Background/Purpose: Granulomatosis with Polyangiitis
(GPA) is associated with an increased risk of mortality. However, recent
mortality trends in GPA are largely unknown, particularly in the general
population. Our objectives were to assess mortality trends among GPA patients
between January 1, 1997 and December 31, 2012 in a general population context.

Methods:  Using an administrative health database
from the province of British-Columbia, Canada (4.7 million), we identified all
incident cases of GPA and up to 10 (6 were available) non-GPA controls matched
on sex, age, and calendar year of study entry, between 1997 and 2012. All GPA
cases required the use of glucocorticoids, immunosuppressives or methotrexate,
during the period one-month before and six-months after the date of study entry
as part of the case definition.  The GPA cohort was then divided in two cohorts
based on year of GPA diagnosis (i.e., 1997-2004 and 2005-2012) to evaluate
changes in mortality. We calculated hazard ratios (HR) for death using a Cox
proportional hazard and the rate differences using an additive hazard model,
while additionally adjusting for potential confounders (e.g., Charlson
Comorbidity Index, number of outpatient visits, hospitalization, cardiovascular
drugs, glucocorticoids and NSAIDs). 

Results:  The early cohort (1997-2004) GPA
patients had a considerable higher mortality rate than the late cohort
(2005-2012) (i.e., 150.1 cases vs. 51.1 cases per 1000 person-years), as
compared with only a moderate improvement in comparison cohorts between the two
periods (24.0 to 15.9 per 1000 person-years). The corresponding absolute
mortality rate differences were 88.2 (95% CI 55.1, 121.4) and 7.1 (95%CI -9.6,
23.8) cases per 1000 person years (p-value for interaction <0.001).

The corresponding adjusted HRs for mortality were 3.54 (95%
CI, 2.42-5.18) and 1.72 (95% CI, 1.17-2.53), respectively (p for interaction = 0.003)

Conclusion:  This population-based study shows
that survival of GPA patients has improved over the past decade, suggesting the
new treatments and improved management of the disease and its complications may
be providing substantial benefits. 

Table 1: Incidence Rates
and Hazard Ratios (HR) for Associations between GPA and Death According to
Cohort