SCD Patients at Higher Risk of Death From Kidney Disease, Study Finds

Despite better outcomes in US population, survival remains poor in SCD

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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The risk of death from end-stage kidney disease (ESKD) has generally declined in the U.S. over the last 20 years — but not as much for people with sickle cell disease (SCD).

Patients with the genetic disorder still have a higher risk of mortality than those without SCD, a new study found. Sickle cell patients also are diagnosed with ESKD younger than the general population, and are less likely to receive a kidney transplant for the condition.

Indeed, the findings show “this disparity in survival was magnified,” with sickle cell patients with kidney disease having “a 2.7 times higher hazard of mortality.”

“This study confirms that patients with SCD who develop ESKD continue to experience disparities in [kidney] outcomes,” the researchers wrote. “Ongoing research should identify risk factors for ESKD progression, ensure implementation of monitoring for kidney disease, and determine therapies that prevent the development of ESKD.”

The study, “Patients with sickle cell disease who develop end-stage kidney disease continue to experience poor survival — A 19-year United States Renal Data System study,” was published as a letter to the editor in the British Journal of Haematology.

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Higher risk of kidney disease in SCD

People with SCD are at an elevated risk of developing chronic kidney disease and experience more rapid declines in kidney function compared with the general population.

Some patients will eventually develop kidney failure, or ESKD, in which continuous dialysis or a kidney transplant is needed for patients to survive. ESKD may in part contribute to the early mortality observed in the SCD population.

Previous studies have suggested that sickle cell patients with EKSD may not be receiving prompt or adequate treatment for their kidney condition.

“Despite improvement in care over the last two decades, the prognosis of SCD-ESKD remains uncertain,” the researchers wrote.

With this in mind, a team in the U.S. analyzed the outcomes of sickle cell patients with end-stage kidney disease from 1998 to 2017, based on data from the United States Renal Data System registry.

During that time, 2,194,079 people developed ESKD, 2,018 (0.09%) of whom had an SCD diagnosis.

SCD patients were diagnosed with kidney failure at a significantly younger age, by about 10 years, than people without SCD. Specifically, the median age was 44 for Black patients with SCD versus 59 for Black patients without the blood disorder. For non-Black individuals, the median age at diagnosis was 49 for those with sickle cell disease versus 66 for patients without SCD.

Male SCD patients were significantly younger at the time of ESKD diagnosis than were female patients.

Notably, SCD patients were 76% less likely to receive a preventive kidney transplant — before needing to start dialysis — than to initiate dialysis. They were, however, more likely to have received ongoing kidney care before reaching ESKD than not having any care.

Mortality rates generally declined over the 19-year study period in both groups, lowering by 35% for non-SCD patients and by 30% for SCD patients.

Despite the increase in pre-ESKD kidney care and a drop in mortality over time among SCD patients with ESKD, their risk of death remained higher relative to people without the disease.

After adjusting for potentially influential factors such as age, sex, ethnicity, Black race, initial treatment modality, and co-existing health conditions, SCD patients had a 2.7 times higher risk of death than non-SCD individuals after a first ESKD event.

In addition, people with SCD and ESKD were 51% less likely to receive a kidney transplant than the non-SCD group, after adjusting for age, sex, ethnicity, and Black race. Notably, a significant reduction in the rate of kidney transplants was observed over time for non-SCD patients, but not for the SCD group.

“It remains alarming that patients with SCD-ESKD were less likely to receive a kidney transplant as compared to non-SCD-ESKD patients,” the researchers wrote.

Overall, these findings highlight that “patients with SCD continue to develop ESKD earlier in life, have a higher risk of death, and lower transplant rate than non-SCD-ESKD patients,” the team wrote.

The study was limited by some missing information from the database. This included stage of kidney disease at referral or effects of approved SCD therapies and kidney-protective medications on the progression to ESKD.

“Large prospective … studies are needed to determine the impact of therapies on progression of kidney disease,” the researchers concluded.