Does Eradicating Bacteriuria Affect the Severity of Chronic Urinary Incontinence in Nursing Home Residents?

Urinary incontinence is a multibillion-dollar health problem that afflicts almost 60% of some 2 million residents of the 20 000 nursing homes in the United States. Bacteriuria is also prevalent in this population, and the two conditions commonly coexist [1]. Incontinent nursing home residents are frequently prescribed antimicrobial agents for urinary tract infections, but the quality and appropriateness of such prescriptions have been questioned [2-5]. Unnecessary antimicrobial treatment may result in the undesired development of resistant organisms and substantial unnecessary morbidity and health care expenditure. Well-designed clinical trials have documented that treating asymptomatic bacteriuria in the nursing home population has no significant effects on morbidity and mortality and that it actually leads to the development of strains of bacteria that are resistant to commonly prescribed antimicrobial agents [6, 7]. However, no studies have carefully examined the effects of eradicating bacteriuria on the severity of incontinence in this population. In a longitudinal study of a cohort of older women, Boscia and colleagues [8] found no difference in self-reported symptoms of incontinence in patients with and without bacteriuria. This was, however, a study of bacteriuria and not of incontinence, and the participants had, on average, mild incontinence [9]. In one study of behavioral therapy for incontinence in nursing home residents, incontinence appeared to worsen in several of the study participants when bacteriuria developed [10]. Epidemiologic studies from Europe have reached different conclusions about the association between bacteriuria and incontinence in the geriatric population [11, 12]. Despite a lack of definitive data on the relation of bacteriuria to the pathogenesis and severity of incontinence in the nursing home population, recently implemented federal guidelines for the care of incontinence in nursing homes (Resident Assessment Protocol) [13] suggest that bacteriuria should be treated only when symptoms of urinary tract infection other than stable incontinence are present. If eradicating bacteriuria makes the bladder less irritable in this patient population, then the severity of incontinence and the use of expensive adult diapers might be reduced [14]. If, however, eradicating bacteriuria has no effect on the severity of incontinence, no rationale would exist for exposing incontinent nursing home residents with bacteriuria to the potential added morbidity and expense of antimicrobial therapy. We conducted a clinical trial to determine whether eradicating bacteriuria affects the severity of incontinence among nursing home residents. We defined bacteriuria as would a practicing clinician in a nursing home rather than by the strict definition used in most studies of the epidemiology of asymptomatic bacteriuria (that is, two consecutive cultures with growth of more than 105 colony-forming units [CFUs] of the same organism). We hypothesized that sterilizing the urine would have no short-term effect on the severity of chronic incontinence in this population. Methods Setting Our study was the first phase of a multifaceted clinical trial addressing the assessment and treatment of incontinence in nursing homes. It was done in one nonprofit and five proprietary nursing homes located close to the offices of the University of California at Los Angeles Borun Center for Gerontological Research at the Jewish Home for the Aging. The nursing homes had a total of 1011 beds (range, 99 to 256 beds) and a total of 832 residents. Patients We identified potential patients by asking nursing home staff to identify residents who were incontinent of urine on a regular basis [that is, several times per week to several times per day]. Patients were excluded if 1) their care was being reimbursed by Medicare [indicating either short-term rehabilitation or medical instability]; 2) their prognosis, as determined by the research staff nurse, was so poor that they would probably not live at least 3 to 4 months to complete the protocol; 3) daytime incontinence was not documented by random-hour checks for wetness [described below]; 4) the resident had a permanent indwelling bladder catheter; 5) the resident failed a cognitive status screening test [to pass, the resident had to either say their name or reliably point to one of two objects]; and 6) the resident manifested a severe behavioral disturbance, such as physical aggression or verbal abusiveness, during the wet-checking procedures. Informed consent was obtained from residents who could provide it (as determined by a facility nurse or social worker). If the resident was not capable of consenting, their assent was obtained (by describing a simple version of the protocol and then observing their cooperation as the protocol was initiated), and consent was then obtained from a responsible party. Procedures All patients for whom informed consent was obtained had a focused history, functional status assessment, cognitive assessment with the 30-point Mini-Mental State Examination, targeted physical examination, urinalysis, and urine culture. For the functional assessment, research staff used the Multidimensional Observational Scale for the Elderly Subject [15] to interview nursing home staff who knew the residents well. (When our study was implemented, the Minimum Data Set was not yet available.) Research staff used a standardized scale (Performance on Timed Toileting Instrument [16]) to objectively assess functional status specifically related to toileting skills. The physical examination was done by research staff and a physician coinvestigator and included abdominal, genital, pelvic, rectal, and neurologic examinations. Research staff collected urine from female patients by cleaning the perineal area with Betadine and having them void into a fracture bed pan or measuring hat that had been cleaned with an antiseptic solution. We compared the culture results of urine samples obtained by this procedure to urine samples obtained by catheterization in 101 of our female patients [17]. The prevalence of bacteriuria in the catheterized specimens was 29%. The sensitivity, specificity, and positive and negative predictive values of this procedure in detecting bacteriuria (with a catheter specimen used as the criterion standard) are 90%, 92%, 81%, and 95%, respectively. For men who could not void voluntarily, we used a previously validated technique that involved cleaning the glans penis with Betadine, applying a clean condom catheter, and processing the first voided specimen [18]. Urine specimens were subjected to screening tests done by research staff (including a dipstick method for leukocyte esterase and nitrite and a rapid enzyme-based test for bacteriuria [Uriscreen, Ventrex Laboratories, Portland, Maine]). A bioclinical laboratory used standard techniques to do a microscopic urinalysis and a urine culture and sensitivity test. We defined pyuria as the presence of more than 10 leukocytes per high-power field on microscopic examination of spun urine. Cultured specimens that grew more than 50 000 CFUs were considered to have significant growth. If significant growth of one or more urinary pathogens occurred on a second specimen, the patient was considered to be bacteriuric. Patients whose urine had significant growth of organisms that are not typically pathogens (for example, lactobacillus and -streptococcus) were not considered to be bacteriuric. Our quantitative definition of bacteriuria differs from the standard definition (presence of more than 100 000 CFUs) that has been used in most epidemiologic studies and intervention trials. However, there is controversy about the clinical significance of lower levels of growth [19], and in some studies in the elderly, bacteriuria has been defined as growth of less than 100 000 CFUs [20, 21]. We used the cutoff of 50 000 CFUs because our clinical laboratory reported results at this level, and we believe that most clinicians who practice in nursing homes would consider this to be significant growth when making decisions about treatment. Less than 10% of our cultures that were considered to have significant bacteriuria had growth of more than 50 000 CFUs. In addition, each patient identified as bacteriuric who had growth of more than 50 000 CFUs on one culture did have a second culture with growth of more than 100 000 CFUs; the only exceptions were two patients whose urine samples before treatment were collected by catheterization (see below). Most specimens obtained after antimicrobial treatment were collected by catheterization, which was done for a determination of postvoid residual volume in the second phase of the longer ongoing clinical trial. Six patients whose urine was initially not bacteriuric by the criteria outlined above were considered to be bacteriuric on the basis of the catheterized specimen and were enrolled in the antimicrobial trial. For these patients, follow-up urine samples were collected by the methods described above rather than by repeat catheterization. Eradication of bacteriuria was documented by culture in all but seven cases; in these cases, the screening tests were used to document that bacteriuria had been eradicated. We have shown that in our population, the presence of at least two negative results on these screening tests has a negative predictive value of more than 90% [22]. Bacteriuric patients were randomly assigned to receive either immediate treatment or delayed treatment (which was administered 2 to 3 weeks after the immediate treatment group had been treated) with a 7-day course of norfloxacin, 400 mg orally twice daily. In three cases, the organism or organisms were not susceptible to norfloxacin, and another antimicrobial agent (trimethoprim-sulfamethoxazole) was used on the basis of results of the sensitivity testing. Wet checks, the outcome measure used in our study and described in detail below, w