Rheumatoid arthritis infection risk predicted by RABBIT

By Lynda Williams

The RABBIT risk score can predict the likelihood of serious infection in rheumatoid arthritis (RA) patients using tumor necrosis factor-alpha (TNF-α) inhibitors and disease-modifying antirheumatic drugs (DMARDs), research confirms.

"This tool could help rheumatologists identify at-risk patients and avoid treatment combinations that have a higher risk of infectious complications," said Angela Zink (German Rheumatism Research Centre, Berlin) in a press release.

"This could also help reducing costs associated with treating the infections."

The risk score, devised using data from the German registry for observation of biologic therapy in RA patients (RABBIT) between 2001 and 2006, stratifies patients as high risk for serious infection on the basis of chronic lung disease, chronic renal disease, and age over 60 years.

The team tested the RABBIT risk score using a second set of RABBIT data from 2009 onwards for 1327 RA patients using TNF-α inhibitors and 1276 patients using DMARDs.

Analysis revealed very good agreement between the number of serious infections predicted by the RABBIT risk score, and the actual number of events, the researchers reported at the European League Against Rheumatism Annual Congress of Rheumatology, held in Berlin, Germany.

For patients with no risk factors who were using TNF-α inhibitors, the expected and actual rates were 3.0 and 3.2 events per 100 patient‑years, respectively. The corresponding rates were 1.5 and 1.3 per 100 patient‑years for such patients using DMARDs.

The expected and actual rates were also similar for patients with one or more risk factor, at 4.3 and 5.2 cases per 100 patient‑years for those using TNF-α inhibitors, and 1.9 and 1.7 for those using DMARDs.

The rates rose again when glucocorticoids (≥7.5 mg/day prednisolone equivalent) were added to TNF-α inhibitor treatment (10.0 and 9.4 per 100 patient‑years), or DMARD therapy (5.0 and 7.9 per 100 patient‑years).

"The results of our study validate the RABBIT Risk Score as a useful tool to help identify RA patients at high risk of developing infections when treated with anti-TNFs or DMARDs," Zink concluded.

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