Clinical Review & Education
JAMA Diagnostic Test Interpretation
Tests for Urinary Tract Infection in Nursing Home Residents Manisha Juthani-Mehta, MD; Ann Datunashvili, MD; Mary Tinetti, MD
A nursing home resident in her 80s has a history of falls, cognitive impairment, and incontinence. In the past 2 years, she was thought to have a urinary tract infection (UTI) on 8 occasions and received antibiotic therapy 6 times. Symptoms that triggered an evaluation for UTI included increased confusion, urinary frequency, cloudy urine, lethargy, hallucinations, and falls. On this occasion, the family reports that she “doesn’t look right,” but the nursing staff states she is not confused. The patient reports no dysuria or abdominal pain but does chronically complain of voiding frequently. She is afebrile with no abdominal, suprapubic, or flank tenderness, but her urine has a foul odor. A catheterized urine specimen is obtained and results of urinalysis are reported (Table). The urine culture reveals more than 100 000 colony-forming units (CFUs) per milliliter of Escherichia coli, which is sensitive to all antibiotics except ampicillin. Table. Case Patient’s Urinalysis Test Results Result
Reference Standards/Ranges
Color
Yellow, hazy
Yellow
Specific gravity
1.005
1.005-1.030
pH
7
5.5-7.5
Blood
1+
Negative
Protein
Negative
Negative
Nitrite
1+
Negative
Leukocyte esterase
3+
Negative
Bacteria
3+
None-few/hpf
White blood cells
40-100/hpf
0-5/hpf
Red blood cells
2/hpf
0-5/hpf
Epithelial cells
0-5/lpf
None-few/lpf
HOW DO YOU INTERPRET THESE TEST RESULTS?
A. The patient has asymptomatic pyuria and bacteriuria. B. The patient has a UTI because of chronic incontinence and a positive urine culture. C. A positive urinalysis and urine culture are always a UTI. D. Since the patient has a history of recurrent UTIs, these urine test results indicate that she has another UTI.
Abbreviations: hpf, high-power field; lpf, low-power field.
Answer A. The patient has asymptomatic pyuria and bacteriuria.
Test Characteristics The evaluation of suspected UTI involves identifying specific signs or symptoms associated with symptomatic UTI and appropriate interpretation of 3 potential tests: bedside urinary dipstick, urinalysis, and urine culture. The dipstick has different test characterisRelated article page 1677 tics depending on the population studied and the patient’s clinical presentation.1 In adults Quiz at jama.com aged 65 years or older, the sensitivity of the dipstick (positive to leukocyte esterase, nitrite, or both) for urine culture with more than 100 000 CFU/mL ranges from 65%to100%;specificity,20%to77%;positivepredictivevalue(PPV), 31% to 45%; negative predictive value (NPV), 90% to 100%; positive likelihood ratio (LR+), 1.25 to 2.8; and negative likelihood ratio (LR−), 0 to 0.46.2-4 When leukocyte esterase, nitrite, or both are positive at any level, dipstick results are not helpful in the evaluation of UTI because of low PPV. Because the NPV of the dipstick is high in nursing home residents, a negative test result for leukocyte esterase and nitrite suggests that further evaluation for UTI is unnecessary.
On urinalysis, more than 10 white blood cells per high-power field (WBC/hpf) is an accepted threshold for pyuria required for UTI diagnosis in an older adult. 5 The sensitivity of more than 10 WBC/hpf for more than 100 000 CFU/mL is 78%; specificity, 63%; PPV, 64%; NPV, 74%; LR+, 2.11; and LR−, 0.35. 6 Pyuria should only be used to confirm a clinical diagnosis of UTI. Test characteristics of the urine culture are not available because urine culture results (ⱖ100 000 CFU/mL) are part of the criterion standard and accepted definition of UTI in older adults.5,7 Based on the Medicare fee schedule, costs are as follows: urinary dipstick, $4.32; urinalysis, $2.96 to $4.15; basic urine culture, $11.01; bacterial identification $7.06 to $27.36; and antibiotic susceptibilities $6.48 to $11.80.8
Application of Test Result to This Patient The urinalysis and urine culture results are positive in this patient. However, asymptomatic pyuria (45%) and asymptomatic bacteriuria (25%-50%) are highly prevalent in female nursing home residents and are not sufficient to make the diagnosis of UTI.9 The clinical criteria for symptomatic UTI in older women include 2 or more of the following signs and symptoms: fever, worsened urinary urgency or frequency, acute dysuria, suprapubic tenderness, or costovertebral angle pain or tenderness.5 Laboratory tests confirming
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Clinical Review & Education JAMA Diagnostic Test Interpretation
the diagnosis include bacteriuria (ⱖ100 000 CFU/mL) and pyuria (ⱖ10 WBC/hpf). With none of the clinical criteria for symptomatic UTI present, this patient has asymptomatic bacteriuria and pyuria. Three clinical features, acute dysuria, change in character of urine, and change in mental status, were associated with bacteriuria plus pyuria in elderly nursing home residents7; however, both change in mental status and change in character of urine can occur in bacteriuric and nonbacteriuric nursing home residents.10 Bacteriuria was present in 39% of female nursing home residents with restlessness, 41% with fatigue, 45% with confusion, 39% with aggressiveness, 60% with “not being herself,” 42% with urgency, 42% with dysuria, and 50% with fever.9 As in this patient, it should be anticipated that if a urinalysis and urine culture are performed, pyuria and bacteriuria would be present. Given the clinical presentation of this patient, these results represent asymptomatic pyuria and bacteriuria, which do not require antibiotic therapy.
What Are Alternative Diagnostic Testing Approaches? Since the patient only had change in character of urine, a preferable approach would be to initiate hydration first to determine if foul-smelling urine resolves. If it persists and change in mental status develops, a thorough evaluation of other potential etiologies should be pursued first (eg, discontinuation of diuretics or adjustment of medications affecting mentation). If both symptoms persist, performing a dipstick test is warranted.5 In this patient, evalu-
Patient Outcome This patient was treated with cefuroxime for 7 days. It was unclear whether treatment produced any improvement in clinical status.
Clinical Bottom Line: • Clinical criteria for symptomatic UTI include 2 or more of the following signs and symptoms: fever, worsened urinary urgency or frequency, acute dysuria, suprapubic tenderness, or costovertebral angle pain or tenderness. • Urine studies should not be ordered in elderly nursing home residents with nonspecific symptoms to avoid the therapeutic dilemma of whether to prescribe antibiotic therapy for a positive urine culture. • Because of the high NPV of urinary dipstick results in nursing home residents, further urinary tests should not be performed when a negative result for leukocyte esterase and nitrite is present.
ARTICLE INFORMATION
REFERENCES
Author Affiliations: Section of Infectious Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut (Juthani-Mehta); Section of Geriatrics, Department of Internal Medicine, Yale University, New Haven, Connecticut (Datunashvili, Tinetti).
1. Lachs MS, Nachamkin I, Edelstein PH, Goldman J, Feinstein AR, Schwartz JS. Spectrum bias in the evaluation of diagnostic tests: lessons from the rapid dipstick test for urinary tract infection. Ann Intern Med. 1992;117(2):135-140.
Corresponding Author: Manisha Juthani-Mehta, MD, Section of Infectious Diseases, Department of Internal Medicine, Yale University, PO Box 208022, New Haven, CT 06520 ([email protected]). Section Editor: Mary McGrae McDermott, MD, Senior Editor. Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Mehta reports receipt of payment for manuscript preparation from BMJ; payment for development of educational presentations from the University of Cennecticut, Middlesex Hospital, and the American Society of Nephrology; and receipt of travel/ accommodations/meeting expenses unrelated to other listed activities from the Association of Specialty Professors. No other disclosures were reported.
1688
ation of UTI should not have been pursued. If the dipstick analysis was performed and both nitrite and leukocyte esterase results were negative, further evaluation could have been halted.2 In this case, a catheterized specimen was sent for urinalysis and urine culture showing pyuria and bacteriuria, which are nondiagnostic for UTI in this setting. Unnecessary catheterization introduces a risk of infection.
2. Juthani-Mehta M, Tinetti M, Perrelli E, Towle V, Quagliarello V. Role of dipstick testing in the evaluation of urinary tract infection in nursing home residents. Infect Control Hosp Epidemiol. 2007;28 (7):889-891. 3. Devillé WL, Yzermans JC, van Duijn NP, Bezemer PD, van der Windt DA, Bouter LM. The urine dipstick test useful to rule out infections: a meta-analysis of the accuracy. BMC Urol. 2004;4:4. 4. Ducharme J, Neilson S, Ginn JL. Can urine cultures and reagent test strips be used to diagnose urinary tract infection in elderly emergency department patients without focal urinary symptoms? CJEM. 2007;9(2):87-92. 5. Mody L, Juthani-Mehta M. Urinary tract infections in older women: a clinical review. JAMA. 2014;311(8):844-854.
6. Lammers RL, Gibson S, Kovacs D, Sears W, Strachan G. Comparison of test characteristics of urine dipstick and urinalysis at various test cutoff points. Ann Emerg Med. 2001;38(5):505-512. 7. Juthani-Mehta M, Quagliarello V, Perrelli E, Towle V, Van Ness PH, Tinetti M. Clinical features to identify urinary tract infection in nursing home residents: a cohort study. J Am Geriatr Soc. 2009;57 (6):963-970. 8. Centers for Medicare & Medicaid Services. Clinical laboratory fee schedule. http://www.cms .gov/Medicare/Medicare-Fee-for-Service-Payment /ClinicalLabFeeSched/index.html. Updated April 11, 2013. Accessed June 26, 2014. 9. Sundvall PD, Ulleryd P, Gunnarsson RK. Urine culture doubtful in determining etiology of diffuse symptoms among elderly individuals: a cross-sectional study of 32 nursing homes. BMC Fam Pract. 2011;12:36. 10. Nicolle LE. Symptomatic urinary tract infection in nursing home residents. J Am Geriatr Soc. 2009;57(6):1113-1114.
JAMA October 22/29, 2014 Volume 312, Number 16
Copyright 2014 American Medical Association. All rights reserved.
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JAMA Diagnostic Test Interpretation
Tests for Urinary Tract Infection in Nursing Home Residents Manisha Juthani-Mehta, MD; Ann Datunashvili, MD; Mary Tinetti, MD
A nursing home resident in her 80s has a history of falls, cognitive impairment, and incontinence. In the past 2 years, she was thought to have a urinary tract infection (UTI) on 8 occasions and received antibiotic therapy 6 times. Symptoms that triggered an evaluation for UTI included increased confusion, urinary frequency, cloudy urine, lethargy, hallucinations, and falls. On this occasion, the family reports that she “doesn’t look right,” but the nursing staff states she is not confused. The patient reports no dysuria or abdominal pain but does chronically complain of voiding frequently. She is afebrile with no abdominal, suprapubic, or flank tenderness, but her urine has a foul odor. A catheterized urine specimen is obtained and results of urinalysis are reported (Table). The urine culture reveals more than 100 000 colony-forming units (CFUs) per milliliter of Escherichia coli, which is sensitive to all antibiotics except ampicillin. Table. Case Patient’s Urinalysis Test Results Result
Reference Standards/Ranges
Color
Yellow, hazy
Yellow
Specific gravity
1.005
1.005-1.030
pH
7
5.5-7.5
Blood
1+
Negative
Protein
Negative
Negative
Nitrite
1+
Negative
Leukocyte esterase
3+
Negative
Bacteria
3+
None-few/hpf
White blood cells
40-100/hpf
0-5/hpf
Red blood cells
2/hpf
0-5/hpf
Epithelial cells
0-5/lpf
None-few/lpf
HOW DO YOU INTERPRET THESE TEST RESULTS?
A. The patient has asymptomatic pyuria and bacteriuria. B. The patient has a UTI because of chronic incontinence and a positive urine culture. C. A positive urinalysis and urine culture are always a UTI. D. Since the patient has a history of recurrent UTIs, these urine test results indicate that she has another UTI.
Abbreviations: hpf, high-power field; lpf, low-power field.
Answer A. The patient has asymptomatic pyuria and bacteriuria.
Test Characteristics The evaluation of suspected UTI involves identifying specific signs or symptoms associated with symptomatic UTI and appropriate interpretation of 3 potential tests: bedside urinary dipstick, urinalysis, and urine culture. The dipstick has different test characterisRelated article page 1677 tics depending on the population studied and the patient’s clinical presentation.1 In adults Quiz at jama.com aged 65 years or older, the sensitivity of the dipstick (positive to leukocyte esterase, nitrite, or both) for urine culture with more than 100 000 CFU/mL ranges from 65%to100%;specificity,20%to77%;positivepredictivevalue(PPV), 31% to 45%; negative predictive value (NPV), 90% to 100%; positive likelihood ratio (LR+), 1.25 to 2.8; and negative likelihood ratio (LR−), 0 to 0.46.2-4 When leukocyte esterase, nitrite, or both are positive at any level, dipstick results are not helpful in the evaluation of UTI because of low PPV. Because the NPV of the dipstick is high in nursing home residents, a negative test result for leukocyte esterase and nitrite suggests that further evaluation for UTI is unnecessary.
On urinalysis, more than 10 white blood cells per high-power field (WBC/hpf) is an accepted threshold for pyuria required for UTI diagnosis in an older adult. 5 The sensitivity of more than 10 WBC/hpf for more than 100 000 CFU/mL is 78%; specificity, 63%; PPV, 64%; NPV, 74%; LR+, 2.11; and LR−, 0.35. 6 Pyuria should only be used to confirm a clinical diagnosis of UTI. Test characteristics of the urine culture are not available because urine culture results (ⱖ100 000 CFU/mL) are part of the criterion standard and accepted definition of UTI in older adults.5,7 Based on the Medicare fee schedule, costs are as follows: urinary dipstick, $4.32; urinalysis, $2.96 to $4.15; basic urine culture, $11.01; bacterial identification $7.06 to $27.36; and antibiotic susceptibilities $6.48 to $11.80.8
Application of Test Result to This Patient The urinalysis and urine culture results are positive in this patient. However, asymptomatic pyuria (45%) and asymptomatic bacteriuria (25%-50%) are highly prevalent in female nursing home residents and are not sufficient to make the diagnosis of UTI.9 The clinical criteria for symptomatic UTI in older women include 2 or more of the following signs and symptoms: fever, worsened urinary urgency or frequency, acute dysuria, suprapubic tenderness, or costovertebral angle pain or tenderness.5 Laboratory tests confirming
jama.com
JAMA October 22/29, 2014 Volume 312, Number 16
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ by a Georgian Court University User on 05/11/2015
1687
Clinical Review & Education JAMA Diagnostic Test Interpretation
the diagnosis include bacteriuria (ⱖ100 000 CFU/mL) and pyuria (ⱖ10 WBC/hpf). With none of the clinical criteria for symptomatic UTI present, this patient has asymptomatic bacteriuria and pyuria. Three clinical features, acute dysuria, change in character of urine, and change in mental status, were associated with bacteriuria plus pyuria in elderly nursing home residents7; however, both change in mental status and change in character of urine can occur in bacteriuric and nonbacteriuric nursing home residents.10 Bacteriuria was present in 39% of female nursing home residents with restlessness, 41% with fatigue, 45% with confusion, 39% with aggressiveness, 60% with “not being herself,” 42% with urgency, 42% with dysuria, and 50% with fever.9 As in this patient, it should be anticipated that if a urinalysis and urine culture are performed, pyuria and bacteriuria would be present. Given the clinical presentation of this patient, these results represent asymptomatic pyuria and bacteriuria, which do not require antibiotic therapy.
What Are Alternative Diagnostic Testing Approaches? Since the patient only had change in character of urine, a preferable approach would be to initiate hydration first to determine if foul-smelling urine resolves. If it persists and change in mental status develops, a thorough evaluation of other potential etiologies should be pursued first (eg, discontinuation of diuretics or adjustment of medications affecting mentation). If both symptoms persist, performing a dipstick test is warranted.5 In this patient, evalu-
Patient Outcome This patient was treated with cefuroxime for 7 days. It was unclear whether treatment produced any improvement in clinical status.
Clinical Bottom Line: • Clinical criteria for symptomatic UTI include 2 or more of the following signs and symptoms: fever, worsened urinary urgency or frequency, acute dysuria, suprapubic tenderness, or costovertebral angle pain or tenderness. • Urine studies should not be ordered in elderly nursing home residents with nonspecific symptoms to avoid the therapeutic dilemma of whether to prescribe antibiotic therapy for a positive urine culture. • Because of the high NPV of urinary dipstick results in nursing home residents, further urinary tests should not be performed when a negative result for leukocyte esterase and nitrite is present.
ARTICLE INFORMATION
REFERENCES
Author Affiliations: Section of Infectious Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut (Juthani-Mehta); Section of Geriatrics, Department of Internal Medicine, Yale University, New Haven, Connecticut (Datunashvili, Tinetti).
1. Lachs MS, Nachamkin I, Edelstein PH, Goldman J, Feinstein AR, Schwartz JS. Spectrum bias in the evaluation of diagnostic tests: lessons from the rapid dipstick test for urinary tract infection. Ann Intern Med. 1992;117(2):135-140.
Corresponding Author: Manisha Juthani-Mehta, MD, Section of Infectious Diseases, Department of Internal Medicine, Yale University, PO Box 208022, New Haven, CT 06520 ([email protected]). Section Editor: Mary McGrae McDermott, MD, Senior Editor. Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Mehta reports receipt of payment for manuscript preparation from BMJ; payment for development of educational presentations from the University of Cennecticut, Middlesex Hospital, and the American Society of Nephrology; and receipt of travel/ accommodations/meeting expenses unrelated to other listed activities from the Association of Specialty Professors. No other disclosures were reported.
1688
ation of UTI should not have been pursued. If the dipstick analysis was performed and both nitrite and leukocyte esterase results were negative, further evaluation could have been halted.2 In this case, a catheterized specimen was sent for urinalysis and urine culture showing pyuria and bacteriuria, which are nondiagnostic for UTI in this setting. Unnecessary catheterization introduces a risk of infection.
2. Juthani-Mehta M, Tinetti M, Perrelli E, Towle V, Quagliarello V. Role of dipstick testing in the evaluation of urinary tract infection in nursing home residents. Infect Control Hosp Epidemiol. 2007;28 (7):889-891. 3. Devillé WL, Yzermans JC, van Duijn NP, Bezemer PD, van der Windt DA, Bouter LM. The urine dipstick test useful to rule out infections: a meta-analysis of the accuracy. BMC Urol. 2004;4:4. 4. Ducharme J, Neilson S, Ginn JL. Can urine cultures and reagent test strips be used to diagnose urinary tract infection in elderly emergency department patients without focal urinary symptoms? CJEM. 2007;9(2):87-92. 5. Mody L, Juthani-Mehta M. Urinary tract infections in older women: a clinical review. JAMA. 2014;311(8):844-854.
6. Lammers RL, Gibson S, Kovacs D, Sears W, Strachan G. Comparison of test characteristics of urine dipstick and urinalysis at various test cutoff points. Ann Emerg Med. 2001;38(5):505-512. 7. Juthani-Mehta M, Quagliarello V, Perrelli E, Towle V, Van Ness PH, Tinetti M. Clinical features to identify urinary tract infection in nursing home residents: a cohort study. J Am Geriatr Soc. 2009;57 (6):963-970. 8. Centers for Medicare & Medicaid Services. Clinical laboratory fee schedule. http://www.cms .gov/Medicare/Medicare-Fee-for-Service-Payment /ClinicalLabFeeSched/index.html. Updated April 11, 2013. Accessed June 26, 2014. 9. Sundvall PD, Ulleryd P, Gunnarsson RK. Urine culture doubtful in determining etiology of diffuse symptoms among elderly individuals: a cross-sectional study of 32 nursing homes. BMC Fam Pract. 2011;12:36. 10. Nicolle LE. Symptomatic urinary tract infection in nursing home residents. J Am Geriatr Soc. 2009;57(6):1113-1114.
JAMA October 22/29, 2014 Volume 312, Number 16
Copyright 2014 American Medical Association. All rights reserved.
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