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19-08-2019 | Rheumatoid arthritis | News

Serious infection risk in TNF inhibitor-treated RA patients characterized


medwireNews: One study has demonstrated an elevated risk for serious infection among rheumatoid arthritis (RA) patients treated with tumor necrosis factor (TNF) inhibitors versus conventional DMARDs, whereas another has found no increased risk.

In the first study, Kaleb Michaud (University of Nebraska Medical Center, Omaha, USA) and co-authors drew on data from a US national databank to compare serious infection risk in 7210 patients initiating TNF inhibitor treatment, 1676 initiating a non-TNF inhibitor biologic, and 2737 initiating a conventional DMARD between 2001 and 2016.

In all, 5.9% of individuals developed serious infections – defined as infections requiring intravenous antibiotics or hospitalization or those resulting in death – over 27,552 patient–years of follow-up.

As reported in ACR Open Rheumatology, the incidence rate for serious infection was 26.9 per 1000 patient–years for those receiving TNF inhibitors and 22.4 per 1000 patient–years for the conventional DMARD group, translating into a significant 33% increased risk with receipt of TNF inhibitors after adjustment for propensity score and potentially confounding factors including age, disease duration, comorbidities, and prior medication use.

Similarly, receipt of non-TNF inhibitor biologics versus conventional DMARDs was associated with a significant 48% increased risk for serious infection, with incidence rates of 23.3 versus 22.4 per 1000 patient–years.

But there was no significant difference in incidence rates between the TNF inhibitor and non-TNF inhibitor biologics group.

Michaud et al add that a number of other factors, including older age, comorbidities, disability score, and higher corticosteroid dose, were also associated with serious infection risk in their analysis.

These results indicate that “despite the efficacy of [biologic] DMARDs […] the risk/benefit ratio should be weighed carefully when treating patients with RA, particularly older individuals with multiple comorbidities and disability,” they conclude.

In contrast to these findings, the authors of the second study found “no substantially different risk” for serious infection among methotrexate-treated RA patients from a US healthcare claims registry who initiated concomitant treatment with either a TNF inhibitor or hydroxychloroquine plus sulfasalazine between 2003 and 2014, due to an inadequate methotrexate response.

Specifically, the incidence rate for serious infection (bacterial or opportunistic infection resulting in hospitalization, or herpes zoster) was 24.6 per 1000 patient–years for the 45,208 individuals in the methotrexate–TNF inhibitor group and 20.3 per 1000 person–years for their 1387 propensity score-matched counterparts given methotrexate, hydroxychloroquine, and sulfasalazine, giving a nonsignificant hazard ratio of 1.23.

Seoyoung Kim (Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA) and fellow researchers also demonstrated no significant difference in the risk for serious bacterial infection or herpes zoster among patients in the TNF inhibitor versus triple therapy groups, at rates of 13.2 versus 9.2 per 1000 person–years and 13.5 versus 16.8 per 1000 person–years, respectively.

They note that serious opportunistic infections occurred “almost exclusively” in the TNF inhibitor group, with only a single case in the triple therapy group.

“This is the first real-world setting study that compared the infectious safety of TNF [inhibitors] plus [methotrexate] versus triple therapy,” write the researchers in Arthritis Care & Research.

However, they advise caution when interpreting the results due to “a relatively small size of the triple therapy group,” resulting in “limited statistical power” for the analysis.

By Claire Barnard

medwireNews is an independent medical news service provided by Springer Healthcare. © 2019 Springer Healthcare part of the Springer Nature group

ACR Open Rheumatol 2019; doi:10.1002/acr2.11064
Arthritis Care Res 2019; doi:10.1002/acr.24038