Pyuria Detection Using A Dipstick Applied to Urine In Incontinence Pads Susan Midthun

Ruth Paur

U

The purpose of this study was to determine whether pressing a dipstick into a pad within 2 hours of urine saturation detected pyuria as effectively as immersing a dipstick in a urine specimen. Sensitivity, specificity, and positive and negative predictive values indicated that results of the pad method were as effective as those of direct dipstick into clean-catch urine in detecting pyuria. In the elderly, sensitivity of the pad method was 100%, indicating this would be an effective method for initial assessment of pyuria.

rinary tract infections (UTIs) are the most common nosocomial infection in the nursing home population (Beck-Sague et al., 1994; Farber, Brennen, Puntereri, & Brody, 1984; Jacobson & Strausbaugh, 1990). In older adults, bacteria in the urine (bacteriuria) without symptoms and WBCs in urine (pyuria) is considered benign and transient (Boscia, Abrutyn, Levison, Pitsakis, & Kaye, 1989; Gleckman, 1992). Determining symptomatic infection may be difficult because UTI symptoms may be chronic or atypical; they can also be masked by disease processes or medications (Abrutyn et al., 1996; Barkham, Martin, & Eykyn, 1996; Boscia et al., 1989; Yoshikawa, 1984). The presence of pyuria, however, is an objective evaluation for a UTI. It is indicative of an Susan Midthun, MS, RN, is a Research Nurse, Clinical Laboratory Sciences Program, Department of Pathology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND. Ruth Paur, MS, MT (ASCP), is the Interim Clinical Laboratory Science Program Director, Clinical Science Program, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND. A. Wayne Bruce, PhD, is the Director of Continuing Medical Education, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND. Note: This study was funded by the Retirement Research Foundation, Chicago, IL: Grant No. 2001-087.

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A. Wayne Bruce

Introduction Determination of pyuria in incontinent elderly individuals by dipstick applied to incontinence pads could eliminate unnecessary testing and facilitate the rate at which persons receive early nursing interventions for potential UTIs. Objective Using a descriptive design and convenience sample of 467 adults, the study sought to determine if leukocyte esterase results of a dipstick pressed into urine in an incontinence pad would identify pyuria as effectively as results of a dipstick immersed directly into a urine specimen. Method Clean catch urine was collected in a “hat.” Within an hour post-void, some of the specimen was analyzed microscopically for WBCs by a clinical laboratory scientist to serve as the gold standard for accuracy for all dipstick results. A Chemstrip 10® dipstick was used by a research nurse to check for the presence of leukocyte esterase, by dipping it directly into the obtained specimen. Urine was then poured into an incontinence pad and a Chemstrip 10 was pressed into the urine-soaked pads immediately. A Chemstrip 10 was, again, pressed into the pad urine after 2 hours. Results When compared to laboratory microscopy, sensitivity, specificity, and positive and negative predictive values indicated that dipstick results of the pad

method, both initially and at 2 hours, were as effective as those of a dipstick immersed in the urine specimen. Over half of all positive results were false, though, and would require further evaluation. However, in those greater than 65 years old, all individuals with pyuria were correctly identified and all negative results indicated a lack of pyuria using any of the three dipstick methods. Conclusions There is a lack of consensus among health care professionals about what constitutes a UTI in an elderly individual. If pyuria is required for a UTI to be present in this population, then negative results of a dipstick pressed into an incontinence pad within 2 hours of urine saturation would be a good indication of the absence of a UTI. Positive results, however, would require further analysis, as over half of these outcomes were false. “The value of a positive test should be judged not on its ability to detect UTIs but on the additional information it provides in evaluating the clinical picture” (White & Kunin, 1993, p. 230). Further studies may find positive results of the dipstick/pad method combined with other clinical findings could aide in the decision to send urine for laboratory analysis. Positive results may also help provide additional information to the clinical picture and help in managing UTIs in the elderly.The dipstick/pad method could be used in the initial assessment of an incontinent individual who may have difficulty giving a urine specimen on-site at the nursing home where laboratory facilities may be lacking.

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infection and a need for further laboratory analysis (Norman, Yamamura, & Yoshikawa, 1986; Pfaller, Ringenberg, Rames, Hegeman, & Koontz, 1987; Stamm, 1983; Wigton et al., 1985). The level of pyuria may indicate an infection’s virulence (Nicolle, 2001). Pyuria has also been associated with a lower longterm survival rate among the elderly (Heinamaki, Haavisto, Hakulinen, Mattila, & Rajala, 1986). Assessing pyuria in the elderly nursing home population, therefore, may be an important factor in identifying UTIs and improving outcomes in this population. In the laboratory, the traditional setting of pyuria analysis, dipstick assessment of leukocyte esterase is used to initially screen urine specimens for this condition. “Leukocyte esterase, an enzyme present in WBCs, reacts with a reagent impregnated into the dipstick pad producing a blue color…” (Pappas, 1991, p. 315). Unfortunately, the nursing home may not have laboratory facilities readily available (Ouslander, 1989). This may lead to a delay in diagnosis, a factor leading to poorer outcomes in the elderly. There are other difficulties in assessing elderly individuals for UTIs. Urine specimens can be difficult to obtain, especially in the incontinent elderly. Urine in pads, however, may afford an alternative to clean-catch or midstream specimens for evaluating bacteriuria and pyuria. Studies of urine extracted from pads that do not contain gel have found bacteriuria detection similar to that of traditional urine specimens (Ahmad, Vickers, Campbell, Coulthard, & Pedler, 1991; Cohen et al., 1997; Vernon, Redfern, Pedlar, Lambert, & Coulthard, 1994). These studies also found

reduced WBC counts compared to conventional urine specimens, leading to the hypothesis that pad material retains or breaks apart WBCs. Although WBCs may be affected by pad urine, leukocyte esterase may not. One study found that while WBCs may be retained in the pad and unavailable for microscopy, soluble leukocyte esterase from pad urine could be detected by a test strip (Macfarlane, Houghton, & Hughes, 1999). Incontinence pads are often monitored every 2 hours. If leukocyte esterase results from a dipstick pressed into pad urine within a 2-hour time frame are similar to leukocyte results from a dipstick immersed in a urine specimen, the former would afford an easy, quick, and inexpensive alternative method for initially assessing pyuria. This method could be used at nursing homes and offer useful, objective data for the residents’ clinical picture.

Purpose The aim of this study was to compare leukocyte esterase results from a urine dipstick pressed into a pad within 2 hours of urine saturation to results obtained from a urine dipstick immersed in a clean-catch urine specimen for the purpose of detecting pyuria.

Method Sample. A convenience sample was taken from clinic patients and staff and eldercare and nursing home residents who met the following criteria: they were at least 18 years old, able to give informed consent, and antibiotic-free 7 days before the study. No other history was taken. Most clinic patients included in the study had a urinalysis ordered. Reasons for the

Acknowledgments. The authors wish to thank the Retirement Research Foundation, Chicago, for funding this study. The authors would also like to thank Dr. Glenda Lindseth, Dr. Steven Schultz, Dr. Marvin Cooley, Dr. John Williams, Dr. Julie Anderson, Virginia Eslinger, and the physicians, nurse practitioners, physicians assistants, and nurses who allowed us access to their patients. Finally, the authors would like to thank the nursing home, eldercare facility, laboratory, and clinic staff who so graciously shared their space with us.

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urinalysis included ruling out UTIs or post-UTI treatment, as well as a need to perform tests due to employment physicals, pregnancy, or diabetic screening. Informed consent was obtained. Procedures conformed to the University of North Dakota’s Institutional Review Board’s ethical guidelines. Procedure. Participants were instructed in a clean-catch technique. Urine specimens were collected from a new “hat” placed in the toilet. A minimum of 30 ml was required to be included in the analysis. A time limit of 1 hour post-voiding was imposed on the dipstick urinalysis of the clean-catch specimen, the initial dipstick pad test, and the WBC microscopy. Urine specimens meeting the study criteria were tested in the following manner: A dipstick was immersed in the urine specimen and leukocyte esterase results were read according to manufacturer’s guidelines (dipstick/ua). After removing enough urine for microscopic analysis, a portion of the specimen sufficient to wet the pad was poured into a middle section of a Dry Comfort® incontinence pad (SCA Hygiene, Eddystone, PA). The principal components of the pad are wood pulp and a superabsorbent polymer. The upper portion of a urine dipstick, Chemstrip 10 with SG®, containing test sections for specific gravity and leukocyte esterase, was pressed into the wettest part of the pad with two thumbs for 10 seconds. Results were read according to manufacturer’s guidelines (dipstick/pad 0h). Two hours after voiding (plus or minus 15 minutes), a urine dipstick was pressed for 10 seconds into a wet section of the pad that had not been used for the initial dipstick test. Results were read using the same guidelines (dipstick/pad 2h). To insure that negative results were not due to an insufficient amount of urine coming in contact with the leukocyte esterase test section, a color change in the specific gravity test section was also required. The leukocyte esterase results of

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all three methods were read as negative, trace, 1+, and 2+. Negative and trace results were considered negative (neg), and 1+ and 2+ were considered positive (pos). The gold standard was determined by urine microscopy performed in the following manner: Five ml of the urine specimen were centrifuged for 5 minutes at 400x g. Four and one-half ml of the supernatant were removed and the sediment was suspended in the remaining half ml sample. A drop of this suspension was placed on a slide and viewed under 450x light microscopy. White blood cell results of < 10 were considered negative and those > 10 were considered positive. This designation conforms to the “CDC definition for nosocomial infection, 1988” classification of pyuria indicative of a UTI (Garner, Jarvis, Emori, Horan, & Hughes, 1988) Analyses. Results of each dipstick method were compared to the gold standard. These were designated true positive for the method if the dipstick and microscopy were both positive; true negative if the dipstick and microscopy were both negative; false positive if the dipstick was positive but the microscopy was negative; and false negative if the dipstick was negative but the microscopy was positive. To compare the three dipstick methods — dipstick/ua, dipstick/pad 0h, and dipstick/pad 2h — several analyses were then performed: sensitivity, specificity, positive and negative predictive value, and efficiency. Sensitivity is the percentage of specimens positive for pyuria that the method correctly identifies as positive. “Tests with high sensitivity (> 99%) can be used to exclude the presence of disease” (Weissfeld, Sahm, & Forbes, 1998, p. 61). Calculations for this are shown in Figure 1. Specificity is the percentage of specimens that are negative that the test correctly identifies as negative (see Figure 2). Positive predictive value (PPV) is the percentage of true

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Figure 1. High-Sensitivity Calculations true positive Sensitivity =

X 100 true positive + false negative

Figure 2. Specificity Tests true negative Specificity =

X 100 true negative + false positive

Figure 3. Predictive Values true positive PPV =

X 100 true positive + false positive true negative

NPV =

X 100 true negative + false negative

Figure 4. Specificity Tests true positive + true negative Efficiency =

X 100 true positive + true negative + false positive + false negative

positive results of all positive results and “measures the probability that a positive result indicates the presence of disease” (Weissfeld et al., 1998, p. 61). Negative predictive value (NPV) is the percentage of true negative results of all negative results and “measures the probability that a negative result indicates the absence of disease” (Weissfeld et al., 1998, p. 61). They are calculated in Figure 3. Efficiency is the “percentage of test results that are correctly identified by the test” (Weissfeld et al., 1998, p. 61). This is shown in Figure 4.

Results Consent for participation in the study was obtained from 581 individuals. Of these, 114 were

removed from the study for reasons that included insufficient urine, greater than 1 hour elapsed before the specimen could be tested, or urine contained squamous cells in a sufficient number (too numerous to count) to interfere with a WBC microscopy result. Of the remaining 467 participants, 133 (28.5%) were male and 334 (71.5%) were female. The age range was 18 to 95, with a mean age of 51.2 years (+ SD 20.3). Positive WBC results were found in 41 (8.8%) individuals. Table 1 reports the results of the three methods. Sensitivity indicates the number of individuals with the condition who were correctly identified (DawsonSaunders & Trapp, 1994). All three methods effectively identi-

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Table 1. Comparison of Leukocyte Esterase Results to WBC Microscopy Results Dipstick/UA Results Positive

Dipstick/Pad 0h Results Dipstick/Pad 2h Results

Negative

Positive

Negative

Positive

Negative

Total

Microscopy Results Positive

40

1

40

1

40

1

41

Negative

67

359

68

358

56

370

426

Total

107

360

108

359

96

371

467

Dipstick/ua: Sensitivity 97.6%; Specificity 84.3%; PPV 37.4%; NPV 99.7%; Efficiency 85.4% Dipstick/pad 0h: Sensitivity 97.6%; Specificity 84%; PPV 37%; NPV 99.7%; Efficiency 85.2% Dipstick/pad 2h: Sensitivity 97.6%; Specificity 86.9%; PPV 41.7%; NPV 99.7%; Efficiency 88% PPV = Positive Predictive Value NPV = Negative Predictive Value

Table 2. Comparison of Leukkocyte Esterase Results to WBC Microscopy Results of Individuals > 65 Years of Age Dipstick/UA Results Positive

Dipstick/Pad 0h Results Dipstick/Pad 2h Results

Negative

Positive

Negative

Positive

Negative

Total

Microscopy Results Positive

20

0

20

0

20

0

20

Negative

22

92

26

88

22

92

114

Total

42

92

46

88

42

92

134

Dipstick/ua: Sensitivity 100%; Specificity 80.7%; PPV 47.6%; NPV 100%; Efficiency 83.6% Dipstick/pad 0h: Sensitivity 100%; Specificity 77.2%; PPV 43.5%; NPV 100%; Efficiency 80.6% Dipstick/pad 2h: Sensitivity 100%; Specificity 80.7%; PPV 47.6%; NPV 100%; Efficiency 83.6% PPV = Positive Predictive Value NPV = Negative Predictive Value

fied individuals with pyuria (97.6%). Specificity indicates the number of individuals without the condition that were correctly identified (Dawson-Saunders & Trapp, 1994). Results for all three methods were similar, ranging from 84% to 86.9%. Positive predictive value (the percentage of patients with a positive test result who actually have the condition) and negative predictive value (the number of individuals testing negative who

do not have the condition) take into account the prevalence of the condition in the study population (Norman et al., 1986; Weissfeld et al., 1998). The PPV varied slightly among the three methods, none achieving more than 42%. For all methods, the NPV was 99.7%; almost all individuals testing negative did not have pyuria. Efficiency measures the number of individuals both with and without the condition who were correctly identified

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compared to the total sample. Again, the dipstick/pad 2h method was slightly better than the other two methods, identifying almost 90% of individuals correctly. In other words, the dipstick/pad method initially and at 2 hours was as effective as the traditional dipstick urinalysis in pyuria assessment. The analyses used in this study are influenced by the prevalence of the condition in the population (Lachs et al.,

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1992). In this study ages ranged from 18 to 95 years, and 8.8% were found to be pyuric. The elderly have a greater incidence of pyuria (Rodgers et al., 1991). Therefore analysis was also calculated for those individuals > 65. Of the 134 elderly in this study, 14.9% were pyuric. The data for these individuals are presented in Table 2.

Discussion Comparing Tables 1 and 2, using any of the three methods, all older adults with pyuria were correctly identified. In other words, there were no false negatives (sensitivity = 100%). As all negative results were indicative of urine without WBCs, the NPV was 100% for the elderly. However, the number of falsepositive compared to true-negative results increased in all methods (see Table 2), with the greatest increase occurring in the two pad methods. This decreased specificity. Interestingly, the PPV increased in all three methods, perhaps due to the increased prevalence of pyuria in this population. Sensitivities of other studies of leukocyte esterase detection for pyuria using urine specimens have ranged from 36% to 100%, with specificities from 71.4% to 94.3% (Christenson, Tucker, & Allen, 1985; Edwards, van der Voort, Newcombe, Thayer, & Jones, 1997; Herily, Wilkerson, & Roy, 1984; Sheer, 1987; Wilkins, Ratcliff, & Roberts, 1985; Zaman, Borremans, Verhaegen, Verbist, & Blanckaert, 1998). Sensitivities (97.6% to 100%) in this study were better than in most of the previous studies of pyuria detection using leukocyte esterase results. Specificities (77.2% to 86.9%), in general, were lower than in other studies. Several factors can affect the outcomes of WBC detection using leukocyte esterase results. The incidence of pyuria in the population already has been mentioned. Improvement in the technology of the dipstick will change results over time (Hamilton-Miller, 1999). Factors influencing the dipstick results include consider-

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ing trace leukocyte esterase results positive or the variability of reading color changes in the leukocyte esterase test strip. Factors can also influence the gold standard. These consist of using centrifuged versus uncentrifuged urine or the number of WBCs considered positive (Sheer, 1987; Wilkens et al., 1985). For example, some studies have considered > 5 WBCs a positive result (Christianson et al., 1985; Herlihy et al., 1984; Zaman et al., 1998). If > 5 WBCs were determined to be in the positive range, some of the initial false positives (the 1+ leukocyte esterase dipstick results of urines with 5 to 9 WBCs) would now be true positives. This would improve the PPV and specificity. However, decreasing the number of WBCs considered to be positive would also mean some of the initial true negative results (negative or trace leukocyte esterase results with urines of 5 to 9 WBCs) would now be false negatives. This would decrease the NPV and sensitivity. A similar manipulation could be performed by considering trace leukocyte esterase results as positive. It may initially appear that the PPV is the most important factor of this type of test, a positive value indicating a positive result. However, in this setting, sensitivity and NPV are the more important in that, though there were many false-positive results, no true positives were missed in those > 65 years old (no false negatives). Although some individuals without infection were falsely identified as pyuric, no infected elderly individuals failed to be identified; therefore, this test has the potential to be used to screen urines. Further evaluation would be needed for positive individuals because of the number of false-positive results. All negative leukocyte esterase dipstick/pad results were true negative. Therefore, if pyuria is required for a diagnosis of a UTI, as is often the case, a negative dipstick/pad result would be a good predictor that a UTI was not

present and further analysis would not be necessary.

Limitations Analyses used in this study are dependent on the sample studied. Results of the incontinent, nursing home elderly (who have a higher incidence of pyuria) would differ. Methods pertaining to WBC and dipstick analysis may affect the results as well. Commercial pads comprise various materials which may affect leukocyte esterase results differently (Edwards et al., 1997). Other brands of urine dipsticks use different scales, and thus may result in different findings as well. Although the dipstick/pad method is easy to use, leukocyte esterase results of some urines fall between the positive (1+) and negative (trace) color of the Chemstrip® color chart and require expertise to interpret correctly. Additional studies using this method will be needed to resolve this problem.

Conclusions In those > 18 years, the dipstick/pad method, both initially and at 2 hours, was as effective as the dipstick/ua method in assessing pyuria. The dipstick/pad 2h was the most effective for reasons that are not apparent. Among the elderly with a greater incidence of pyuria, the sensitivity, PPV, and NPV of all three methods improved. The frequency of false positives in the elderly increased, more so with the two dipstick/pad methods, decreasing specificity. Even so, the dipstick/pad 2h was as specific as the dipstick/ua and as effective in predicting positive results. This study indicates that leukocyte esterase results of a dipstick pressed into a pad within 2 hours of voiding are as effective as the traditional dipstick/ua method for pyuria detection.

Nursing Implications A perfect test for a disease would be inexpensive, fast, and easy to use with no possibility of

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reader variability. Positive results would always indicate that the condition was present, and negative ones would indicate its absence. Interventions using the test would always be appropriate for all individuals. In the present application, there is an added difficulty independent of the test itself. That is, there is a lack of consensus among health care professionals regarding not only what constitutes a UTI in an older adult, but what actions have positive, long-term benefits for the patient and the population in general (for example, not increasing antibiotic-resistant stains of bacteria). Given these caveats, further studies may find the dipstick/pad method of pyuria identification beneficial to the incontinent nursing home population in several ways. If pyuria is an indicator of poorer outcomes in incontinent nursing home older adults, the dipstick/pad method could be used to screen for this condition. At present this is not recommended. In this study, a negative result was 100% predictive of a lack of pyuria. Although no test is always correct, a negative result from the pad method would be fairly indicative of apyuria. If apyuria is indicative of no UTI, then a negative LE dipstick/pad result within 2 hours of urine saturation would be reasonably indicative of the absence of a UTI. All individuals with pyuria in this study were identified by positive dipstick/pad leukocyte esterase. However, there were a substantial number of false positives, and, even with true positive results, there are reasons other than a UTI for an inflammatory response (White & Kunin, 1993). Therefore, “the value of a positive test should be judged not on its ability to detect UTIs but on the additional information it provides in evaluating the clinical picture” (White & Kunin, 1993, p. 230). Leukocyte esterase results are frequently used in combination with other results (Edwards et al., 1997). In addition to a positive leukocyte

esterase result, a positive dipstick nitrite test, acute onset of UTI symptoms, and/or a decline in ADLs (analyses that are available to the nurse at the point of care) would add credibility to the possibility of a UTI and need for laboratory analysis. The importance of the dipstick/pad method for pyuria detection will vary among individuals. Studies may show that some elderly who have continually positive results do not benefit from analysis. Instead, a positive result may be more helpful when seen in the context of a change from a previous negative result. The dipstick/pad method is as effective as the dipstick/ua method for assessing pyuria. Further studies will determine this method’s effectiveness for improving outcomes among incontinent older adults. • References Abrutyn, E., Berlin, J., Mossey, J., Pitsakis, P., Levison, M., & Kaye, D. (1996). Does treatment of asymptomatic bacteriuria in older ambulatory women reduce subsequent symptoms of urinary tract infection? Journal of the American Geriatrics Society, 44(4), 293-295. Ahmad, T., Vickers, D., Campbell, S., Coulthard, M., & Pedler, S. (1991). Urine collection from disposable nappies. The Lancet, 338(8768), 674-676. Barkham, T., Martin, F., & Eykyn, S. (1996). Delay in diagnosis of bacteraemic urinary tract infection in elderly patients. Age and Ageing, 25(2), 130-132. Beck-Sague, C., Villarino, E., Giuliano, D., Welbel, S., Latts, L., et al. (1994). Infectious diseases and deaths among nursing home residents: Results of surveillance in 13 nursing homes. Infection Control and Hospital Epidemiology, 15(7), 494496. Boscia, J., Abrutyn, E., Levison, M., Pitsakis, P., & Kaye, D. (1989). Pyuria and asymptomatic bacteriuria in elderly ambulatory women. Annals of Internal Medicine, 110(5), 404405. Christianson, R., Tucker, J., & Allen, E. (1985). Results of dipstick tests, visual inspection, microscopic examination of urine sediment and microbiological cultures of urine compared for simplifying urinalysis. Clinical Chemistry, 31(3), 448-450. Cohen, H., Woloch, B., Linder, N., Vardi, P., Barzilai, A., & Tel-Hoshomer, I. (1997). Urine samples from disposal

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diapers: An accurate method for urine cultures. The Journal of Family Practice, 44(3), 290-292. Dawson-Saunders, B., & Trapp R. (1994). Evaluating diagnostic procedures. In Basic and clinical biostatistics (2nd ed.), (pp. 232-247). Norwalk, CT: Appleton & Lange. Edwards, A., van der Voort, J., Newcombe, R., Thayer, H., & Jones, K. (1997). A urine analysis suitable for children’s nappies. Journal of Clinical Pathology, 50(7), 569-571. Farber, B., Brennen, C., Puntereri, A., & Brody, J. (1984). A prospective study of nosocomial infections in a chronic care facility. Journal of the American Geriatrics Society, 32(7), 499-502. Garner, J., Jarvis, W., Emori, T., Horan T., & Hughes, J. (1988) CDC definitions for nosocomial infections, 1988. Journal of Infection Control, 16(3), 128-140. Gleckman, R. (1992). Urinary tract infection. Clinics in Geriatric Medicine, 8(4), 793-803. Hamilton-Miller, J. (1999). Issues in urinary tract infections in the elderly. World Journal of Urology, 17(6), 396401. Heinamaki, P., Haavisto, M., Hakulinen T., Mattila, K., & Rajala. (1986). Mortality in relation to urinary characteristics in the very aged. Gerontology, 32(3), 167-171. Herliy, R., Wilkerson, R., & Roy, J. (1984). New and rapid method for detection of pyuria and leukocyte esterase reaction. Urology, 23(2), 148-149. Jacobson, C., & Strausbaugh, L. (1990). Incidence and impact of infection in a nursing home care unit. American Journal of Infection Control, 18(3), 151-158. Lachs, M., Nachamkin, I., Edelstein, P., Goldman, J., Feinstein, A., & Schwartz, J. (1992). Spectrum bias in the evaluation of diagnostic tests: Lessons from the rapid dipstick test for urinary tract infection. Annals of Internal Medicine, 117(2),135-140. Macfarlane, P., Houghton, C., & Hughes, C. (1999). Pad urine collection for early childhood urinary-tract infection. The Lancet, 354(9178), 571. Nicolle, L. (2001). Urinary tract pathogens in complicated infection in elderly individuals. Journal of Infectious Diseases, 183(Suppl. 1), S5-8. Norman, D., Yamamura, R. & Yoshikawa, T. (1986). Pyuria: Its predictive value of asymptomatic bacteriuria in ambulatory elderly men. Journal of Urology, 135(3), 520-522. Ouslander, J. (1989). Medical care in the nursing home. Journal of the American Medical Association, 262(18), 2582-2590. Pappas, P. (1991). Laboratory in the diagnosis and management of urinary tract infections. Medical Clinics of North America, 75(2), 313-325.

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Research continued from page 435 Pfaller, M., Ringenberg, B., Rames, L., Hegeman, J., & Koontz, F. (1987). The usefulness of screening tests for pyuria in combination with culture in the diagnosis of urinary tract infection. Diagnostic Microbiology and Infectious Disease, 6(3), 207215. Rodgers, K., Nicolle, L., McIntyre, M., Harding, G., Hoban, H., & Murray, D. (1991). Pyuria in institutionalized elderly subjects. Canadian Journal of Infectious Disease, 2(4), 142-146. Sheer D. (1987). The detection of leukocyte esterase activity in urine with a new reagent strip. American Journal of Clinical Pathology, 87(1), 86-93. Stamm, W. (1983). Measurement of pyuria and its relation to bacteriuria. The American Journal of Medicine, 75(Suppl. 1B), 53-58. Vernon, S., Redfern, A., Pedlar, S., Lambert, H., & Coulthard, M. (1994). Urine collection on sanitary towels. Letter to the editor. The Lancet, 344(8922), 612. Weissfeld, A., Sahm, D., & Forbes, B. (Eds.). (1998). Bailey and Scott’s diagnostic microbiology (10th ed.) St. Louis: Mosby, Inc. White, L., & Kunin, C. (1993). Leukocyte esterase tests pyuria not bacteriuria. Letter to Editor. Annals of Internal Medicine, 118(3), 230. Wigton, R., Hoellerich, V., Ornato, J., Leu, V., Mazotta, L., & Cheng, I. (1985). Use of clinical findings in the diagnosis of urinary tract infection in women. Archives of Internal Medicine, 145(12), 2222-2227. Wilkins, E., Ratcliff, J., & Roberts, C. (1985). Leukocyte esterase-nitrite screening method for pyuria and bacteriuria. Journal of Clinical Pathology, 38(12), 1342-1345. Yoshikawa, T. (1984). Unique aspects of urinary tract infection in the geriatric population. Gerontology, 30(5), 339-344. Zaman, Z., Borremans, A., Verhaegen, J., Verbist, L., & Blanckaert, N. (1998). Disappointing dipstick screening for urinary tract infections in hospital inpatients. Journal of Clinical Pathology, 51(6), 471-472.

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