Treatment practices, characteristics and outcome of immunoglobulin A nephropathy - a Swiss single center experience

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Geographic differences in disease course and treatment response are well recognized. The purpose of this analysis was to study clinical and histological characteristics, treatment practices and outcome of IgAN cases from a Swiss tertiary center.

This retrospective cohort analysis identified 158 cases of adult biopsy-proven IgAN by chart review diagnosed between 1980 and 2016. Following detailed phenotyping, standard descriptive methods and univariate analysis were applied.

The majority of patients was male and of European ancestry. At diagnosis, mean estimated glomerular filtration rate (eGFR) was 55.7 ml/min/1.73 m², mean proteinuria was 2.4 g/d and 69.9% of the patients were hypertensive. Clinical presentation varied according to age. Initial biopsies showed moderate to severe tubular atrophy and interstitial fibrosis (IFTA) in 29.1% and crescents in 36.7% of cases. Therapy included renin-angiotensin-aldosterone-inhibitors in 86.7% as well as immunosuppressive therapy in 46.8% including steroids and other immunosuppressive drugs (28.7%), mainly azathioprin. Outcome included 34.1% complete and 22.2% partial remissions, relapses in 32.0% of patients, while 43.0% of patients progressed to ESKD during follow-up (median 100.0 months). Recurrence rate after transplantation was 18.8%. Immunosuppressive therapy was more frequently used in patients with higher proteinuria level, higher hematuria grade, lower eGFR, more intense IgA and complement C3 staining and crescents. Predictors of progression were higher age, lower eGFR, higher proteinuria and blood pressure as well as crescents and higher extent of IFTA on the initial biopsy.

This retrospective cohort analysis gives insight into characteristics and outcome of patients with IgAN from a Swiss tertiary center, treatment practices as well as predictors of outcome and therapy choices. A comparatively high use of immunosuppressive treatment including non-steroid-based regimens was found along with a high rate of progression to ESKD.