CTF Structured Abstract: Asymptomatic Bacteriuria in the Elderly

Canadian Task Force on Preventive Health Care

Structured Abstract

Please note: In 2003, the CTF updated its Grades of Recommendations to include an "I Recommendation" for situations where insufficient evidence exists to allow a recommendation to be made. (Formerly, these situations were captured under a "C Recommendation".) This change is not retroactive, and all "C Recommendations" made prior to 2003 have not been reevaluated in light of the new "I" recommendation grade. For a discussion of these recommendation grades, please link to the 2003 article in the Canadian Medical Association Journal here.

Screening for Asymptomatic Bacteriuria in the Elderly

Prepared by Lindsay E. Nicolle, MD, Associate Professor of Medicine/Medical Microbiology, University of Manitoba, Winnipeg

These recommendations were finalized by the Task Force in October 1993

Objective
Burden of Suffering
Options
Outcomes

Evidence
Values
Benefits, Harms, and Costs
Recommendations

Validation
Sponsors
Selected References

Objective

To make recommendations about screening for asymptomatic bacteriuria among institutionalized and non-institutionalized elderly men and women in Canada. This updates a 1979 report.

Burden of Suffering

The prevalence of bacteriuria in men and women aged 60 years and older is about 1-3% and 6-8%, respectively, while after age 80 these figures rise to 10% and 20 %. Studies have shown an even higher prevalence among institutionalized men and women, with rates from 20-30% and 30-50%, respectively. Bacteriuria in the elderly is usually asymptomatic. Morbidity with asymptomatic bacteriuria may include short-term complications of acute symptomatic infection and potential long-term complications of renal failure or mortality.

Urinary infection is the most common cause of bacteremia in both institutionalized and non-institutionalized elderly populations. The case fatality rate associated with bacteremic urinary infection in the elderly has been reported to be from 10-30%. Despite these observations urinary infection is rarely a direct cause of death in elderly subjects. The contribution of asymptomatic bacteriuria to mortality in the elderly has been controversial. There is no direct or indirect causal association of asymptomatic bacteriuria with mortality in elderly populations, nor is there any evidence that symptomatic bacteriuria, by itself, progresses to renal failure in this population.

Options

Culture and non-culture (e.g., leukocyte esterase/nitrate dipstick) urine screening measures with subsequent antimicrobial treatment (not specified).

Outcomes

Mortality, symptomatic episodes of bacteriuria (symptom presentation not described), reinfection/recurrence, and tendency to emergence of resistance to antimicrobial therapy.

Evidence

MEDLINE was searched up to March 1993 using the MeSH terms "urinary tract infections", "aged", "human" and "case reports".

Recommendations were graded as:

A Good evidence to support the recommendation that the condition be specifically considered in a PHE.

B Fair evidence to support the recommendation that the condition be specifically considered in a PHE.

C Poor evidence regarding inclusion or exclusion of the condition in a PHE, but recommendations may be made on other grounds.

D Fair evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

E Good evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

Quality of evidence was rated according to 5 levels:

I Evidence from at least 1 properly randomized controlled trial (RCT).

II-1 Evidence from well-designed controlled trials without randomization.

II-2 Evidence from well-designed cohort or case-control analytic studies, preferably from more than 1 centre or research group.

II-3 Evidence from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments could also be included here.

III Opinions of respected authorities, based on clinical experience, descriptive studies or reports of expert committees.

Values

The 13-member Task Force of experts in family medicine, geriatric medicine, pediatrics, psychiatry and epidemiology used an evidence-based method for evaluating the effectiveness of preventive health care interventions. Recommendations were not based on cost-effectiveness of options. Patient preferences were not discussed.

Background papers providing critical appraisal of the evidence and tentative recommendations prepared by the chapter author were pre-circulated to the members. Evidence for this topic was presented and deliberated upon in 1- to 2-day meetings, 2 to 3 times per year from January 1993 to June 1993. Consensus was reached on final recommendations.

Benefits, Harms, and Costs

A study of 124 asymptomatic, ambulatory elderly women not living in institutions found a non-significant decrease (16% to 8%) in symptomatic episodes 6 months after treatment. No difference in mortality occurred for treated and untreated groups (3.2% and 4.9%, p=0.66). A prospective cohort study of 234 asymptomatic elderly men not living in institutions reported a high rate of spontaneous recovery (76% of men with bacteriuria at screening) and a low frequency of symptom development.

In an RCT of 50 women who were institutionalized, 9 treated patients (39%) died compared with 4 untreated patients (18%). There were no differences in morbidity in treated and non-treated groups. Antimicrobial therapy was associated with increased drug side effects, reinfections and tendency to emergence of resistance. An RCT of 36 men living in institutions found no difference in mortality or morbidity in treated and non-treated groups.

Screening of patients with long-term indwelling catheters will not identify those at risk for morbidity. Antimicrobial therapy does not decrease morbidity, but may lead to resistant organisms.

Recommendations

Recommendation grade [A, B, C, D, E] and level of evidence [I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations in support of individual recommendations are identified in the guideline text.

There is insufficient evidence to recommend for or against urine screening by culture or leukocyte esterase/nitrite dipstick (and subsequent antimicrobial treatment) of asymptomatic elderly women who are ambulatory [C, I].
There is fair evidence to exclude screening or treatment of asymptomatic elderly men who are ambulatory [D, II-2].
There is good evidence not to include (in the PHE) screening and treatment of elderly women or men who live in institutions, or persons with long term indwelling catheters [E, I].

Validation

This report was externally peer-reviewed.

Selected References

Source Document

Nicolle L.E. Screening for asymptomatic bacteriuria in the elderly. In: Canadian Task Force on the Periodic Health Examination. Canadian Guide to Clinical Preventive Health Care. Ottawa: Health Canada, 1994; 966-73.

Other

Canadian Task Force on the Periodic Health Examination. The periodic health examination. Can Med Assoc J. 1979;121:1193-254.

Link to Full Text of this review

Link to Summary Table of Recommendations of this review

Link to Selected References list of this review

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A	Good evidence to support the recommendation that the condition be specifically considered in a PHE.
B	Fair evidence to support the recommendation that the condition be specifically considered in a PHE.
C	Poor evidence regarding inclusion or exclusion of the condition in a PHE, but recommendations may be made on other grounds.
D	Fair evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.
E	Good evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE.

I	Evidence from at least 1 properly randomized controlled trial (RCT).
II-1	Evidence from well-designed controlled trials without randomization.
II-2	Evidence from well-designed cohort or case-control analytic studies, preferably from more than 1 centre or research group.
II-3	Evidence from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments could also be included here.
III	Opinions of respected authorities, based on clinical experience, descriptive studies or reports of expert committees.