Alere i System
Up to 30 % of children and 5- 15% of adults presenting with symptoms of sore throat are diagnosed with Group A Streptococcus. Identifying strep at the point of care expedites resolution of symptoms, limits spread in families and in schools, and prevents development of suppurative complications such as peritonsillar abscess. Unfortunately, lateral flow point of care assays have limited sensitivity (86% in a recent meta-analysis), compared to throat culture, and thus some patients with strep infections are not diagnosed expeditiously! In the case of influenza, lateral flow assays have sensitivities of 64.6% for Influenza A and 52.2% for influenza B compared compared to reference lab tests, so many patients with influenza who might benefit from antiviral treatment are not identified.
Last year the Alere i System was introduced. This is disruptive technology is that it brings reference lab diagnostic accuracy to the medical office. In the case of strep pharyngitis, sensitivity and specificity exceeds 95% in a test that takes less than 10 minutes to complete. In the case of influenza A and B, sensitivity and specificity exceeds 99%/98% in a 15 minute assay.
Unlike traditional PCR tests which use repeated heating and cooling cycles to disrupt the nucleic acid of the target organism, the Alere i system uses isothermal technology – using enzymes to disrupt nucleic acids. Therefore it produces results in minutes rather than hours.
I have written several previous articles about rapid strep and influenza assays. In the case of strep the diagnostic accuracy of tabletop PCR testing makes it unnecessary to send backup throat cultures. The Alere i assays are a bit more expensive for practices and patients, but are reimbursed at higher rates. In time molecular assays will evolve to be “standard of care” and the prices will come down.