Rapid Influenza Diagnostic Tests- Not So Accurate

Source: CDC.gov

So the flu season is nearly over in the Northern hemisphere. Regardless, this is still of relevance.

If one has a bad cold, and suspects influenza, I cannot argue with seeking medical advice. However, if one is subjected to a rapid influenza diagnostic test (RIDTs) on a nasopharyngeal sample, the result may not be accurate. 

This review and meta-anlaysis of 159 studies on RIDTs is revealing.  The pooled sensitivity and specificity for RIDTs were 62.3% (95% CI, 57.9% to 66.6%) and 98.2% (CI, 97.5% to 98.7%), respectively. In other words, a positive RIDT rules in influenza but a negative RIDT does not exclude the diagnosis. 

RIDTs are of variable utility. That is why we no longer use them in my hospital. The gold standard for influenza detection is viral culture or PCR, both are time consuming, taking at least 24 hours for a result.

The treatment of influenza, at least initially, remains largely a decision based on local influenza disease activity, patient risk factors and physician clinical acumen.