Evidence Report/Technology Assessment: Number 6
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Under its Evidence-based Practice Program, the Agency for Health Care Policy and Research (AHCPR) is developing scientific information for other agencies and organizations on which to base clinical guidelines, performance measures, and other quality improvement tools. Contractor institutions review all relevant scientific literature on assigned clinical care topics and produce evidence reports and technology assessments, conduct research on methodologies and the effectiveness of their implementation, and participate in technical assistance activities.
Overview / Reporting the Evidence / Methodology / Findings / Future Research / Availability of Full Report
The objective was to analyze the evidence on selected aspects of the prevention and management of urinary tract infections in paralyzed persons. The two populations most commonly affected are persons having spinal cord injury (SCI) and people with multiple sclerosis (MS). Both of these conditions often have their onset in young adulthood. Eighty percent of persons with SCI experience a urinary tract infection (UTI) by their 16th year post-injury, and diseases of the urinary system are overall the fifth most common primary or secondary cause of death in this population. Between 70 to 90 percent of persons with MS develop bladder dysfunction over the course of their disease, placing them at increased risk for UTIs. Urinary complications are responsible for a large proportion of hospitalization-related episodes in these patient populations. UTI is the most frequent secondary medical complication reported by the federally designated Model Spinal Cord Injury Systems during acute care and rehabilitation, and UTI was the primary or secondary diagnosis for nearly one-third of hospitalizations of MS patients over the age of 65, according to 1989 Medicare data.
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Reporting the Evidence
The specific questions addressed in this report are:
- What combination of signs, symptoms, and laboratory findings are associated with risks to persons with paralysis due to neurogenic bladder?
- What are risk factors for recurrent UTIs?
- What are the risks and benefits of long-term use of antibiotic prophylaxis?
The literature review for the first key question was broad and included studies of both short and long-term risks as related to episodes of various combinations of signs, symptoms, and laboratory findings, such as the presence of fever, the level of bacteriuria, the type of organism, the presence of varying levels of pyuria, or some combination of those factors. For the literature search on risk factors for UTI, types of risk factors examined were socioeconomic status, insurance status, behavioral factors, personal hygiene, sex, and domicile, as well as intermediate risk factors of bladder management method (or drainage), time since injury, and level of functioning (or injury). Regarding prophylaxis, the efficacy of any oral antibiotic therapy and the efficacy of specific oral antibiotics were examined. All analyses were further stratified by acute versus non-acute SCI patients and by asymptomatic and symptomatic UTIs.
Study populations included adults and adolescents (13 years and older). In studies that had patient samples with spinal cord injury, the review focused on non-acute patients (defined as more than 90 days out from their injury) for all key questions, with the additional inclusion of studies of acute SCI patients for the analysis of antibiotic prophylaxis.
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A 13-member panel of experts, consumers, and a managed care organization representative was convened to focus the literature review on a set of key questions and to develop potential causal pathways for each question. Subsequently, a research librarian performed database searches of Medline (1966-January 1998) and Embase (1974-January 1998), using the terms urinary tract, urinary tract infections, bacteriuria, paraplegia, quadriplegia, spinal cord injuries, multiple sclerosis, neurogenic bladder, and neuropathic bladder. Case reports and animal studies were excluded. CINAHL (1982-July 1998) was also searched. Foreign language articles were not excluded from any searches. Some additional articles were identified by panel members and by review of citations of articles obtained from searches.
All titles were reviewed by two physicians, who then read abstracts of non-rejected titles, where available. Full-length articles were reviewed for the accepted abstracts and for titles with no abstract. Twelve translators assisted in the screening and evaluation of articles in 14 different foreign languages.
Selection criteria included human studies of adults and adolescents with neurogenic bladder due to spinal cord dysfunction, relevance to a key question, and inclusion of a potentially relevant outcome measure, such as bacteriuria or UTI. For the first two key questions, studies of acute SCI patients (those within the first 90 days following injury) were excluded. For prophylaxis of UTI, only randomized controlled trials were included; both acute and non-acute SCI study samples were included for this key question. Rejection criteria for all key questions were case reports, reviews, editorials, and letters; studies published before 1979 on risk factors for recurrent UTI were also excluded, because bladder management methods and their associated risks changed greatly with the introduction of intermittent catheterization at that time. As articles were reviewed, they were designated as addressing one of the key questions. Project investigators reviewed full-length articles and excluded those having insufficient data or not otherwise addressing a question. Data from remaining articles were extracted into evidence tables, and results summarized. Quality of controlled trials and of cohort studies was formally assessed.
A meta-analysis was conducted for the key question on benefits and harms of long-term use of antibiotic prophylaxis for UTI in people with neurogenic bladder due to spinal cord dysfunction. Steps included obtaining any additional information needed from authors of studies, identification of the outcomes and subgroups for analyses, formal assessment of evidence for publication bias, selection of an appropriate statistical pooling method, assessment and incorporation of heterogeneity, combination of data across studies, and execution of sensitivity analyses.
A draft evidence report was circulated for critique by the 13-member panel previously convened and by 7 additional content experts, methodologists, and a managed care organization representative. The meta-analysis was additionally reviewed by two outside experts in meta-analysis.
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- Study samples in most of the published literature were patients with SCI.
- Bacteriuria is a common occurrence; pyuria with bacteriuria may be associated with symptomatic infections, but these findings are also relatively common in asymptomatic patients.
- There are convergent data from several large cohort and case-control studies that the occurrence of febrile episodes in prior years is associated with a higher occurrence of upper urinary tract complications or abnormalities at long-term follow-up.
- The presence of certain bacteria or of multiple organisms early after spinal cord injury is associated with an approximately three-fold increased odds for developing bladder calculi at 2 years, but the presence of other signs and symptoms and treatment status were not included in the single study of this issue that was identified.
- Other evidence regarding the significance of signs, symptoms, and laboratory findings either is sparse or is inconclusive due to study design limitations.
- Indwelling catheterization is associated with more frequent infections than that involving intermittent catheterization, which in turn is associated with more frequent infections than methods not involving a catheter (However, severity of disease affects choice of method, particularly the alternatives involving use of a catheter versus no catheter.).
- The literature does not support firm conclusions regarding most other risk factors.
- Antibiotic prophylaxis significantly reduces bacteriuria among acute spinal cord injury patients (p <0.05), and there is a trend for reduction in bacteriuria among non-acute spinal cord patients (p = 0.06). however, antibiotic prophylaxis is not associated with a reduced number of symptomatic infections in the populations studied.
- Antibiotic prophylaxis results in a two-fold increase in the occurrence of antibiotic-resistant bacteria.
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Future research should focus in the areas of (1) prospective cohort studies to assess the short-term and long-term significance of signs, symptoms, and laboratory findings (level of bacteriuria and type of organism, pyuria, others); (2) large, multi-center, prospective cohort or randomized trial studies of risk factors for UTIs, particularly targeting potentially modifiable risk factors like behavioral factors and catheterization techniques; and (3) randomized controlled trials in the subgroup of patients who have frequent, recurrent urinary tract infections that limit their daily functioning and well-being. These studies should include both SCI and MS patients, where feasible, and should enroll a sufficient number of patients for adequate statistical power to detect meaningful clinical differences. In addition to traditional clinical measures, these studies should also measure quality-of-life outcomes and costs. State-of-the-art methods for maximizing the quality of the study designs and the rigor with which they are executed should be employed.
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Availability of the Full Report
The full Evidence Report from which this summary was taken was prepared for the Agency for Health Care Policy and Research by Southern California Evidence-based Practice Center/Rand Corporation, Santa Monica, CA, under contract No. 290-97-0001. The Evidence Report is archived online at: National Library of Medicine Bookshelf. Print copies are no longer available.
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AHCPR Publication No. 99-E007
Current as of January 1999