Urinary Tract Infection: Likelihood Ratios

Introduction: An uncomplicated, or lower, UTI is also known as cystitis. The principal symptoms are dysuria, frequency, urgency; hematuria can also be present.

Non-diagnostic historical findings (from Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379) include:

history of backache, fever, feeling unwell, abdominal pain, prior duration, daytime or night-time frequency (number of times), renal angle tenderness, lower abdominal tenderness, previous history of UTI.

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Differential Diagnoses include: Appendicitis, Pyelonephritis

Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
Women with suspected UTI	62%	Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379
	50%
	45%
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The likelihood ratios of findings for Urinary Tract Infection are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Negative Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] Dipstick Leukocyte Esterase	+ 0 -	1.8	0.3
Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379
[ + ] Dipstick Blood	+ 0 -	1.6	0.5
Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379

Good Positive Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] Dipstick Nitrite	+ 0 -	3.1	0.8
Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379
[ + ] Urine Malodor	+ 0 -	2.4	0.8
Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379
[ + ] Cloudy Urine	+ 0 -	2.2	0.7
Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379

Good Positive and Negative Likelihood Ratios
Finding	Result	+LR	-LR
[ + ] Self-Diagnosis	+ 0 -	4	0
Study: JAMA. 2002;287:2701-2710. http://jama.ama-assn.org/cgi/content/full/287/20/2701
[ + ] Urine Culture	+ 0 -	6.3	0.1
>10^2 CFU/ml of E coli. Population: symptomatic women. Study: N Engl J Med 1982 Aug 19;307(8):463-8. PMID 7099208
[ + ] Pyuria	+ 0 -	3.3	0.1
i.e. microscopic leukocytes Study: N Engl J Med. 2003 Jul 17;349(3):259-66. PMID 12867610
[ + ] Dipstick Leukocyte Esterase or Nitrite	+ 0 -	4.2	0.3
Study: N Engl J Med. 2003 Jul 17;349(3):259-66. PMID 12867610
[ + ] Dipstick Nitrite or Dipstick Blood and Leukocyte Esterase	+ 0 -	2.6	0.3
Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379
[ + ] Bacteriuria	+ 0 -	4.7	0.4
i.e. microscopically visible bacteria in urine (sensitivity depends a lot on the cutoff number of bacteria) Study: N Engl J Med. 2003 Jul 17;349(3):259-66. PMID 12867610

Poorly Diagnostic Findings
Finding	Result	+LR	-LR
[ + ] Hematuria	+ 0 -	1.9	0.9
moderately severe Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379
[ + ] Costovertebral Angle Tenderness	+ 0 -	1.8	0.9
Study: JAMA. 2002;287:2701-2710. http://jama.ama-assn.org/cgi/content/full/287/20/2701
[ + ] Dipstick Protein	+ 0 -	1.5	0.8
Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379
[ + ] Nocturia	+ 0 -	1.5	0.7
moderately severe (population is women with suspected UTI) Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379
[ + ] Urinary Urgency	+ 0 -	1.2	0.8
moderately severe Study: Br J Gen Pract. 2006 Aug;56(529):606-12. PMID 16882379
[ + ] Flank Pain	+ 0 -	1.1	0.9
Study: JAMA. 2002;287:2701-2710. http://jama.ama-assn.org/cgi/content/full/287/20/2701