Nosocomial Infections in Elderly Patients in the United States, 1986-1990 T. GRACE EMORI, R.N., MS., SHAILEN N. BANERJEE, Ph.D., DAVID H. CULVER, Ph.D., ROBERT P. GAYNES, M.D., TERESA C. HORAN, M.P.H., c.I.c., JONATHAN R. EDWARDS, MS., WILLIAM R. JARVIS, M.D., JAMES S. TOLSON, B.S., TONYA S. HENDERSON,B.S., WILLIAM J. MARTONE, M.D., JAMES M. HUGHES, M.D., and the NATIONAL NOSOCOMIAL~NFECTIONSSURVEILLANCESYSTEM, At/anta,Georgia
We analyzed 101,479 nosocomial infections in 75,398 adult patients ( 2 15 years) that were reported to the National Nosocomial Infections Surveillance (NNIS) system between 1986 and 1990 by 89 hospitals using the NNIS hospital-wide surveillance component. Overall, 54% of the infections occurred in elderly patients ( 2 65 years). In the elderly, 44% of the infections were urinary tract infections CUTIs), 18% were pneumonias, 11% were surgical wound infections (SWIs), 8% were bloodstream infections (BSIs), and the remainder were infections at other sites. When we compared the infections in elderly patients with those in younger adult patients, ages 15 to 64 years, a far greater percentage of the infections in elderly patients were UTIs, and there were more pneumonias than SW&. Elderly and younger patients with ventilator-associated pneumonia were about 1.5 times more likely to develop a secondary BSI than those with pneumonia not associated with ventilator use. When the pathogens isolated from the infections were compared to those reported to the NNIS system in 1984, the percentage that were coagulase-negative staphylococci had increased in both elderly and younger patients. The patient died in 12% of all of the infections. Surveillance personnel reported that 54% of the infections in elderly infected patients who died were related to death compared with 59% in younger infected patients who died. When the infection was related to the patient’s death, it was most often pneumonia or a BSI. The
From the Hospital infections Program, and the Office of the Director, National Center for Infectious Diseases, Centers for Disease Control, US. Public Health Service, Department of Health and Human Services, Atlanta, Georgia 30333. Requests for reprints should be addressed to T. Grace Emori, R.N., MS., Hospital Infections Program, Mailstop A07, Centers for Disease Control, 1600 Clifton Road, Atlanta, Georgia 30333.
September
16,
1991
risk of an infection-related death was significantly higher when the infected patient developed a secondary BSI. Infection prevention efforts should target infections that occur frequently, are amenable to intervention, and have an adverse outcome.
Id age is a recognized risk factor for infection. Hospitalization compounds the risk of infection by exposing patients to invasive procedures in an environment abundant with virulent and antibiotic-resistant pathogens. As the United States population ages, the proportion of hospitalized patients who are elderly will increase. Nosocomial infection (NI) rates are expected to rise concomitantly unless infection control programs recognize the challenges presented by elderly patients. The purpose of this article is to provide background information on the nature of NIs in the elderly in order to help to develop infection control measures that will lower their risk of NI.
0
METHODS The data used in this analysis were collected from 1986 through 1990 by 89 hospitals participating in the National Nosocomial Infections Surveillance (NNIS) system that followed the hospital-wide surveillance component [ 11. Because no age-specific denominator data are collected in the hospital-wide surveillance component, infection rates could not be calculated. An infected patient was deemed to have been exposed to a medical device, either an indwelling urinary catheter, peripheral vascular line, central vascular line, hyperalimentation therapy, or mechanically assisted ventilation (ventilator), when the device had been used on the patient within 48 hours before the onset of the infection at a related site, Although there are no specific NNIS criteria for determining the relationship of an infection to the death of the patient, when infected patients died, surveillance personnel used information from the patient’s medical records and other sources to assess this relationship subjectively. They reported their conclusion The American
Journal
of Medicine
Volume
91 (suppl3B)
38-2898
CONFERENCE
ON NOSOCOMIAL
INFECTIONS
/ EMORI
ET AL
RESULTS
PNEU
SWI Infection Site
SSI
During the period of this report, 101,479 infections were identified in 75,398 patients; 54% of the infections were in elderly patients. The percentage of the infections that were in elderly patients was about the same each year. Urinary tract infections (UTIs) accounted for almost half of the infections in elderly patients followed by pneumonias, surgical wound infections (SWIs), and bloodstream infections (BSIs) (Figure 1). Of the most common pathogens isolated from infections in elderly patients, Escherichia coli occurred most frequently (15%), followed by Pseudomonas aeruginosa (12%), Enterococcus spp (ll%), Staphylococcus aureus (9%), coagulase-negative staphylococci (CNS) and Enterobacter spp (7% each), and Candida albicans (6%). The most common pathogens isolated in elderly patients at the four major infection sites are shown in Figure 2. We found some differences in the frequency of infections at each of the sites in elderly and younger infected patients (Figure 1). Compared with younger infected patients, elderly infected patients had a higher percentage of UTIs, but younger infected patients had a higher percentage of SWIs than elderly infected patients. The rank order and percent distribution of the pathogens isolated from UTIs and BSIs in elderly and younger patients were almost the same. For SWIs and pneumonias, the distribution of pathogens was also similar; however, in younger patients with SWI, S. aureus was more common (18%) than
OTH
Figure 1. Percent distribution of nosocomial infections by site In elderly patients (2 65 years) compared with younger adult patients (15 to 64 years), NNIS system, 1986-1990. BSI = primary bloodstream infection; OTH = infections in other sites; PNEU = pneumonia; SWI = surgical wound infection; UTI = urinary tract infection.
that the infection either caused the death, contributed to the death, was unrelated, or that the relationship was unknown. In this analysis, infections that surveillance personnel said caused or contributed to the patient’s death were considered to be “related” to the death. We defined elderly patients as those aged 2 65 years and younger patients as those aged 15-64 years. The distribution of NI in elderly patients was contrasted with those in younger patients and with the distribution of nosocomial pathogens reported to the NNIS system in 1984, the last published overview of NNIS data [21. UTI
PNEU Enterokq$e 00
K pneumoniae 8% E. coli 6%
6%
SW1
BSI S. aureus
Figure 2. Most frequently isolated pathogens from the major infection sites in elderly patients (265 years), NNIS system, 1986-1990. BSI = primary bloodstream infection; OTH = infections in other sites; PNEU = pneumonia; SWI = surgical wound infection; UTI = urinary tract infection.
3B-290s
September
16, 1991
The American
Journal
of Medicine
Volume
91 (suppl
3B)
CONFERENCE ON NOSOCOMIAL INFECTIONS / EMORI ET AL TABLE I Infections in Elderly Patients (165 years) and Younger Adult Patients (15-64 years) Exposedto High-RiskMed Elderly Patients Site
Medical Device
Urinary tract Pneumonia (lung) Bloodstream Infection
Indwelling urinary catheter Ventilator Hyperalimentation Central line Peripheral line
Exposed (%)
Number Infections at Site
ii
23,422 9,456 4,375
1986-199,
System,
Younger Patients Number Exposed (%) Infections at Site 78* o*
RW&
1
4,159
2 61
I Devices,NNlS
5:259 4,977 4,975
4,159
*Significantdifference between elderly and younger patienis (p tO.OOO1l.
Enterococcus spp (13%), and in pneumonias, S. aureus was slightly more common (16%) than P. aeruginosa (15%). Exposure to certain high-risk medical devices was common among infected patients. As shown in Table I, almost all of the patients with a UT1 had an indwelling urinary catheter, and the majority of patients with a BSI had a central vascular or peripheral line. Elderly patients with a UT1 were significantly more likely than younger patients with a UT1 to have an indwelling urinary catheter (p
We analyzed 101,479 nosocomial infections in 75,398 adult patients ( 2 15 years) that were reported to the National Nosocomial Infections Surveillance (NNIS) system between 1986 and 1990 by 89 hospitals using the NNIS hospital-wide surveillance component. Overall, 54% of the infections occurred in elderly patients ( 2 65 years). In the elderly, 44% of the infections were urinary tract infections CUTIs), 18% were pneumonias, 11% were surgical wound infections (SWIs), 8% were bloodstream infections (BSIs), and the remainder were infections at other sites. When we compared the infections in elderly patients with those in younger adult patients, ages 15 to 64 years, a far greater percentage of the infections in elderly patients were UTIs, and there were more pneumonias than SW&. Elderly and younger patients with ventilator-associated pneumonia were about 1.5 times more likely to develop a secondary BSI than those with pneumonia not associated with ventilator use. When the pathogens isolated from the infections were compared to those reported to the NNIS system in 1984, the percentage that were coagulase-negative staphylococci had increased in both elderly and younger patients. The patient died in 12% of all of the infections. Surveillance personnel reported that 54% of the infections in elderly infected patients who died were related to death compared with 59% in younger infected patients who died. When the infection was related to the patient’s death, it was most often pneumonia or a BSI. The
From the Hospital infections Program, and the Office of the Director, National Center for Infectious Diseases, Centers for Disease Control, US. Public Health Service, Department of Health and Human Services, Atlanta, Georgia 30333. Requests for reprints should be addressed to T. Grace Emori, R.N., MS., Hospital Infections Program, Mailstop A07, Centers for Disease Control, 1600 Clifton Road, Atlanta, Georgia 30333.
September
16,
1991
risk of an infection-related death was significantly higher when the infected patient developed a secondary BSI. Infection prevention efforts should target infections that occur frequently, are amenable to intervention, and have an adverse outcome.
Id age is a recognized risk factor for infection. Hospitalization compounds the risk of infection by exposing patients to invasive procedures in an environment abundant with virulent and antibiotic-resistant pathogens. As the United States population ages, the proportion of hospitalized patients who are elderly will increase. Nosocomial infection (NI) rates are expected to rise concomitantly unless infection control programs recognize the challenges presented by elderly patients. The purpose of this article is to provide background information on the nature of NIs in the elderly in order to help to develop infection control measures that will lower their risk of NI.
0
METHODS The data used in this analysis were collected from 1986 through 1990 by 89 hospitals participating in the National Nosocomial Infections Surveillance (NNIS) system that followed the hospital-wide surveillance component [ 11. Because no age-specific denominator data are collected in the hospital-wide surveillance component, infection rates could not be calculated. An infected patient was deemed to have been exposed to a medical device, either an indwelling urinary catheter, peripheral vascular line, central vascular line, hyperalimentation therapy, or mechanically assisted ventilation (ventilator), when the device had been used on the patient within 48 hours before the onset of the infection at a related site, Although there are no specific NNIS criteria for determining the relationship of an infection to the death of the patient, when infected patients died, surveillance personnel used information from the patient’s medical records and other sources to assess this relationship subjectively. They reported their conclusion The American
Journal
of Medicine
Volume
91 (suppl3B)
38-2898
CONFERENCE
ON NOSOCOMIAL
INFECTIONS
/ EMORI
ET AL
RESULTS
PNEU
SWI Infection Site
SSI
During the period of this report, 101,479 infections were identified in 75,398 patients; 54% of the infections were in elderly patients. The percentage of the infections that were in elderly patients was about the same each year. Urinary tract infections (UTIs) accounted for almost half of the infections in elderly patients followed by pneumonias, surgical wound infections (SWIs), and bloodstream infections (BSIs) (Figure 1). Of the most common pathogens isolated from infections in elderly patients, Escherichia coli occurred most frequently (15%), followed by Pseudomonas aeruginosa (12%), Enterococcus spp (ll%), Staphylococcus aureus (9%), coagulase-negative staphylococci (CNS) and Enterobacter spp (7% each), and Candida albicans (6%). The most common pathogens isolated in elderly patients at the four major infection sites are shown in Figure 2. We found some differences in the frequency of infections at each of the sites in elderly and younger infected patients (Figure 1). Compared with younger infected patients, elderly infected patients had a higher percentage of UTIs, but younger infected patients had a higher percentage of SWIs than elderly infected patients. The rank order and percent distribution of the pathogens isolated from UTIs and BSIs in elderly and younger patients were almost the same. For SWIs and pneumonias, the distribution of pathogens was also similar; however, in younger patients with SWI, S. aureus was more common (18%) than
OTH
Figure 1. Percent distribution of nosocomial infections by site In elderly patients (2 65 years) compared with younger adult patients (15 to 64 years), NNIS system, 1986-1990. BSI = primary bloodstream infection; OTH = infections in other sites; PNEU = pneumonia; SWI = surgical wound infection; UTI = urinary tract infection.
that the infection either caused the death, contributed to the death, was unrelated, or that the relationship was unknown. In this analysis, infections that surveillance personnel said caused or contributed to the patient’s death were considered to be “related” to the death. We defined elderly patients as those aged 2 65 years and younger patients as those aged 15-64 years. The distribution of NI in elderly patients was contrasted with those in younger patients and with the distribution of nosocomial pathogens reported to the NNIS system in 1984, the last published overview of NNIS data [21. UTI
PNEU Enterokq$e 00
K pneumoniae 8% E. coli 6%
6%
SW1
BSI S. aureus
Figure 2. Most frequently isolated pathogens from the major infection sites in elderly patients (265 years), NNIS system, 1986-1990. BSI = primary bloodstream infection; OTH = infections in other sites; PNEU = pneumonia; SWI = surgical wound infection; UTI = urinary tract infection.
3B-290s
September
16, 1991
The American
Journal
of Medicine
Volume
91 (suppl
3B)
CONFERENCE ON NOSOCOMIAL INFECTIONS / EMORI ET AL TABLE I Infections in Elderly Patients (165 years) and Younger Adult Patients (15-64 years) Exposedto High-RiskMed Elderly Patients Site
Medical Device
Urinary tract Pneumonia (lung) Bloodstream Infection
Indwelling urinary catheter Ventilator Hyperalimentation Central line Peripheral line
Exposed (%)
Number Infections at Site
ii
23,422 9,456 4,375
1986-199,
System,
Younger Patients Number Exposed (%) Infections at Site 78* o*
RW&
1
4,159
2 61
I Devices,NNlS
5:259 4,977 4,975
4,159
*Significantdifference between elderly and younger patienis (p tO.OOO1l.
Enterococcus spp (13%), and in pneumonias, S. aureus was slightly more common (16%) than P. aeruginosa (15%). Exposure to certain high-risk medical devices was common among infected patients. As shown in Table I, almost all of the patients with a UT1 had an indwelling urinary catheter, and the majority of patients with a BSI had a central vascular or peripheral line. Elderly patients with a UT1 were significantly more likely than younger patients with a UT1 to have an indwelling urinary catheter (p
