Large Kaiser Permanente study points to importance of identifying patients early and preventing complications
By Sue Rochman
Adults diagnosed with the kidney condition known as primary nephrotic syndrome are at high risk of developing end-stage kidney disease and cardiovascular disease, new research from Kaiser Permanente shows.
The findings, reported June 18 in the Journal of the American Society of Nephrology, are from The Kaiser Permanente Nephrotic Syndrome Study, one of the largest studies to look at health outcomes in people with this uncommon but serious kidney condition.
“Primary nephrotic syndrome is not a very common disorder, and we wanted to do this study because there may be a general underappreciation of the wide range of complications that people with this syndrome experience,” said the study’s lead author Alan S. Go, MD, a senior research scientist at the Kaiser Permanente Division of Research. “The higher risk of developing end-stage kidney disease would be more expected. But more importantly we were able to show the increased risk for different kinds of cardiovascular events, and that’s less appreciated in the medical community.”
Primary nephrotic syndrome is a condition that occurs when a person develops a disease that damages the small blood vessels near the part of the kidneys that filters waste from the blood. These diseases cause a protein called albumin to seep into the urine instead of being returned to the bloodstream. It can be diagnosed through a urine test, a blood test, or a kidney biopsy.
The new study compared the health outcomes of 907 adults with primary nephrotic syndrome treated in Kaiser Permanente Northern California (KPNC) between 1996 and 2012 with those of 89,593 healthy KPNC members. In their comparative analyses, the researchers accounted for factors that could influence the findings, such as the study participants’ age, gender, and socioeconomic status as well as their other health conditions.
The study found that over a median of 4.5 years of follow-up, the patients with primary nephrotic syndrome were 20 times more likely to develop end-stage kidney disease and 2 to 3 times more likely to have a heart attack, stroke, heart failure, or to develop a blood clot in a deep vein. In addition, the patients with primary nephrotic syndrome had a 34% higher rate of death.
The study also compared outcomes for patients with the 3 diseases most likely to cause primary nephrotic syndrome: minimal change disease, focal segmental glomerulosclerosis (FSGS), and membranous nephropathy (MN). These analyses showed the risk for end-stage kidney disease was significantly higher in patients with FSGS and MN than in patients with minimal stage disease. People with end-stage kidney disease must have routine dialysis or a kidney transplant to extend their lives.
“This research puts into perspective how dangerous primary kidney disease is in terms of progression and the risk of developing end-stage kidney disease,” said nephrologist Leonid Pravoverov, MD, who heads the Kaiser Permanente National Renal Care Services and was not involved with this study. “We often talk about diabetes, obesity, and high blood pressure, and how they put people at high risk for kidney disease and cardiovascular disease. But this study shows that while primary nephrotic syndrome is much rarer, the risk of adverse outcomes associated with this disease are incredibly high.”
Go said the study findings highlight the need for patients with primary nephrotic syndrome to be identified as early as possible. “Early identification makes it possible to evaluate patients for preventive therapies that can reduce their risk for both cardiovascular disease and end-stage kidney disease,” said Go. “It also allows these adults to start implementing the lifestyle changes, like stopping smoking, getting more exercise, and eating a healthy diet that are also necessary to reduce their risk for these diseases.”
Funding for this research was provided by the Brin Wojcicki Foundation.
Co-authors include Thida C. Tan, MPH, Dongjie Fan, MSPH, Farzien Khoshniat-Rad, BS, Jingrong Yang, MA, and Rishi V. Parikh, MPH, of the Division of Research; Juan D. Ordonez, MD, MPH, David Law, MD, Leonid Yankulin, MD, Sijie Zhang, MD, PhD, and Kenneth K. Chen, MD, of The Permanente Medical Group; Glenn M. Chertow, MD, MPH, of Stanford University; and Janet M. Wojcicki, PhD, MPH, of the University of California, San Francisco.
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About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 600-plus staff is working on more than 450 epidemiological and health services research projects. For more information, visit divisionofresearch.kaiserpermanente.org or follow us @KPDOR.