Study finds less than 10% of patients with ESKD have SARS-CoV-2 antibodies
Although less than 10% of patients on dialysis who were tested in a large study group last July had the antibodies for SARS-CoV-2, Black and Hispanic patients had a higher percentage of seroprevalence for the virus than white patients.
Shuchi Anand, MD, and colleagues from Stanford University School of Medicine reviewed data from 28,503 randomly selected adult patients who were treated at approximately 1,300 dialysis facilities across the United States. Patients all received their testing at labs owned by Ascend Clinical Laboratories, which also funded the study.
The authors wrote that patients on dialysis were chosen for the study because “they share the socioeconomic characteristics of underserved communities, and undergo routine monthly laboratory testing, facilitating a practical, unbiased, and repeatable assessment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence.”
Anand told Healio Nephrology that using this patient population for the study also helped researchers avoid the potential for selection bias.
“Seroprevalence studies represent a strong approach to track the spread of SARS-CoV-2 in communities,” she said. “However, community-based seroprevalence studies face challenges due to high likelihood of selection bias (eg, underrepresentation of racial/ethnic minorities, people with underlying health conditions and people with language barriers), compounded by the difficulty in outreach in light of the COVID-19 pandemic. Furthermore, they do not allow for longitudinal follow-up.”
Data were extracted regarding age, sex, race and ethnicity, as well as residence and facility ZIP codes. Electronic health records also linked patient-level residence data with cumulative and daily cases and deaths per 100,000 population and with nasal swab test positivity rates.
Researchers noted the sampled population had similar age, sex and race and ethnicity distribution to the U.S. dialysis population, but had a higher proportion of older people, men and people living in neighborhoods of predominantly Black residents and Hispanic residents compared to the U.S. adult population.
Results showed seroprevalence of SARS-CoV-2 was present in 8% of the total sample, 8.3% when standardized to the U.S. dialysis population and 9.3% when standardized to the U.S. adult population.
Anand said the researchers expected to find a seroprevalence of approximately 5% based on prior reports from the CDC Six Cities Study, a New York grocery store study and a Los Angeles county-based California study.
Further findings indicated residents living in predominantly Black and Hispanic neighborhoods experienced higher odds of seropositivity compared with residents of predominantly white neighborhoods.
“ ... [W]e find increased likelihood of SARS-CoV-2 seropositivity in residents of predominantly Black and Hispanic neighborhoods (two to three times higher), poorer areas (two times higher), and the most densely populated areas (ten times higher),” the authors wrote.
In addition, researchers observed residents of neighborhoods in the highest population density quintile experienced increased odds of seropositivity (OR = 10.3 [8.7 to 12.2]) compared with residents in the lowest density quintile.
Anand and colleagues acknowledged that comparing the study results, based on the end-stage kidney disease population, might not be transferrable to results in the general population, writing that “[u]ncertainty exists as to whether seroprevalence estimates in the dialysis population can be extrapolated to the U.S. population more broadly.”
Of their findings, the researchers concluded: “During the first wave of the COVID-19 pandemic, fewer than 10% of the U.S. adult population formed antibodies against SARS-CoV-2, and fewer than 10% of those with antibodies were diagnosed. Public health efforts to limit SARS-CoV-2 spread need to especially target racial and ethnic minority and densely populated communities.”