Temporal Trends in Incidence and Outcomes of End-Stage Renal Disease due to Granulomatosis with Polyangiitis in the US from 1995-2014

Background/Purpose:

Granulomatosis with polyangiitis (GPA) often affects the kidneys, frequently leading to end-stage renal disease (ESRD). The national trends in the frequency and outcomes of ESRD due to GPA are largely unknown, although these data would provide important benchmarks in assessing GPA disease burden and care.  Our objective was to examine temporal trends in the incidence and outcomes of ESRD due to GPA.

Methods:

We identified ESRD due to GPA in the US Renal Data System (USRDS) between 1995 and 2014, using nephrologists’ ICD-9 coding (446.4) for the ESRD etiology. The cohort was divided into four five-year subcohorts based on year of ESRD onset. Overall and sociodemographic group trends in incidence rates (IRs) were assessed. Changes in rates for mortality, waitlisting, and transplantation were assessed using Cox-proportional hazards models. We conducted analyses taking into account the competing risk of death in analyses for the outcomes of waitlisting and transplantation 

Results:

Between 1995 and 2014, there were 5,929 incident cases. The annual incidence rate increased over the study period (P-for-trend <0.0001).  The incidence rate of death (per 1,000 patient-years) declined from 19.0 (17.2-21.1) to 15.3 (14.0-16.7, P<0.0001) with a corresponding adjusted HR of 0.77 (95% CI, 0.67-0.89). The log-rank test also showed significant improvement in survival during the study period (P=0.03) (Figure 1). Adjusted HRs for death were 1.0, 0.90, 0.82, and 0.77 for the 1995-1999, 2000-2004, 2005-2009, and 2010-2014 sub-cohorts, respectively (P-for-trend = 0.005). Accounting for competing risk, there was a 70% increase in the risk of being waitlisted for transplant (adjusted HR for 2010-2014, vs 1995-1999 = 1.7, 95% CI, 1.38-2.11), whereas the risk for transplantation decreased by 30% (corresponding adjusted HR = 0.70, 95% CI, 0.53-0.93). 

Conclusion:

The burden of ESRD due to GPA has increased in the US over the past two decades, which is likely related to overall improvements in GPA survival.  During the same period, survival of patients with GPA ESRD has improved, although the likelihood for being waitlisted for a transplant is rising with access to renal transplantation becoming more limited. With 5,929 GPA ESRD patients included, this is the largest AAV study to date in the literature.   

Figure 1: Kaplan-Meier Curve of Overall Survival in ESRD due to GPA (1995-2014)