TNF inhibitors may slightly increase risk of developing severe extra-articular RA
Patients treated with tumour necrosis factor (TNF) inhibitors are marginally prone to develop severe extra-articular rheumatoid arthritis (ExRA), a study suggests. In addition, rheumatoid factor (RF)-positive patients with disabling disease of long duration are at an increased risk of developing severe ExRA.
Researchers recruited a dynamic community-based cohort of patients with RA (n=1,977) to assess whether treatment with TNF inhibitors affected the risk of developing severe ExRA manifestations, as well as to study potential predictors for developing ExRA. They reviewed clinical records and identified cases of severe ExRA. Information on exposure to TNF inhibitors was obtained from a regional register.
Analysis of exposure to TNF inhibitors was done in a time-dependent fashion. Additionally, researchers compared the incidence of severe ExRA in exposed patients with the incidence in those who were unexposed. Cox regression models were used to evaluate possible predictors of severe ExRA.
A total of 17 patients had new onset of severe ExRA during treatment with TNF inhibitors in 2,400 person-years at risk (0.71/100; 95 percent CI, 0.41 to 1.13) compared with 104 in 15,599 person-years (0.67/100; 0.54 to 0.81) in those without TNF inhibitors, corresponding to an incidence rate ratio of 1.06 (0.60 to 1.78).
Anti-TNF‒treated patients had a hazard ratio for ExRA of 1.21 (1.02 to 1.43), adjusted for age and sex; the findings were similar in models adjusted for time-dependent Health Assessment Questionnaire and propensity for anti-TNF treatment.
The predictors for ExRA were male sex, positive RF, long disease duration and greater disability, according to researchers.