medwireNews: A longer duration of treatment with tumor necrosis factor (TNF) inhibitors is associated with a reduced risk for hand osteoarthritis (OA) progression in the distal interphalangeal (DIP) joints after 10 years, results of an observational study suggest.
Marieke Loef (Leiden University Medical Centre, the Netherlands) and fellow researchers analyzed 10-year clinical and radiographic follow-up data from 262 patients with rheumatoid arthritis (RA) who participated in the BeSt trial, 55% of whom also had hand OA at baseline. In all, 63% of patients with OA were treated with TNF-α inhibitors for a median of 47 months.
Using a multivariate regression analysis, the team found that each additional month of TNF inhibitor treatment was associated with a 1.3% reduction in the relative risk for progressive OA in the DIP joints after adjustment for factors including age, sex, and disease duration, where progression was defined as an increase in osteophyte score of at least 1 point in one joint over 10 years regardless of the presence of OA at baseline.
However, the duration of TNF inhibitor treatment was not significantly associated with OA progression in the proximal interphalangeal (PIP) joints, or in the DIP and PIP joints combined. There was also no significant association between treatment duration and incidental OA among those who did not have OA at baseline.
Describing the differences in the association between TNF inhibitor treatment and OA progression in DIP and PIP joints as “difficult to interpret,” the researchers hypothesize that “[i]n light of the studied population consisting of RA patients, OA in these two joint categories may represent two distinct disease entities.”
They add that “although a strict distinction cannot be made, OA in the DIP joints will mostly represent primary OA, while OA in the PIP joints could be either primary or secondary OA.”
Discussing the limitations of their study, Loef and team caution that because the BeSt trial was “a randomized trial primarily designed to investigate targeted treatment in RA patients,” the results may not be generalizable to other patient populations. They also note that the observed effect sizes were “small.”
Nevertheless, the study authors conclude in Rheumatology: “Our results suggest the influence of TNF-α in hand OA pathogenesis.”
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