SAN FRANCISCO, CA—Clinicians and patients with refractory systemic lupus erythematosus (SLE) should increase their vigilance for infection—“particularly in the early months”—following treatment initiation with rituximab, according to data from a national register presented at the 2015 ACR/ARHP Annual Meeting.
“SLE is associated with a significantly increased risk of infection,” noted Eoghan M. McCarthy, of the Central Manchester University Hospital NHS Foundation Trust, Manchester, United Kingdom. “Both disease activity and the medications required to control disease are contributory factors.”
To examine the frequency and pattern of infections related to rituximab, Dr. McCarthy and colleagues analyzed patients with SLE enrolled in the UK’s BILAG-BR, a multicenter prospective study of the safety and efficacy of biologics. They coded infection-related events using Medra software.
“Serious infections were defined as any infection resulting in treatment with IV antibiotics, hospitalization, disability, or death. For the purposes of the study, infections occurring within 9 months of rituximab were deemed to be therapy related,” he noted. Infections were categorized as being respiratory, urinary, opportunistic, skin, gastrointestinal, or other.
From May 2010 to March 2015, 208 patients treated with rituximab were followed for a median of 1 year (IQR, 0.5, 2). Of the 204 infectious episodes observed in 77 (37%) patients, 173 (85%) occurred within the 9-month window, with 25 (14%) serious infections occurring in 20 (10%) patients. A total of 50 patients had multiple infections. The overall infection rate per 100 patient years of follow-up was 57.9 and, for serious infection, 8.3.
“The highest rate of infections occurred in the first 3 months following treatment with rituximab,” Dr. McCarthy reported. Within these 3 months, 102 (59%) infections occurred, which declined over time, to 57 (33%) between 3 and 6 months and 14 (8%) between 6 and 9 months.
A similar trend was noted for serious infections, with 14 (56%) occurring within 3 months, 8 (32%) at 3–6 months, and 3 (12%) at 6–9 months.
A higher number and proportion of non-respiratory infections were observed within the first 3 months post-rituximab, 55 of 102 (54%), compared with 27 of 71 (38%) at 3–9 months (odds ratio 1.9; 95% confidence interval: 1.03–3.5, P=0.04). The most frequent opportunistic infections were Candida and Herpes zoster.
No significant differences in individual serious infections were observed across the time points; however, the proportion of non-respiratory serious infections was also higher in the first 3 months following treatment initiation with rituximab. There were no infection-related deaths.