Mortality in IgA Nephropathy: A Nationwide Population-Based Cohort Study.

Background: The clinical course of IgA nephropathy (IgAN) varies from asymptomatic nonprogressive to aggressive disease, with up to one in four patients manifesting ESRD within 20 years of diagnosis. Although some studies have suggested that mortality appears to be increased in IgAN, such studies lacked matched controls and did not report absolute risk.

Methods: We conducted a population-based cohort study in Sweden, involving patients with biopsy-verified IgAN diagnosed in 1974-2011; main outcome measures were death and ESRD. Using data from three national registers, we linked 3622 patients with IgAN with 18,041 matched controls; we also conducted a sibling analysis using 2773 patients with IgAN with 6210 siblings and a spousal analysis that included 2234 pairs.

Results: During a median follow-up of 13.6 years, 577 (1.1%) patients with IgAN died (10.67 per 1000 person-years) compared with 2066 deaths (0.7%) in the reference population during a median follow-up of 14.1 years (7.45 per 1000 person-years). This corresponded to a 1.53-fold increased risk and an absolute excess mortality of 3.23 per 1000 person-years (equaling one extra death per 310 person-years) and a 6-year reduction in median life expectancy. Similar increases in risk were seen in comparisons with siblings and spouses. IgAN was associated with one extra case of ESRD per 54 person-years. Mortality preceding ESRD was not significantly increased compared with controls, spouses, or siblings. Overall mortality did not differ significantly between patients with IgAN-associated ESRD and patients with ESRD from other causes.

Conclusions: Patients with IgAN have an increased mortality compared with matched controls, with one extra death per 310 person-years and a 6-year reduction in life expectancy.