Infectious Complications From Vascular Access

Catheter-Related Blood Stream Infection Rate

CVCs account for an overwhelming majority of hemodialysis vascular access-related infections. In the United States, outpatient hemodialysis facilities report health-care-associated infection data to the Centers for Disease Control and Prevention (CDC) using an Internet-based surveillance system, the National Healthcare Safety Network (NHSN). The dialysis events reported to the NHSN include (1) positive blood cultures, (2) intravenous (IV) antibiotic starts, and (3) pus, redness, or increased swelling at the vascular access site, which would indicate a local infection. The NHSN data have been used by the Centers for Medicare and Medicaid Services (CMS) as part of the End-Stage Renal Disease Quality Incentive Program (ESRD QIP) since 2012 to assess facility performance. In the most recent NHSN 2014 surveillance report, which included data from over 6000 hemodialysis facilities, the rates of BSI were higher in patients who had a CVC compared with patients with other vascular access types. For CVC-dependent patients, the BSI rate was 2.16 per 100 patient months, whereas, in patients with AVFs and AVGs, the BSI rate was 0.26 and 0.39 per 100 patient-months, respectively ( Fig. 19.1 ). Although hemodialysis CVCs represented 19% of patient months reported, they accounted for 69% of all access-reported BSIs. Similar results were reported in a single-center study by Al-Solaiman et al., who reported that the rate of catheter-related BSI (CRBSI) was 3.17 per 1000 catheter-days, whereas the rate was 0.33 and 0.14 per 1000 access-days for AVG and AVF infections, respectively. Patients dialyzing with a CVC have a significantly higher risk of both fatal (2.12; 95% confidence interval [CI], 1.79–2.52) and nonfatal (4.66; 95% CI, 2.63–8.26) infections compared with patients using AVFs. This was observed in a study by Ravani et al., who performed a meta-analysis of 62 studies, which included over 500,000 participants.

The association of BSI risk with vascular access type was also reported in an incident older hemodialysis population (≥ 67 years). In a cohort of 2352 Medicare ESRD beneficiaries, Kazakova and others from the CDC observed that 17.2% of patient-initiated hemodialysis with an AVF, and 79.5% of patients started with a CVC over a 2-year period. Those starting hemodialysis with an AVF had a 61% lower risk for BSI compared with CVC-dependent patients (hazard ratio [HR], 0.39; 95% CI, 0.28–0.54) in an adjusted analysis.

In a Canadian observational cohort study of 1041 patients who initiated outpatient hemodialysis therapy with a tunneled catheter between 2004 and 2012, bacteremia occurred in 9% and 11% at 1 and 2 years, respectively. These were recently published data from an observational cohort study that included over 1000 patients by Poinen et al.

Hospitalizations for Catheter-Related Blood Stream Infections

The U.S. Renal Data System (USRDS) Annual Data Report (2018) identified a total of 870,783 hospitalizations in ESRD patients and 160,002 readmissions. When analyzed according to clinical classification, the most common principal diagnosis was septicemia, accounting for nearly 81,000 admissions (9.3%) and 14,500 readmissions (8.6%). In an analysis of infection-related hospitalization published in 2005 by Allon and colleagues for the Hemodialysis (HEMO) Study Group, only 21% of infection-related hospitalizations were access related. However, in the HEMO study the proportion of patients with CVC dependence was low, only 7.6%. Despite their relatively low prevalence, CVCs disproportionally accounted for 32% of patients requiring hospitalization for infection. Whereas, in a study which included only CVC-dependent patients ( n = 268), Al-Solaiman reported that the majority of infection-related hospitalizations were access-related infections (77%). Similarly, in the study by Poinen et al., bacteremia was responsible for 72% of all CVC-related hospitalizations. On average, hospitalization was needed in ~ 30% of CRBSI episodes.

The relationship between vascular access type and hospitalization rates in an incident cohort of older hemodialysis patients was recently evaluated by Kazakova and colleagues from the CDC. They observed that the risk of hospitalizations for BSI was 61% lower among AVF patients when compared to those with a CVC (HR, 0.39; 95% CI, 0.28–0.54). Hospitalization rates are 50%–70% higher in CVC-dependent hemodialysis patients than in those patients with an AVG or AVF. Fortunately, between 2007 and 2016, the rate of hospitalization for hemodialysis vascular access infections in the United States declined by 56%, from 0.26 to 0.13 hospitalizations per patient year; however, further improvement is needed.

Mortality Associated with Central Venous Catheters

Patients receiving hemodialysis with a CVC have a higher all-cause mortality compared to those with an AV access. In a large meta-analysis by Ravani et al., CVC-dependent patients were reported to have a > 50% higher risk for all-cause mortality (relative risk [RR], 1.53; 95% CI, 1.41–1.67) when compared to patients dialyzing with an AVF. Historically, the CVC was implicated as having a major role in patient mortality, presumably due to fatal infections. However, more recent studies have shed light on this relationship. In an interesting study of over 115,000 incident hemodialysis patients who were > 67 years old, Brown et al. compared mortality in three groups of patients: those initiating hemodialysis with an AVF, those dialyzing with a CVC after an AVF was attempted, and those dialyzing with a CVC who never had an AVF attempted. Patients initiating hemodialysis with a CVC after failed AVF placement had significantly lower mortality rates than the AVF-naïve CVC-dependent patients (HR, 0.66; 95% CI, 0.64–0.69). Similar findings were reported in a retrospective study by Quinn et al., which included 2300 incident Canadian hemodialysis patients who were ≥ 18 years of age. A significantly lower mortality was observed in patients < 65 years old (40% lower) and in patients ≥ 65 years (51% lower only in the first 2 years of hemodialysis) for whom a predialysis AVF was attempted, compared with those who did not. Patients who had undergone a predialysis AVF attempt were more likely to receive predialysis care and had higher body mass index, higher values for serum albumin, calcium, and blood hemoglobin, and a lower estimated glomerular filtration rate at dialysis initiation. They were also less likely to have congestive heart failure or start dialysis in the hospital or intensive care unit (ICU). In this study, a very small number of deaths, 14/617 (2.3%), were considered access related, and of the 14 patient deaths, majority (71.4%) were attributed to CVC complications. These data suggest that underlying patient factors and other determinants of patient selection for predialysis AVF surgery contribute to the excess mortality associated with CVC dependence.

Although CVC-dependent patients have a 1.5–2-fold higher risk of death caused by infection in comparison to those with AVGs and AVFs, the reported fatal infection incidence in episodes of CRBSI is relatively low. In an analysis of data from the HEMO study population published in 2005, Allon et al. reported that 3.8% of CVC-dependent patients hospitalized with first access–related infection died. In a prospective controlled study of 223 incident CVC-dependent hemodialysis patients presenting with their first episode of CRBSI, 4% of all patients died of sepsis within 90 days. In this 2006 study, Mokrzycki et al. observed that, over a 2-year study period, the use of a designated infection manager in outpatient hemodialysis facilities was associated with significantly lower risk of fatal infections. In the preintervention observation period, the incidence of sepsis-related death after CRBSI was 5% in all hemodialysis facilities. Thereafter, in facilities without an infection manager, the incidence of septic death remained similar, 6%. However, those facilities that assigned an infection manager reported 0 deaths due to sepsis ( p < 0.02). In another study, Mokrzycki et al. observed that episodes of CRBSI presenting with local CVC erythema and/or purulence, indicative of an exit or tunnel infection, were associated with a significantly higher rate of fatal infection (HR, 7; p < 0.001). In a Canadian study by Poinen et al., only 0.5% of deaths were directly attributable to sepsis associated with CRBSI at 1 year in a cohort of incident CVC-dependent hemodialysis patients.