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Patients on dialysis are known to be at notably higher risk of contracting SARS-CoV-2 and dying from COVID-19 than the general population, and now, for the first time, a large nationwide study pinpoints further specific risk factors for infection and mortality in this population, which in fact, are broadly similar to those in the general population.
“Patients with end-stage kidney disease (ESKD) undergoing maintenance hemodialysis are particularly susceptible to SARS-CoV-2 infection, as treatment necessitates frequent visits to outpatient dialysis units,” Stephen Salerno, a PhD student at the University of Michigan, Ann Arbor, and colleagues observe in their study, published online November 17 in JAMA Network Open.
The study population of 498,169 patients represents the entire US Medicare cohort who received long-term dialysis in 2020. Among the 60,090 patients who developed COVID-19, 26% died.
“[We found that] risk factors for COVID-19 that persisted as risk factors for mortality [included] nursing home status, time on dialysis, congestive heart failure, diabetes, and comorbidity burden,” Salerno and colleagues report.
Studying the Medicare Population of 2020
Patients receiving long-term dialysis comprise 70% of the ESKD population, so understanding their SARS-CoV-2 infection and mortality risk “has sparked much interest,” Salerno and colleagues note in their article.
“Various studies have investigated the impact of COVID-19 on dialysis patients regionally or within specific dialysis organizations; however, there is a lack of literature on this patient population nationally,” they observe.
“We compared mortality trends in 2020 with historic trends in 2013 to 2019,” the authors note. The median age of patients was 66 years, slightly over 43% were women, and 12.1% received a COVID-19 diagnosis during the study period.
The 26% mortality rate in those who developed COVID-19 compared with a mortality rate of 16.9% among patients who did not “[indicates] COVID-19 was associated with higher mortality in this population,” the authors say.
Interestingly, while men were not more likely to be infected by SARS-CoV-2 than women, they had a 20% higher mortality rate than females once infected, a pattern very similar to that seen in a nondialysis population, the investigators point out.
COVID-19 infection rates were also higher among Black patients at 13.1% as well as Hispanic patients at 15.6% compared with 11.5% among non-Black patients and 11.3% among non-Hispanic patients.
Extended Nursing Home Stay Biggest Risk Factor for Infection, Death
However, the biggest difference in SARS-CoV-2 infection rates was observed between patients with a short nursing home stay of 1 to 89 days and those with an extended nursing home stay of 90 days or longer.
Compared with no nursing home stay, and adjusting for all other risk factors, prior short-term nursing home stay was associated with a 60% higher risk of contracting SARS-CoV-2, while an extended nursing home stay was associated with a 448% higher risk of contracting the infection, at a hazard ratio (HR) of 1.60 and 4.48, respectively.
The mortality rate was also 12% higher among patients with an extended nursing home stay compared to patients with either no prior time spent in a long-term care facility or those tended to in a skilled nursing facility.
“The nursing home experience during the pandemic appears to be particularly salient among the dialysis population, potentially owing to congregate living, the inability to socially distance, and higher frailty and comorbidity burden among nursing home residents,” the researchers observe.
Older age, higher body mass index, heart failure, diabetes, cerebrovascular disease, inability to ambulate, and higher comorbidity burden were also all associated with a higher risk of becoming infected with SARS-CoV-2, the authors note.
In contrast, living in an urban area was associated with a 10% lower risk of dying from COVID-19.
Conversely, home dialysis was associated with a 23% lower risk of becoming infected with the virus, but on the flipside, was also associated with an 18% higher risk of death once patients became infected. The researchers note that this contrasts with results from another recent study that found a lower COVID-19 mortality rate among patients receiving dialysis at home (J Am Soc Nephrol. 2021;32:1569-1573).
The investigators also point out that annual trends in all-cause mortality between 2013 and 2019 among patients on dialysis showed a well-known seasonal pattern of mortality, with peaks in late January and early February.
“Beginning in 2020, deviations from this trend were commensurate with known waves of the COVID-19 pandemic,” they report.
“To our knowledge, this cohort study is the first national study using Centers for Medicaid and Medicare Services (CMS) claims data to evaluate COVID-19 outcomes in the Medicare dialysis population using all available 2020 data through December 2020,” investigators observe.
“These results improve our understanding of COVID-19 and [its] complications in this high-risk population and could inform policy decisions to mitigate the added burden of COVID-19 and death,” they conclude.
The research was funded by the CMS. Salerno has reported no relevant financial relationships.
JAMA Netw Open. Published online November 17, 2021.
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