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CC Jan 2016 Influenza diagnosis

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echoecho's version from 2016-01-01 17:32

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Question Answer
The CDC has offered a guidelines of questions to ask a patient when trying to differentiate a patient presenting with symptoms typical of influenza infection (sudden onset of fever, myalgia, chills and fatigue) versus other viral and bacterial infections. What is the website for these questions?www.cdc.gov/flu/professionals/diagnosis/labrolesprocedures.htm
QUESTION 1: Does the patient have clinical signs or symptoms that are consistent with influenza? If the answer is NO, what is recomemnded. If the answer is YES, proceed to Question 2?if the answer is NO, influenza testing is not recommended
QUESTION 2: Will the results of influenza testing either (a) change clinical care for the patient (especially for hospitalized patients and those with high-risk conditions, such as pregnancy, chronic lung disease, heart disease, renal disease, metabolic disease, hematologic disease, neurologic disease, morbid obesity or immunosuppression OR (b) influence clinical practice for other patients (including decisions on changing infectious control practices when patients are hospitalizaed or in a nursing home? If the answer is NO, what is recommended. If the answer is YES, what is recommended?1) if the answer is NO, influenza testing is not recommended 2) if the answer is YES, influenza testing should be considered
*** If testing is ordered, the CDC recomemnds an approach based on what?whether or not influenza viruses are circulating in the community
*** What is the plan if influenza viruses ARE circulating in the community?1) obtain a rapid influenza diagnostic test (RIDT) 2) if the RIDT is positive for influenza A, B or A/B, the patient should be considered to have influenza, receive antiviral therapy if clinically indicated and additional testing should be considered to confirm the RIDT results and identify subtypes 3) if the RIDT is negative, influenza CANNOT be excluded and providers should use patient hx, clinical s/s and information from the community to determine whether antivifral therapy is indicated
*** What is the plan if influenza viruses ARE NOT circulating in the community?1) obtain a rapid influenza diagnostic test (RIDT) and if the test is positive, a false-positive test CANNOT be excluded. 2) Providers should use the pt hx, clinical s/s and information from the commjunity to determine whether antiviral therapy is indicated 3) additional viral testing is recommended, such as polymerase chain reaction (PCR) testing and if the test is negative, influenza infection is unlikely
List the 4 comments that the CDC makes about rapid influenza diagnostic testing (RIDT)?1) RIDT should be performed within 48-72 hours of illness onset to improve diagnostic yield 2) physicians should be familiar with the RIDT they are planning to use, because different RIDTs are collected from different sites (nasopharyngeal, nasal, throat swab) using diferrent methods. Some RIDTs test for influenza A, some for influenza B and some for both (www.cdc.gov/flu/pdf/professionals/diagnostic/table-2-rapid-diagnostic.pdf) 3) some RIDTs use the entire collected specimen, while others allow some of the sample to be sent for PCR or culture 4) in general, compared to the gold standard test (PCR or viral cultures), RIDTs have low sensitivity but high specificity
*** PCR identifies what but does not indicate what?1) identifies the presence of viral RNA 2) does not indicate infectivity or activity
Regarding PCR testing, list characteristics of this test?1) as with RIDTs, some PCR tests have the ability to detect influenza A, some influenza B, and some both 2) the results typically take 3-8 hours to be reported, so they are generally NOT useful in the ambulatory or emergency department setting 3) hosptalied patients with lower respiratory tract infection who meet criteria for testing should have upper respiratory tract testing for influenza 4) if PCR testing is negative and a positive test would change management, lower respiratory tract testing can be considered
Compare RIDT to PCR testing?Compared to RIDT, PCR testing is more sensitive and results in lower rates of false positive and false negatives
PCR testing should be done when?asap (w/in 48-72 hours of onset of s/s)
Should treatment, if indicated, be withheld while results of PCR are pending?no, pt should be treated if indicated
*** SUMMARY = Rapid influenza diagnostic tests (RIDT) may test for what? Interpretiona of a positive test depends on what?1) influenza A, B or both A & B 2) on whether influenza is circulating in the community
*** SUMMARY = RIDT should be performed within ____ to ____ hours of illness onset to improve diagnostic yield?48; 72
*** SUMMARY = What testing is more sensitive than RIDT?PCR (polymerase chain reaction)
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