Hispanic dialysis patients have significantly higher rates of Staphylococcus aureus bloodstream infections compared with white dialysis patients, according to a CDC study.
In 2020, rates of S. aureus bloodstream infections in hemodialysis patients were 40% higher among Hispanic patients versus non-Hispanic whites (adjusted rate ratio [aRR] 1.4, 95% CI 1.2-1.7, P<0.001), reported Shannon Novosad, MD, of the CDC National Center for Emerging and Zoonotic Infectious Diseases in Atlanta, and colleagues in Morbidity and Mortality Weekly Report.
"A comprehensive approach to preventive care that recognizes racial, ethnic, and socioeconomic disparities is needed," the group wrote. "Healthcare providers and public health professionals should prioritize prevention and optimized treatment of ESKD [end-stage kidney disease], identify and address barriers to lower-risk vascular access placement, and implement established best practices to prevent bloodstream infections."
The U.S. has more than 800,000 patients with ESKD, and 70% of those are treated with dialysis, Novosad and co-authors noted. Of those on dialysis, 89% receive hemodialysis and 11% receive peritoneal dialysis.
Their findings also showed that patients on dialysis from 2017-2020 were 100 times more likely to experience S. aureus infections compared with adults not on hemodialysis (4,248 vs 42 per 100,000 person-years).
Prevalence of ESKD is fourfold higher among Black persons and more than twofold higher among Hispanic than among white persons, "disparities which are thought to be attributable at least in part to underlying conditions such as hypertension and diabetes," the authors wrote. "Furthermore, disparities in pre-ESKD nephrology care and receipt of ESKD therapies exist for these same groups, as well as those with lower income and insurance coverage. Black persons constitute 33% of all U.S. patients receiving dialysis, but only 12% of the U.S. population."
Among hemodialysis patients, bloodstream infections -- particularly S. aureus -- are a leading cause of morbidity and mortality; 40% of S. aureus infections are of the methicillin-resistant variety (MRSA). Type of hemodialysis plays a role in infection risk, in that "risk is highest for central venous catheters (CVCs), lower for grafts, and lowest for fistulas," they said. However, Novosad's group added that "although elevated rates have been reported for both invasive MRSA infections among Black dialysis patients and hospitalizations for dialysis-related infections among adult Black patients and older Hispanic patients (aged >60 years), the association among hemodialysis-related infections, race and ethnicity, and social determinants of health is largely undescribed."
To further explore this area, they looked at infection reports from 7,097 dialysis centers in 2020. A statistical model was used to assess potential associations between the main outcome of facility S. aureus bloodstream infection incidence with patient vascular access type and selected dialysis facility characteristics, including those related to infection control practices and Social Vulnerability Index (SVI) data.
During the year studied, 14,822 bloodstream infections were reported by 4,840 facilities. Of those infections, 34.2% (n=5,070) were found to be S. aureus. "Among reported S. aureus bloodstream infections, 2,602 (51.3%) were identified as methicillin-sensitive and 1,923 (37.9%) as MRSA; 545 (10.7%) had no susceptibility test results reported," the investigators noted.
They also reported that S. aureus bloodstream infection risk was most strongly linked with patient vascular access type. Compared with fistula access, CVC had about six times higher risk (adjusted RR 6.2, 95% CI 5.7-6.7) while graft or other had around two times higher risk (aRR 2.2, 95% CI 2.0-2.4).
Facility characteristics significantly tied to higher S. aureus infection incidence included any hospital affiliation, not being part of a chain of dialysis centers, not having a written antibiotic use policy, and location in an area with a higher proportion of people ages ≥65.
Black patients had higher crude rates of infection, but the difference was not significantly different in the adjusted analysis (aRR 1.1, 95% CI 0.9-1.2, P=0.40).
Other variables associated with higher infection rates included male sex, older age (≥65), and specific surveillance sites. "However, CVC access had the strongest effect of all factors assessed," the authors noted, with the highest rates occurring among Black patients (ages 18-49). They added that "65% of bloodstream infections in this age, race, and ethnicity subgroup involved CVCs, which represented the highest prevalence of CVC use among the age, race, and ethnicity groups with bloodstream infections."
Despite those results, "potentially important associations between race and ethnicity and vascular access type used should also be considered," the authors said. "For example, recent national data suggest that initiation of hemodialysis with a CVC does not vary substantially by race, ethnicity, or SES [socioeconomic status], although other studies have shown associations among Black race, Hispanic ethnicity, poverty, insurance status, and shorter duration of pre-ESKD care with lower initiation with fistula."
SES may have figured into the current results, according to the researchers. "U.S. Census Bureau tracts with lower SES factors accounted for disproportionately higher proportions of hemodialysis-associated S. aureus bloodstream infections," they said. "For example, 42.1% of S. aureus bloodstream infections among patients on hemodialysis occurred in tracts in the highest quartile of population proportion living below the poverty level, versus 10.4% in tracts in the lowest poverty quartile."
Why was CVC access associated with a higher infection risk? Because one end of the CVC tube remains outside the body, "[it is] exposed to germs which can enter the tube and move into the bloodstream," Novosad said during a call with reporters Monday. "Removing barriers to lower-risk vascular access types for dialysis treatments is a critical step for preventing infection. It is vital to coordinate efforts among patients, nephrologists, vascular access surgeons, radiologists, nurses, nurse practitioners, and social workers to reduce the use of central venous catheters for dialysis treatment."
Study limitations included the inability to summarize SVI data below the county level, and the fact that bloodstream infection rates by individual SES factors could not be calculated because U.S. Census Bureau tract-level denominator data were unavailable.
"Strengthening hemodialysis bloodstream infection surveillance to more comprehensively assess social determinants of health would improve understanding of risk and address some of the limitations of this report," the authors concluded.
Novosad disclosed no relationships with industry. Co-authors disclosed support from the NIH, the Chan Zuckerberg Biohub Investigators Program, Merck, GlaxoSmithKline, Pfizer, and Sanofi Pasteur.
Morbidity and Mortality Weekly Report
Source Reference: Rha B, et al "Vital Signs: Health disparities in hemodialysis-associated staphylococcus aureus bloodstream infections -- United States, 2017-2020" MMWR 2023; DOI: 10.15585/mmwr.mm7206e1.