Kidney failure up to 29 times more common in CF patients: Study
Researchers also identified, diabetes, lung transplant as most frequent causes
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Kidney failure, when the kidneys no longer work on their own, is up to 29 times more common in people with cystic fibrosis (CF) than in the general U.S. population.
That’s according to a recent study, which also identified diabetes and complications associated with lung transplant as the most frequent causes of kidney failure in CF patients.
“We recommend routine monitoring of kidney function in people with cystic fibrosis, and consideration of interventions which reduce the risk of kidney failure,” researchers wrote in the study “Kidney Failure in Persons With Cystic Fibrosis,” which was published in Kidney Medicine.
CF caused by mutations in key gene
CF is caused by mutations in the CFTR gene, which encodes a protein with the same name that normally helps cells regulate the flow of salt and water. These mutations result in the loss or dysfunction of the CFTR protein, leading to the production of thick, sticky mucus in several organs that ultimately drives the disease’s symptoms.
Several studies have reported that CF patients may have kidney problems, including chronic kidney disease, which may progress to kidney failure requiring dialysis and kidney transplant.
To assess the frequency and outcomes of kidney failure in CF, researchers at Dartmouth College used data from the U.S. Renal Data System, a nearly complete record of all U.S. individuals with kidney failure.
Among people with kidney failure identified between 2014 and 2018, 379 had CF, and more than 954,000 did not have the disease. Kidney failure was estimated to affect 6.8 to 8.8 per 1,000 individuals with CF, and 0.3 per 1,000 individuals in the general U.S. population younger than 40. This means that the estimated prevalence was 22.6 to 29.3 times higher among CF patients than in the general U.S. population of similar age.
People with CF were significantly younger than those without CF when kidney failure started (41.9 vs. 58.5 years), were more commonly women (51.2% vs. 43.1%), and had a lower mean body mass index (BMI), a measure of body fat based on height and weight (23.2 kg per square meter vs. 29.6 kg per square meter). They were also more likely to have specialized kidney care before kidney failure.
Diabetes primary cause of kidney failure in people without CF
After adjusting for age, sex, BMI, race, and prior kidney care, CF patients were 36% less likely to receive peritoneal dialysis rather than hemodialysis as the first treatment modality. In hemodialysis, blood is filtered using an external machine, while in peritoneal dialysis, the inner lining of the abdomen is used to filter blood.
Among CF patients, the main cause of kidney failure was diabetes (24.3%). Other causes included complications related to organ transplant (20.6%), most commonly the lung (16.9%), hypertension, or high blood pressure (9.8%), glomerulonephritis (9.8%), and toxins or medications (8.2%). Glomerulonephritis refers to inflammation of the tiny filters in the kidneys.
In people without CF, diabetes was the primary cause of kidney failure even more frequently (42.3%), followed by hypertension (26.3%). Complications associated with organ transplant were rarely the cause of kidney failure among these patients.
Overall, the median survival with kidney failure was not significantly different between CF patients and people without the disease (12.6 vs. 11.8 years).
CF patients with kidney failure due to diabetes had a significantly shorter survival than those with kidney failure due to other causes (5.6 vs. 13.4 years) and those without CF with kidney failure caused by diabetes (12.6 years).
“The markedly increased prevalence of kidney failure in [people with CF], together with the observation that … survival with kidney failure was comparable to those without CF, underlines the importance of diagnosis and active management … especially in consideration of lung, liver or pancreas transplantation,” the researchers wrote.
