Rapid H1N1 Diagnosis

Friday, October 29, 2010 // Uncategorized

8/9/2009 2:06:09 PM

In other times witchdoctors cast bones to make the diagnosis on their patietns.  Not being trained in the interpretation of bones thrown from a bag, I rely on more current diagnostic tests.  I have yet to be impressed by the accuracy of rapid flu tests for seasonal or novel flu viruses.  I often hear people say that they were diagnosed with these tests in an urgent care clinic.  Here is a summary of a recent study.  Not very impressive.  I think I’ll rely on clinical symptoms.

H1N1 Update: Rapid Diagnostic Tests Have Low Overall Sensitivity for Novel Influenza A Virus
Preliminary data from the CDC suggest that rapid influenza diagnostic tests have a low overall sensitivity for novel influenza A (H1N1), MMWR reports.
Sixty-five respiratory specimens that tested positive for novel influenza A (H1N1) or seasonal influenza A (H1N1 or H3N2) by reverse-transcription polymerase chain reaction were tested again using three rapid tests.
Among the findings:
Overall sensitivity for novel influenza A ranged from 40% to 69%.
For nine specimens with high viral titers of novel influenza A, sensitivity ranged from 89% to 100%.
The tests were generally more sensitive for seasonal flu (range, 60% to 83%) than for novel influenza A.

An editorial note concludes that, for now, all results from rapid tests in suspected H1N1 cases “should be interpreted in the context of circulating influenza virus strains in the patient’s community, level of clinical suspicion, severity of illness, and risk for complications.”


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