Bloodstream Infection Risk Associated With Race, SES Among Patients on Hemodialysis

Risk of hemodialysis-associated Staphylococcus aureus (S aureus) bloodstream infections is greater among minority patients and those of lower socioeconomic status, according to the CDC’s latest Morbidity and Mortality Weekly Report.

End-stage kidney disease (ESKD) affects more than 800,000 people in the United States, in which minority populations are disproportionately impacted. Compared with White individuals, ESKD prevalence is 4-fold higher among Black persons and more than 2-fold higher among Hispanic/Latino people.

“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,” wrote researchers. “Black persons constitute 33% of all US patients receiving dialysis, but only 12% of the US population.”

For patients with ESKD on hemodialysis, infection serves as the leading cause of morbidity and mortality. S aureus is the most commonly isolated pathogen among bloodstream infections in patients on hemodialysis, and is more likely to occur in dialysis vs nondialysis patients. Approximately 40% of these infections are methicillin resistant (MRSA), which can prove difficult to treat and increase risk of morbidity and mortality.

“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 (age > 60 years), the association among hemodialysis-related infections, race and ethnicity, and social determinants of health is largely undescribed,” noted researchers.

Utilizing surveillance data from the 2020 National Healthcare Safety Network (NHSN) and the 2017-2020 Emerging Infections Program (EIP), authors sought to examine risk for S aureus bloodstream infections in patients on hemodialysis and potential markers for disparities.

For the analysis, S aureus bloodstream infection was defined as a new positive blood culture test result reported from outpatient dialysis facilities during 2020. Bloodstream infections and patient-months were categorized by type of vascular access: central venous catheters (CVC), fistula, and graft or other.

Data from the NHSN and EIP databases were linked with population-based data sources (CDC/Agency for Toxic Substances and Disease Registry Social Vulnerability Index, United States Renal Data System [USRDS], and US Census Bureau) to examine associations with race, ethnicity, and social determinants of health (eg, measures of poverty, crowding, and education).

Unadjusted S aureus bloodstream infection rates among patients on hemodialysis were stratified by the characteristics described in the USRDS data, including sex, age group (18-49, 50-64, and ≥ 65 years), race and ethnicity, and vascular access type. Moreover, to handle overdispersion, negative binomial regression was performed to determine adjusted risk ratio (aRR) for age, race and ethnicity, sex, vascular access type, and EIP site.

During 2020, a total of 7097 dialysis facilities were included in this analysis, of which 4840 dialysis facilities (68.2%) reported 14,822 bloodstream infections, and S aureus was isolated from 5070 (34.2%). Among reported S. aureus bloodstream infections, 2602 (51.3%) were identified as methicillin-sensitive and 1923 (37.9%) as MRSA.

Among 7 EIP sites, the S aureus bloodstream infection rate during 2017-2020 was indicated to be 100 times higher among patients on hemodialysis (4248 of 100,000 person-years) compared with adults not on hemodialysis (42 of 100,000 person-years).

By race and ethnicity, results from unadjusted S aureus bloodstream infection rates were shown to be highest among non-Hispanic Black and Hispanic/Latino patients on hemodialysis. Other variables associated with higher rates included male sex, younger age groups, CVC access, and specific surveillance sites. Vascular access via CVC in particular was strongly associated with S aureus bloodstream infections (NHSN: aRR, 6.2; 95% CI, 5.7-6.7 vs fistula; EIP: aRR, 4.3; 95% CI, 3.9-4.8 vs fistula or graft).

After adjusting for EIP site of residence, sex, and vascular access type, S aureus bloodstream infection risk in EIP was found to be highest in Hispanic patients vs non-Hispanic White patients (aRR, 1.4; 95% CI, 1.2-1.7), and patients aged 18-49 years vs those aged 65 years or older (aRR, 1.7; 95% CI, 1.5-1.9).

Areas with higher poverty levels, crowding, and lower education levels accounted for disproportionately higher proportions of hemodialysis-associated S aureus bloodstream infections.

Researchers noted that the complex relationships among age, race and ethnicity, social determinants of health, and hemodialysis-associated infection risk warrant additional study. Limitations of the study findings included the use of 2020 NHSN facility-reported bloodstream infection data that were not patient-specific and could not be summarized below the county level.

“Disparities exist in hemodialysis-associated S. aureus infections,” they concluded. “Health care providers and public health professionals should prioritize prevention and optimized treatment of ESKD, identify and address barriers to lower-risk vascular access placement, and implement established best practices to prevent bloodstream infections.”

Reference

Rha B, See I, Dunham L, et al. Vital Signs: Health disparities in hemodialysis-associated Staphylococcus aureus bloodstream infections—United States, 2017–2020. MMWR Morb Mortal Wkly Rep. Published online February 6, 2023. doi:10.15585/mmwr.mm7206e1