Vital Signs

Health Disparities in Hemodialysis-Associated Staphylococcus aureus Bloodstream Infections

United States, 2017-2020

Brian Rha, MD; Isaac See, MD; Lindsay Dunham, MPH, MSDA; Preeta K. Kutty, MD; Lauren Moccia, MA; Ibironke W. Apata, MD; Jennifer Ahern, PhD; Shelley Jung, PhD; Rongxia Li, PhD; Joelle Nadle, MPH; Susan Petit, MPH; Susan M. Ray, MD; Lee H. Harrison, MD; Carmen Bernu, MPH; Ruth Lynfield, MD; Ghinwa Dumyati, MD; Marissa Tracy, MPH; William Schaffner, MD; D. Cal Ham, MD; Shelley S. Magill, MD, PhD; Erin N. O'Leary, MPH; Jeneita Bell, MD; Arjun Srinivasan, MD; L. Clifford McDonald, MD; Jonathan R. Edwards, MStat; Shannon Novosad, MD

Disclosures

Morbidity and Mortality Weekly Report. 2023;72(6):153-159.

Abstract and Introduction

Abstract

Introduction: Racial and ethnic minorities are disproportionately affected by end-stage kidney disease (ESKD). ESKD patients on dialysis are at increased risk for Staphylococcus aureus bloodstream infections, but racial, ethnic, and socioeconomic disparities associated with this outcome are not well described.

Methods: Surveillance data from the 2020 National Healthcare Safety Network (NHSN) and the 2017–2020 Emerging Infections Program (EIP) were used to describe bloodstream infections among patients on hemodialysis (hemodialysis patients) and were linked to population-based data sources (CDC/Agency for Toxic Substances and Disease Registry [ATSDR] Social Vulnerability Index [SVI], United States Renal Data System [USRDS], and U.S. Census Bureau) to examine associations with race, ethnicity, and social determinants of health.

Results: In 2020, 4,840 dialysis facilities reported 14,822 bloodstream infections to NHSN; 34.2% were attributable to S. aureus. Among seven EIP sites, the S. aureus bloodstream infection rate during 2017–2020 was 100 times higher among hemodialysis patients (4,248 of 100,000 person-years) than among adults not on hemodialysis (42 of 100,000 person-years). Unadjusted S. aureus bloodstream infection rates were highest among non-Hispanic Black or African American (Black) and Hispanic or Latino (Hispanic) hemodialysis patients. Vascular access via central venous catheter was strongly associated with S. aureus bloodstream infections (NHSN: adjusted rate ratio [aRR] = 6.2; 95% CI = 5.7–6.7 versus fistula; EIP: aRR = 4.3; 95% CI = 3.9–4.8 versus fistula or graft). Adjusting for EIP site of residence, sex, and vascular access type, S. aureus bloodstream infection risk in EIP was highest in Hispanic patients (aRR = 1.4; 95% CI = 1.2–1.7 versus non-Hispanic White [White] patients), and patients aged 18–49 years (aRR = 1.7; 95% CI = 1.5–1.9 versus patients aged ≥65 years). Areas with higher poverty levels, crowding, and lower education levels accounted for disproportionately higher proportions of hemodialysis-associated S. aureus bloodstream infections.

Conclusions and Implications for Public Health Practice: Disparities exist in hemodialysis-associated S. aureus infections. 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.

Introduction

More than 800,000 persons in the United States live with ESKD, 70% of whom are treated with dialysis (89% hemodialysis and 11% peritoneal dialysis); 30% have a functioning kidney transplant.^[1] Race, ethnicity, and social determinants of health* affect development of ESKD.^[1–4] ESKD prevalence is fourfold higher among Black persons and more than twofold higher among Hispanic than among White persons,^[1] disparities which are thought to be attributable at least in part to underlying conditions such as hypertension and diabetes mellitus.^[1–3] 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.^[1,5–9] Black persons constitute 33% of all U.S. patients receiving dialysis,^[1] but only 12% of the U.S. population.^[10]

Infections are a leading cause of morbidity and mortality in hemodialysis patients.^[1] S. aureus is the most commonly isolated pathogen among bloodstream infections in hemodialysis patients reported to NHSN; 40% of those infections are methicillin resistant (MRSA)^†.^[11] Higher rates of invasive S. aureus infections have been observed in dialysis patients compared with nondialysis patients.^[12]

Type of hemodialysis access is a well-established risk factor for infections; risk is highest for central venous catheters (CVCs), lower for grafts, and lowest for fistulas.^[11] Although elevated rates have been reported for both invasive MRSA infections among Black dialysis patients^[13] and hospitalizations for dialysis-related infections among adult Black patients and older Hispanic patients (aged >60 years),^[14] the association among hemodialysis-related infections, race and ethnicity, and social determinants of health is largely undescribed. To identify groups experiencing high numbers and risk of infections and to determine which preventive interventions should be prioritized, this study used a national facility-level reporting system and a laboratory- and population-based surveillance network to understand markers of disparities in the risk for S. aureus bloodstream infections in hemodialysis patients. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.^§

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Abstract and Introduction
Methods
Results
Discussion
References
Sidebar

*https://www.cdc.gov/healthequity/whatis/
^† https://www.cdc.gov/dialysis/pdfs/BSI-NHSN-2014to2019-508.pdf
^§45 C.F.R. part 46.102(l)(2), 21 C.F.R. part 56; 42 U.S.C. Sect. 241(d); 5 U.S.C. Sect. 552a; 44 U.S.C. Sect. 3501 et seq.

Table 1. Independent factors associated with dialysis-associated *Staphylococcus aureus* bloodstream infection incidence* — National Healthcare Safety Network, United States, 2020
Characteristic	Likelihood ratio test^†		aRR (95% CI)	p-value
Characteristic	Chi-square	p-value	aRR (95% CI)	p-value
Vascular access type^§
Central venous catheter	2,090.2	<0.001	6.2 (5.7–6.7)	<0.001
Graft or other			2.2 (2.0–2.4)	<0.001
Fistula			Ref	—
Location/Hospital affiliation^¶
Hospital**	113.0	<0.001	1.5 (1.3–1.8)	<0.001
Freestanding	113.0	<0.001	Ref	—
Member of group or chain of dialysis centers^¶
No	111.7	<0.001	1.4 (1.2–1.7)	<0.001
Yes	111.7	<0.001	Ref	—
Written antibiotic use policy^¶
No	35.1	<0.001	1.3 (1.1–1.4)	<0.001
Yes	35.1	<0.001	Ref	—
Quartile of % of persons aged ≥65 yrs^††
Quartile 4: 75–100 (highest)	54.3	<0.001	1.4 (1.2–1.6)	<0.001
Quartile 3: 50–74			1.3 (1.2–1.5)	<0.001
Quartile 2: 25–49			1.3 (1.2–1.4)	<0.001
Quartile 1: 0–24 (lowest)			Ref	—

Abbreviations: aRR = adjusted rate ratio; ATSDR = Agency for Toxic Substances and Disease Registry; NHSN = National Healthcare Safety Network; Ref = referent group; SVI = Social Vulnerability Index.
*Negative binomial regression was used to fit this multivariate model.
^†Likelihood ratio test evaluates whether a factor is statistically significantly associated with Staphylococcus aureus bloodstream infection incidence. Additionally, Akaike and Bayesian information criteria and Wald and likelihood ratio chi-square tests were used to evaluate model fit. The best candidate model was validated using bootstrap resampling methods and independently assessed by two separate analysts.
^§Source of data was NHSN event surveillance.
^¶Source of data was NHSN Outpatient Dialysis Center Practices Survey. https://www.cdc.gov/nhsn/forms/57.500_outpatientdialysissurv_blank.pdf
**Location could be a hospital or a freestanding location owned by a hospital.
^††Source of data was CDC/ATSDR SVI.

Table 2. *Staphylococcus aureus* bloodstream infections associated with hemodialysis — Emerging Infections Program,* United States, 2017–2020
Characteristic	Univariate analysis			Multivariable analysis
Characteristic	No. of S. aureus bloodstream infections	No. of patient-years	Unadjusted rate^†	aRR^§ (95% CI)	p-value
Age groups, yrs^¶
18–49	736	11,848	6,212	1.7 (1.5–1.9)	<0.001
50–64	993	22,312	4,451	1.2 (1.1–1.4)	<0.001
≥65	1,071	31,758	3,372	Ref	—
Sex
Female	1,112**	28,239	3,938	Ref	—
Male	1,685	37,679	4,472	1.2 (1.1–1.4)	<0.001
EIP site
California	822	23,478	3,501	1.1 (0.9–1.4)	0.19
Connecticut	182	4,404	4,133	1.2 (1.0–1.5)	0.12
Georgia	393	6,218	6,320	2.0 (1.6–2.5)	<0.001
Maryland	741	15,022	4,933	1.4 (1.1–1.7)	0.003
New York	242	5,024	4,817	1.3 (1.0–1.6)	0.05
Tennessee	183	4,190	4,368	1.2 (1.0–1.5)	0.12
Minnesota	237	7,582	3,126	Ref	—
Race and ethnicity^††
Black, non-Hispanic	1,509	31,762	4,751	1.1 (0.9–1.2)	0.40
Hispanic	321	7,122	4,500	1.4 (1.2–1.7)	<0.001
White, non-Hispanic	687	17,764	3,866	Ref	—
Other, non-Hispanic	284	9,270	3,061	1.0 (0.8–1.2)	0.92
Vascular access types^§§
Central venous catheter	1,444	11,963	12,071	4.3 (3.9–4.8)	<0.001
Fistula or graft	1,303	48,631	2,679	Ref	—
Total	2,800	65,918	4,248	—	—

Abbreviations: aRR = adjusted rate ratio; EIP = Emerging Infections Program; Ref = referent group; S. aureus = Staphylococcus aureus.
*EIP data for January 1, 2017–December 31, 2020.
^†Per 100,000 hemodialysis person-years.
^§Adjusted for age, race and ethnicity, sex, vascular access type, and EIP site as appropriate.
^¶The median age of patients with hemodialysis S. aureus bacterial infection was 60 years (IQR = 49–70 years); the median age of those aged 18–49 years was 41 years.
**Sex was unknown for three patients.
^††Race and ethnicity were categorized as non-Hispanic Black or African American (Black), Hispanic or Latino (Hispanic), non-Hispanic White, and non-Hispanic other (includes patients with more than one race recorded). Race and ethnicity case counts are averaged over 10 imputations to account for missing values of race and ethnicity. The total sums to >2,800 because of rounding.
^§§Fifty-three cases had unknown vascular access type. The denominator includes 5,324 hemodialysis patient-years with unknown vascular access type.