Improved survival in granulomatosis with polyangiitis: A general population-based study

Background: Granulomatosis with polyangiitis (GPA) is associated with an increased risk of mortality; however, recent mortality trends in GPA are unknown. We evaluated this issue in a general population context.

Methods: Using data collected between 1992 and 2013 by The Health Improvement Network in the United Kingdom, we identified individuals diagnosed as incident cases of GPA and up to 10 non-GPA controls matched on sex, age, year of birth, and year of GPA diagnosis. The cohort was divided into two based on the year of diagnosis (i.e., 1992-2002 and 2003-2013) to evaluate changes in mortality. We calculated hazard ratios for death using a Cox-proportional hazards model and the rate differences using an additive hazard model, while adjusting for potential confounders.

Results: We identified 465 cases of GPA (mean age: 60 years, 52% male). The early cohort (1992-2002) GPA patients had considerably higher mortality rates than the late cohort (2003-2013) (i.e., 72.0 vs. 35.7 cases per 1000 person-years), as compared with a moderate improvement in the comparison cohorts between the two periods (19.8 vs. 17.0 cases per 1000 person-years). The corresponding absolute mortality rate difference was 52.2 (95% CI: 25.1-79.2) cases and 18.7 (95% CI: 8.3-29.1) cases per 1000 person-years (p for interaction = 0.025). The resulting HRs for mortality were 4.34 (95% CI: 2.72-6.92) and 2.41 (95% CI: 1.74-3.34), respectively (p for interaction = 0.043).

Conclusion: This population-based study suggests that survival of GPA patients has improved considerably over the past 2 decades, affirming the benefits of recent trends in the management of GPA and its complications.