The incidence of severe infections is increased under biologic therapies and the skin is the second localization.
To appraise the factors associated with severe skin infections (SSI) in patients under biologic therapies for inflammatory rheumatic diseases (IRD).
We performed a case-control (ratio 1:3) study nested in a prospective cohort of patients with IRD. SSI was defined as requiring hospitalization or intravenous anti-infectious therapy. We defined two imbedded periods: period A was the time window between the first biologic therapy and the SSI; period B was the last 3 or 12 months (for tumor necrosis factor blockers or rituximab, respectively) before the SSI.
Among 4,361 patients with IRD, 29 had a SSI under biologic therapy. In multivariate analyses, SSI were significantly associated with smoking, baseline C-reactive protein and gammaglobulinemia, non-steroidal anti-inflammatory drugs before biologic therapy, cumulative dose of steroids, concomitant steroids during period A, number of different biologic therapies during period A, treatment with infliximab during period A, period B or as first biologic therapy and treatment at high dose during period B.
In patients under biologic therapies for IRD, the risk of SSI is associated with several factors including tobacco, treatment with infliximab or high dose range.