Antimicrobial use rises following TNFi initiation in patients with PsA

A recent study has noted a temporary increase in antimicrobial use following initiation of tumour necrosis factor inhibitor (TNFi) treatment, with no significant risk in serious infections, among patients with psoriatic arthritis (PsA).

In this study, the authors extracted data on patients with PsA (n=399) initiating TNFi from 2005 to 2018 from the ICEBIO registry and matched them to five randomly selected comparators (n=1986) from the general population by age, sex, and calendar time.

They also extracted filled prescriptions for antimicrobials, glucocorticoids, and methotrexate 2 years before and after TNFi initiation from the Icelandic Prescription Medicines Register. In addition, all infection-related hospitalizations, a proxy for serious infections, were extracted from the Icelandic Hospital Discharge Register.

Patients received more prescriptions of antimicrobials prior to TNFi treatment, with a mean of 1.26 vs 0.60 prescriptions per year (p<0.001). The mean number of prescriptions rose to 1.64 (p<0.001) in the 12 months following TNFi initiation but returned to baseline thereafter.

The incidence of serious infections did not significantly increase. Patients with PsA had an adjusted hazard ratio of 1.43 (95 percent confidence interval, 1.18‒1.72; p<0.001) for receiving an antimicrobial prescription after TNFi initiation compared with prior TNFi treatment. This risk increased in the first year after treatment initiation but not in the second year, which indicated a transient effect.

“These results support the safety of TNFi in PsA management, and the risk of serious infections should not weigh heavily in treatment decisions,” the authors said.