Risk and trends of severe infection in patients with antineutrophil cytoplasmic antibody-associated vasculitides: a two-part population-based trajectory analysis.

objectivesTo evaluate the risk of severe infection and examine the secular change in infection counts among patients with newly diagnosed antineutrophil cytoplasmic antibody-associated vasculitides (AAV).

methodsWe conducted an age- and sex-matched cohort study of all patients with incident AAV, using administrative health data from British Columbia (1997-2022). We used multivariate Cox proportional hazard models to compare the time to the first severe infection after AAV onset. To examine long-term risk patterns of repeated severe infections, we used a zero-inflated Poisson mixed model.

resultsAmong 1626 AAV patients and 16,260 matched controls, AAV patients had a higher adjusted hazard ratio for first severe infection (HR = 2.83; 95% CI = 2.41-3.33). The trajectory analysis revealed that AAV patients at the time of disease onset had higher odds of being at risk of severe infection (OR = 9.87). The odds of being at risk of severe infection remained unchanged for AAV patients over time. The rate of severe infection counts for the AAV patients at risk was greater (RR = 2.86) at the disease onset, reduced annually by 23% (RR = 0.77) for the first 2 years, but increased annually by 7% thereafter (RR = 1.07).

conclusionsAAV was associated with an increased risk of severe infections, affecting one in three patients. While this increased risk decreased over time, AAV patients who were still at risk exhibited an increasing rate of recurrent infections beyond 2 years post-diagnosis. This highlights the urgent need for targeted strategies in these vulnerable AAV patients. Key Points • No incident cohort study with a large sample size has examined the association between AAV and the risk of severe infection after accounting for potential confounders. • One in three patients with newly diagnosed AAV developed severe infection (2.8-fold when compared to non-AAV). AAV patients had the highest risk of severe infection during the first 30 days of diagnosis, which dropped at different rates before and after the second year. • Among those at risk for severe infections, the rate of repeated severe infections decreased over time within the first 2 years of AAV diagnosis and increased over time afterward. • Our findings highlight that severe infection is still common in AAV patients. Targeted strategies to reduce the long-term risk among infection-susceptible AAV patients are urgently needed.