Patients with ankylosing spondylitis treated with anti-rheumatic drugs or anti-tumor necrosis therapy are not more likely to develop infections compared to non-users, a study shows.

The study, “ Use of disease-modifying anti-rheumatic or anti-tumour necrosis factor drugs and risk of hospitalized infection in ankylosing spondylitis ,” was published in the Scandinavian Journal of Rheumatology.

Because ankylosing spondylitis (AS) is a chronic inflammatory disorder, initial therapy is based on non-steroidal anti-inflammatory drugs (NSAIDs).

Traditional non-biological disease-modifying anti-rheumatic drugs (DMARDs), which include sulfasalazine (trade name Azulfidine, among others) and methotrexate (trade names Trexall, Rheumatrex, among others), have shown limited benefits for AS patients.

One of the more recently investigated therapies — anti-tumor necrosis factor-alpha (anti-TNF-alpha) therapy — may provide substantial benefits and its use has been recommended for management of AS.

There are a variety of anti-TNF agents available, including infliximab (Remicade), adalimumab (Humira, Imraldi), golimumab (Simponi), certolizumab (Cimzia), and etanercept (Enbrel).

“However, concerns exist regarding infections associated with DMARDs or anti-TNF use in AS,” researchers wrote.

To assess the risk of hospitalized infections in AS patients using either DMARDs or anti-TNF therapies, researchers took data from the Régie de l’Assurance Maladie du Québec and the Quebec provincial hospital discharge databases between Jan. 1, 2001 and Dec. 31, 2011. These databases record physician billing and hospitalization data for all residents of Quebec.

Patients were divided into three groups — those currently using DMARDs without anti-TNF, those who used anti-TNF agents alone or in combination with DMARDs (anti-TNF ± DMARDs), and non-users.

Researchers then adjusted the outcomes based on patients’ sociodemographic characteristics, comorbidity, outpatient visits and procedures, previous infection, NSAIDs and corticosteroid (a type of immunosuppressant) use.

The final cohort included 747 AS patients, 62.4% of whom were men.

During a median follow-up of 1.98 years, 57 hospitalized infections occurred, an incidence rate of 2.9/100 person years.

Among patients in the anti-TNF ± DMARDs group, the hazard ratio of infection compared to non-users was 1.00, indicating no difference in infection rate between the groups. Similar results were found in patients treated with DMARDs alone.

When looking at specific factors that contribute to higher rates of infection, researchers found that infection resulting in hospitalization in the previous year, higher number of outpatient visits and procedures before therapy initiation, and corticosteroid use were the strongest predictors.

In accordance with previous reports, being female was also associated with an increased risk of infection. Researchers hypothesized this “may be linked to the impact of urogenital infections, which are more common in females.”

Researchers said, “We found no clear evidence that the risk of hospitalized infection was linked to DMARD and/or anti-TNF drug use.”

They concluded, “Because of scarce published literature on the risk of infection in AS patients, our results have important implications for clinicians.”