Severe problem- infection in ANCA vasculitis

Welcome to the October #chatJRheum discussion forum.

You may already be aware that patients with ANCA-associated vasculitis (AAV) have higher infection rates. This is believed to be a result of organ damage, inflammation and immunosuppression therapy. This month’s featured study further characterizes rates of serious infections among patients with AAV, and describes predictors and outcomes.

A total of 186 incident cases of AAV diagnosed from 1998–2010 were studied from a southern Sweden registry. For each case, 4 reference persons matched for age, sex, and area of residence were randomly chosen from the 701,000 reference population of the area.

Important results  from the study worth noting include the following:

1. Almost half of AAV patients experienced a severe infection requiring hospitalization (46%), compared to 16% of the reference subjects (a rate that was 4.5 times higher).

• This number stands out to me as a high number. Is this what you might have expected based on other literature and based on your clinical experience?

2. The rate of infection was not significantly different during the first 6 months after diagnosis (38.4%) compared to 7–24 months after the diagnosis (30.2%) and 24 months after diagnosis (31.4%).

• This implies that serious infection was just as likely in the maintenance phase, once cyclophosphamide is completed and when patients are typically treated with azathioprine, low doses of glucocorticoids, or potentially even on no immunosuppression. This had me rethink the impact of treatment on infection and highlights the ongoing need for monitoring of infection in this high-risk population.

3. There was no increase in relative infection rate between the early cohort who were more likely to have been treated with oral cyclophosphamide (1998-2003) compared to the recent cohort (2004- 2009) who were more likely to have been treated with pulse IV cyclophosphamide.

• The authors note this was not an anticipated finding, and differs from other studies of cyclophosphamide, like the CYCLOPS trial. This would be a good time to revisit the CYCLOPS trial, a pivotal study in guiding current treatment of AAV. Click here.

4. Risk factors for severe infections included increased age at diagnosis and higher serum creatinine at diagnosis.

• Can you think about reasons why that might be the case? The authors do give some insightful explanations for these observed differences.

I hope to hear your thoughts on this topic, and of course welcome your comments or questions to add to this discussion.

- Sarah Troster, forum moderator