Mortality among patients with IgA nephropathy (IgAN) is twice the expected rate, but the rate is not significantly elevated prior to the start of renal replacement therapy (RRT), Norwegian researchers reported online in the American Journal of Kidney Diseases. Moreover, the risk of end-stage renal disease (ESRD) among IgAN patients is substantially greater than the risk of death.
During a mean follow-up of 11.8 years in a cohort of 633 patients diagnosed with IgAN during 1988-2004, the number of observed deaths was 80 and the number of expected deaths was 42, resulting in an age- and gender-adjusted standardized mortality ratio (SMR) of 1.9.
The SMR, which is calculated by dividing the number of observed deaths in a study population by the number of expected deaths, for the IgAN patients varied according to their estimated glomerular filtration rate (eGFR) at the time of kidney biopsy. The researchers, led by Rune Bjørneklett, MD, PhD, of Haukeland University Hospital in Bergen, found no increase in mortality among patients with an eGFR of 60 mL/min/1.73 m2 or higher (low-risk patients), but the SMR was 1.9 for those with an eGFR of 30-60 (moderate-risk patients) and 3.6 among subjects with an eGFR below 30 (high-risk patients).
The age- and gender-adjusted SMR was not increased significantly in the pre-RRT period, but after RRT initiation, patients died at nearly five times the expected rate. Cardiovascular disease was the most common cause of death, accounting for 45% of all deaths.
The study also showed that ESRD occurred 3.2 times more frequently than pre-ESRD deaths, which is different from the findings of many other studies of chronic kidney disease (CKD), according to the researchers.
Dr. Bjørneklett’s group stated that their findings, particularly the observation that SMR is not increased among low-risk patients, indicate that pre-ESRD deaths and ESRD perhaps should be studied as separate endpoints in prognostic models of IgAN. Additionally, the researchers noted that low-risk IgAN patients have been denied access to life insurance, “probably due to their general status as CKD patients. Our results demonstrate that this is not appropriate and that patients with IgAN should be assessed on an individual basis from an insurance perspective.”