Skin infections linked to Rheumatoid Arthritis treatment

Photo courtesy of Jeannette Maw

Rheumatoid arthritis (RA) can be a crippling condition on its own, but UK researchers of mainly the University of Manchester recently linked treatment drugs to increasing patient risk for also developing shingles. The drugs linked were anti-tumor necrosis factor (Anti-TNF) drugs. Specifically, they were Enbrel (etanercept), Remicade (infliximab), and Humira (adalimumab).

Rheumatoid arthritis is a condition causing increased inflammation, pain, and stiffness of normally flexible joints such as those in the wrists, fingers and ankles. The inflammation is due to an overreaction of the body’s immune system, but the cause of this overreaction is unknown. Anti-TNF drugs work to treat by turning off TNF, a group of cytokines that trigger inflammatory response naturally, and turning down inflammation (and immune response in general) to release joint pressure and relieve pain.

Shingles is a painful skin rash caused by the chickenpox virus usually popping up in those with compromised immune systems.

In this observational study, 11,881 patients who received anti-TNF treatment and 3,673 patients who received disease modifying anti-rheumatic drugs (DMARDs) all whom had RA were followed from 2001-2013 and given (as well as their Tx team) semiannual questionnaires regarding inpatient information. Only 3 consecutive years of followup data was used due to information lacking in certain years. The study was designed to find difference in incidence of severe skin and soft tissue infection (SSSI) and shingles between the anti-TNF taking patient cohort and DMARD cohort.

The incidence rate of SSSI was 1.6/100 patient-years in anti-TNF group and 0.7/100 patient-years in DMARD group. This meant a more than doubled chance of developing an SSSI while taking anti-TNF than DMARD [(HR = 2.2, 95% CI 1.5 to 3.0) & (Adjusted HR = 1.3, 95% CI 0.8 to 2.2)].

With 320 reported cases of shingles in this study, incidences were shown as 1.6/100 patient-years in anti-TNF group and 0.8/100 patient-years in DMARD group. Again, this showed a doubled risk of developing shingles in the anti-TNF group.

Individually, the adalimumab drug takers had the lowest incidence of accompanying skin diseases while those taking infliximab were in the group having higher rates of disease.

Anti-TNF drugs significantly increased the risk of developing SSSIs and shingles. Taken together, it seems those with rheumatoid arthritis (and physicians treating them) must be wary of skin infections when choosing treatment.

Reference:
James B. Galloway, Louise K. Mercer, Alison Moseley, William G. Dixon, Andrew P. Ustianowski, Matthew Helbert, Kath D. Watson, Mark Lunt, Kimme L. Hyrich, Deborah P.M. Symmons. Risk of skin and soft tissue infections (including shingles) in patients exposed to anti-tumour necrosis factor therapy: results from the British Society for Rheumatology Biologics Register. Annuals of the Rheumatic Diseases, 2013.
http://dx.doi.org/10.1136/annrheumdis-2011-201108

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