Relation between duration of the prodromal phase and renal damage in ANCA-associated vasculitis

BACKGROUND: In ANCA-associated vasculitis the acute phase of the disease is often preceded by prodromal symptoms. The aim of the present study was to analyze the relation between the duration of the prodromal phase and renal damage. METHODS: Patients with ANCA-associated vasculitis and renal involvement from a retrospective single-center cohort were divided into two equal groups based on the duration of the prodromal phase. The prodromal phase was defined as the time between first vasculitis related symptoms and the date of diagnosis. Clinical characteristics at diagnosis and renal items on the vasculitis damage index at 6 months were compared between the two groups. In addition, the relation between a long prodromal phase and 3-year end-stage renal disease and mortality as a composite outcome was studied. RESULTS: A total of 72 patients were included (age 64 ± 12 years; 74% male; 96% Caucasian). At diagnosis, in patients with a prodromal phase ≤22 weeks versus >22 weeks estimated glomerular filtration rate and proteinuria did not differ significantly (35 (interquartile range 50) versus 30 (50) ml/min p = 0.84; 75% versus 87%, p = 0.21 respectively). Furthermore, Birmingham Vasculitis Activity Scores were comparable (7 (3), p = 0.71). At 6 months, a long prodromal phase was associated with proteinuria (odds ratio 5.38, 95% confidence interval (CI) 1.47–19.62), but not with an estimated glomerular filtration rate ≤ 50 ml/min (odds ratio 0.89, 95% CI 0.33–2.37) in multivariable analyses. In addition, a long prodromal phase was associated with end-stage renal disease/mortality (hazard ratio 5.22, 95% CI 1.13–24.20). CONCLUSIONS: A long prodromal phase was associated with proteinuria and 3-year end-stage renal disease/mortality, but not with a reduced renal function at 6 months. These results underline the importance of an early diagnosis in ANCA-associated vasculitis patients in order to improve renal outcomes.