Editing Infective endocarditis (section)

===Risk===
Among people who do not [[intravenous drug use|use intravenous drugs]] and have a fever in the [[emergency department]], there is a less than 5% chance of occult endocarditis. Mellors in 1987 found no cases of endocarditis nor of staphylococcal bacteremia among 135 febrile patients ''in the emergency room''.<ref name=Mellors/> The upper [[confidence interval]] for 0% of 135 is 5%, so for statistical reasons alone, there is up to a 5% chance of endocarditis among these patients. In contrast, Leibovici found that among 113 non-selected adults ''admitted to the hospital'' because of fever there were two cases (1.8% with 95%CI: 0% to 7%) of endocarditis.<ref name=Leibovici/>

Among people who do use intravenous drugs and have a fever in the emergency department, there is about a 10% to 15% prevalence of endocarditis. This estimate is not substantially changed by whether the doctor believes the patient has a trivial explanation for their fever.<ref name = Marantz/> Weisse found that 13% of 121 patients had endocarditis.<ref name=Weisse/> Marantz also found a prevalence of endocarditis of 13% among such patients in the emergency department with fever.<ref name=Marantz/> Samet found a 6% incidence among 283 such patients, but after excluding patients with initially apparent major illness to explain the fever (including 11 cases of manifest endocarditis), there was a 7% prevalence of endocarditis.<ref name=Samet/> During the [[Opioid epidemic in the United States]], hospitals observed an increase in [[stroke]] associated with infective endocarditis.<ref>{{Cite journal |last1=Salehi Omran |first1=Setareh |last2=Chatterjee |first2=Abhinaba |last3=Chen |first3=Monica L. |last4=Lerario |first4=Michael P. |last5=Merkler |first5=Alexander E. |last6=Kamel |first6=Hooman |date=March 2019 |title=National Trends in Hospitalizations for Stroke Associated With Infective Endocarditis and Opioid Use Between 1993 and 2015 |journal=Stroke |language=en |volume=50 |issue=3 |pages=577–582 |doi=10.1161/STROKEAHA.118.024436 |pmid=30699043 |pmc=6396300 |issn=0039-2499}}</ref>

Among people with staphylococcal bacteremia (SAB), one study found a 29% prevalence of endocarditis in community-acquired SAB versus 5% in nosocomial SAB.<ref name=Kaech>{{cite journal | vauthors = Kaech C, Elzi L, Sendi P, Frei R, Laifer G, Bassetti S, Fluckiger U | title = Course and outcome of Staphylococcus aureus bacteraemia: a retrospective analysis of 308 episodes in a Swiss tertiary-care centre | journal = Clinical Microbiology and Infection | volume = 12 | issue = 4 | pages = 345–52 | date = April 2006 | pmid = 16524411 | doi = 10.1111/j.1469-0691.2005.01359.x | doi-access = free }}</ref> However, only 2% of strains were resistant to methicillin and so these numbers may be low in areas of higher resistance.{{citation needed|date=February 2021}}