Healthcare Infection Prevention-New surveillance data on hemodialysis project 78,000 patients acquire vascular access infections annually

Antibiotic use also critical in dialysis setting

Some 78,000 hemodialysis patients acquire vascular access infections each year, with 33,000 of them ill enough to require hospitalization, according to surveillance projections by the Centers for Disease Control and Prevention. Those data — extrapolated from the CDC's new surveillance system for hemodialysis settings — were presented recently in Toronto at the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC).

"Even if you could only prevent a small number of them, that would still save a lot of money for the country and [prevent] a lot of morbidity in the patients," says Jerome I. Tokars, MD, MPH, a medical epidemiologist who is directing the dialysis surveillance program at the CDC.

Extrapolating from data reported by the participating hemodialysis centers, the CDC also projected that 44,000 courses of outpatient antibiotics are being given to hemodialysis patients annually. (See chart, p. 2.) "Our sample is not necessarily representative, but this gives a ballpark idea," Tokars tells Healthcare Infection Prevention.

Infections and resulting use of antibiotics among hemodialysis patients have become increasingly important issues because this patient population appears to be more likely than others to develop vancomycin-intermediate-resistant Staphylococcus aureus (VISA). Earlier this year, the CDC described the fourth confirmed VISA case to appear in the United States, a 63-year-old woman who had a history of frequent hospitalizations for complications of hemodialysis-dependent end-stage renal disease.¹ As with other VISA cases, the patient had intermittent but prolonged therapy with vancomycin for methicillin-resistant S. aureus infection. Given such cases, some epidemiologists have predicted that much-feared, fully resistant staph strains will appear first in dialysis patients.

"Each course of antibiotics is just more pressure to select for antimicrobial-resistant pathogens," Tokars says. "Reducing that even by a small amount would be a worthwhile thing to do."

Crunching the numbers

Infections occur frequently in dialysis patients, but there have been few formal studies and no national surveillance data. The CDC launched a voluntary national surveillance system last year to study bacterial infections in hemodialysis outpatients. Participating hemodialysis centers report the number of patients, stratified by vascular access type, treated during the first week of the month (denominator) and infections associated with hospitalization or outpatient start of an intravenous antimicrobial agent. Access-related bacteremia (ARB) was defined as a positive blood culture without known source other than the vascular access. Vascular access infection (VAI) was defined as ARB or localized access symptoms (pus, redness, or increased swelling).

Among 70 centers reporting from August 1999 to June 2000, rates per 100 patient-months were 1.7 ARB (407 ARB during 23,588 patient-months) and 3.0 VAI (699/23,588). In an additional breakdown, the rate of VAI per 100 patient-months was:

• 0.44 (31/7,075) for patients with native fistulas;

• 1.18 (121/10,235) for grafts;

• 8.2 (443/5,382) for cuffed catheters;

• 11.6 (104/896) for noncuffed catheters.

"It is sort of unique to have rates that specific for vascular access. In the literature, you will basically see pooled rates," Tokars says. "But in order to really get a handle on what is going on, you need to have rates broken down into those four access types."

Overall, the 699 vascular access infections resulted in 399 outpatient IV antimicrobial courses, 300 hospitalizations, 202 losses of a catheter, and 45 losses of a fistula or graft. Additional analysis is under way to determine what factors cause the infections and how they might be prevented, he notes.

Also, the surveillance found two distinctive outlier groups, with nine centers having significantly lower vascular access infections and five centers having significantly higher rates. "We really need to go beyond what we have collected [thus far]," he says. "We're hoping to actually go to some of these centers and take pictures and video to see if we can really nail down why some places are so much different than others."

Source: Centers for Disease Control and Prevention, Hospital Infections Program, Atlanta.

Reference

1. Centers for Disease Control and Prevention. Staphylococcus aureus with reduced susceptibility to vancomycin Illinois, 1999 MMWR 2000; 48:1,165-1,167.