Infective Endocarditis: Likelihood Ratios

Introduction: Endocarditis refers to bacterial infection of the heart valves, manifested by vegetations of bacteria growing on the valves. Endocarditis will cause bacteremia and septic emboli; it may also destroy the valve involved.

Nowadays, the Duke Criteria are the clinical 'gold standard' diagnostic test (though obviously, pathology is the true gold standard) - but note that the Duke criteria are certainly not completely sensitive and may be nonspecific, depending on the case series (see below). The two papers cited below disagree about whether 'possible' endocarditis by Duke criteria should be considered as truly positive or not.

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Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
Patients given TTE with suspicion of endocarditis	4%	Q J Med 2006; 99:23–31. PMID 16330508
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The likelihood ratios of findings for Infective Endocarditis are listed below. See the left navigation bar to change the display.

Good Positive and Negative Likelihood Ratios

Finding	+LR	-LR	Comments, Study
Duke Criteria Duplicate	8.3	0	Definite or possible endocarditis by Duke criteria. Possible endocarditis: does not meet criteria for definite (see other entry) but also does not meet criteria for 'rejected', namely any of: firm alternative diagnosis explaining evidence of infective endocarditis; resolution of infective endocarditis syndrome with antibiotic treatment for 4 or less days; no pathologic evidence of infective endocarditis at surgery or autopsy with antibiotic therapy for 4 or less days. Other study found sens and spec of 96% and 36% ! (http://www.psmid.org.ph/vol26/vol26num4topic5.pdf) Study: Eur Heart J. 1997 Jul;18(7):1149-56. PMID: 9243150
Trans-Esophageal Echocardiography	inf	0.1	vegetation seen on TEE Study: J Am Coll Cardiol 1991 Aug;18(2):391-7. PMID: 1856406
Duke Criteria Duplicate	25.3	0.2	Need: 2 major OR 1 major + 3 minor OR 5 minor Major Criteria: positive blood cx with typical organisms vegetations on echo new murmur serology or culture of Coxiella burnetii Minor Criteria: fever predisposing valvular problem or IV drug use evidence of emboli evidence of immune complex deposition positive blood cultures of non-typical organisms Other study found sens and spec of 86% and 82% (http://www.psmid.org.ph/vol26/vol26num4topic5.pdf) Study: Eur Heart J. 1997 Jul;18(7):1149-56. PMID: 9243150
Blood Cultures	2.6	0.3	35% were S aureus, 35% were Strep viridans. Most false negatives had been treated with antibiotics prior to culture. Study: Q J Med 2006; 99:23–31. PMID 16330508
Von Reyn Criteria	8.6	0.3	Definite, Probable, or Possible (less sens, more spec if disregard 'possible') Definite: direct evidence of infective endocarditis based on histology from surgery or autopsy or on bacteriology (Gram's stain or culture) of valvular vegetation or peripheral embolus Probable: (a) persistently positive blood culture, plus one of: new regurgitant murmur; predisposing heart disease and vascular phenomena (petechiae, splinter haemorrhages, conjunctival haemorrhages, Roth spots, Osler's nodes, Janeway lesions, aseptic meningitis, glomerulonephritis and pulmonary, CNS, coronary or peripheral emboli) . (b) negative or intermittently positive blood cultures plus three of the following: fever; new regurgitant murmur; vascular phenomena Possible: (a) persistently positive blood cultures plus one of the following: predisposing heart disease; vascular phenomena. (b) negative or intermittently positive blood cultures with all three of the following: fever; predisposing heart disease; valvular phenomena, (c) for viridans streptococcal cases only- at least two positive blood cultures without an extra-cardiac source and fever Study: Eur Heart J. 1997 Jul;18(7):1149-56. PMID: 9243150

Good Positive Likelihood Ratio

Trans-Thoracic Echocardiography

0.6

Vegetation seen on TTE. However, sensitivity is ~96% if abnormal valvular function is the criterion, i.e. the sensitivity of an abnormal TTE is virtually as good as TEE (though specificity obviously would be lower in that case).

Study: J Am Coll Cardiol 1991 Aug;18(2):391-7. PMID: 1856406

Am J Cardiol 1996 Jul 1;78(1):101-3. PMID 8712097

Poorly Diagnostic Findings

Osler's Nodes

Sensitivity = 10%

This sensitivity is for any cutaneous manifestation.

These represent an inflammatory response to deposited immune complexes. They are "red-purple, tender, slightly raised cutaneous nodules often with a pale center" most often occurring on the fingers and toes.

Study: Q J Med 2006; 99:23–31. PMID 16330508

Janeway Lesion

Sensitivity = 10%

This sensitivity is for any cutaneous manifestation.

These represent septic microemboli. They are "usually non-tender, haemorrhagic macules or papules, located on the palms or soles, especially thenar and hypothenar eminences".

Study: Q J Med 2006; 99:23–31. PMID 16330508