Background: Rapid antigen detection tests (RADT) are commonly used to guide appropriate antibiotic treatment of group A beta-hemolytic streptococcal (GABHS) pharyngitis. In adults, there is controversy about the need for routine backup testing of negative RADT.
Objective: Estimate the costs and benefits in adults of routine backup testing by DNA Gen-probe of negative RADT (Acceava).
Design: Observational follow-up study.
Participants: All patients aged 18 years and older visiting a Cleveland Clinic generalist physician in 2009 and 2010 with a visit diagnosis of acute pharyngitis (ICD codes 462, 034.0).
Main measures: The patients were identified using the Cleveland Clinic Epic Clarity database. We determined the proportion of false negative RADT, antibiotic prescription patterns and rate of serious suppurative complications within 30 days of the office visit.
Key results: Of 25,130 patients with acute pharyngitis, 19% had no testing and 81% were tested. Of the 15,555 patients that had a negative RADT and follow-up DNA probe, 6% had a positive DNA probe. Of the 953 patients who had a negative RADT and a positive DNA strep probe, 48% received an antibiotic prescription at the time of the visit and 51% received an antibiotic prescription after an average of 2.3 days. Only one patient with a negative RADT and no follow-up DNA probe developed a peritonsillar abscess. Overall, of the 15,555 DNA probes performed, management was altered in only 3% of the patients at a total cost of $1,757,715. Fifty-six percent received an antibiotic while only 19.5% had a confirmed strep throat diagnosis.
Conclusions: The false negative rate of Acceava RADT for the diagnosis of GABHS pharyngitis was 6%. We question the benefit of routine DNA probe backup testing in adults because of its substantial cost, an average delay in antibiotic prescribing of over 2 days, and because suppurative complications are very uncommon. We found a high rate of inappropriate antibiotic prescribing.