthritis (RA) may be limited to total hip replacements in older patients and those with more severe disease, suggest trial findings.
“The use of biologic therapies has been routinely offered as an explanatory factor for the reduction in rates of joint replacement over recent years,” Samuel Hawley (University of Oxford, UK), who presented the findings at the EULAR 2018 meeting in Amsterdam, the Netherlands, told the press.
“Our study offers some support for this […], although our results also suggest additional factors are likely to be involved.”
He suggests that these other factors might include earlier diagnosis and treatment of RA and increased prescribing of conventional DMARDs.
The researchers compared the impact of TNF inhibitors and conventional DMARDs on the subsequent need for joint replacement in a patient-level analysis using a sample of 11,202 patients recruited into the British Society for Rheumatology Biologics Registry (2001–2016) for Rheumatoid Arthritis.
The patients initiated treatment with a TNF inhibitor (etanercept, infliximab, or adalimumab) or a conventional DMARD.
The team matched patients in the two groups according to a score for the likelihood of receiving a TNF inhibitor, which was based on factors including age, body mass index, duration of RA, clinical symptoms, comorbidities, and additional medications.
Overall, there was no significant difference between the two treatment groups in the risk for total hip or total knee replacement.
The rate of total hip replacement was 6.30 per 1000 patient─years among patients taking TNF inhibitors and 5.22 per 1000 patient─years among patients taking DMARDs, while for total knee replacement, the corresponding rates were 8.09 and 8.89 per 1000 patient─years.
It's suggestive that these patients may benefit from being initiated a TNF inhibitor
However, a significant 40% reduction in the need for total hip replacement was seen in patients over the age of 60 years, although there was no effect in younger patients. And the rate of total hip replacements was reduced by a nonsignificant 26% among patients with more severe disease (Disease Activity Score >5.1), who would be recommended for biologic use according to the UK National Institute for Health and Care Excellence recommendations.
Hawley commented that the findings could suggest a primary role for conventional DMARDs in explaining the falling rates of joint replacement, but adds that the “significant almost halving in the elderly patients of hip replacement does suggest that TNF [inhibition] does play a role.”
He also acknowledged that this was an observational study, which means that “[w]e can’t rule out that confounding and unobserved confounding or residual confounding remains, so we definitely need further studies to confirm these findings.”
By Lucy Piper
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