Rapid Flu Tests Effective for Ruling In (But Not Out) Diagnosis
(HealthDay News) – Rapid influenza tests are useful for diagnosing influenza; and oral oseltamivir and inhaled zanamivir may be beneficial for the treatment of influenza, according to two reviews published online Feb. 27 in the Annals of Internal Medicine.
Caroline Chartrand, MD, from CHU Sainte-Justine in Montreal, and colleagues reviewed 159 studies that evaluated 26 rapid influenza diagnostic tests to examine their diagnostic accuracy. They found that the pooled sensitivity was 62.3% and the pooled specificity was 98.2%. The positive likelihood ratio was 34.5 and the negative likelihood ratio was 0.38. Sensitivity estimates were very heterogeneous, which was partially accounted for by lower sensitivity in adults than children (53.9% vs. 66.6%) and increased sensitivity for influenza A than influenza B (64.6% vs. 52.2%). The authors concluded that rapid tests were therefore appropriate for ruling in, but not ruling out, the diagnosis of influenza.
Jonathan Hsu, from McMaster University in Hamilton, Canada, reviewed 74 studies that examined the efficacy of antiviral treatment for influenza. The researchers found that, compared with no treatment, oral oseltamivir was associated with reduced mortality in high-risk populations (odds ratio [OR], 0.23), hospitalization (OR, 0.75), and symptom duration (33 hours). Compared with no treatment, inhaled zanamivir was associated with reduced symptom duration (23 hours) and fewer hospitalizations (OR, 0.66) but more complications. There were no important differences seen in key outcomes in a direct comparison of oral oseltamivir and inhaled zanamivir.
"Oral oseltamivir and inhaled zanamivir may provide a net benefit over no treatment for influenza," Hsu and colleagues conclude.