Point-of-Care PCR Tests Better Diagnosis, Rx for Kids’ Sore Throats

Given we are still in the midst of cold and flu season, a new study highlights the benefit of point-of-care (POC) polymerase chain reaction (PCR) testing among pediatric patients presenting to the doctor’s office with sore throats. Under real-world conditions, rapid antigen detection tests (RADTs) and culture were less accurate than in the published literature and led to increased rates of inappropriate antibiotic use, compared to POC PCR, according to a study published Jan. 16 in BMC Pediatrics.

Current clinical guidelines encourage the use of antibiotics only for confirmed cases of group A Streptococcus (GAS), however some studies suggest that antibiotics may be prescribed in as many as 60 percent of patient visits for sore throat. The growing threat of antibiotic resistance is leading to increasing urgency to find rapid, onsite diagnosis of the pathogenic source of respiratory-related infections.

While RADTs offer the benefit of efficiency, the overall sensitivity of the test is low. When combined with culture, the results are highly accurate, but the two-step testing strategy is time and labor intensive, delaying results by up to three days. More recently approved POC PCR tests have reported sensitivity closer to that of cultures, but with the added benefit of more rapid turnaround times.

The researchers compared the sensitivity and specificity of the recommended two-step RADT plus confirmatory culture testing strategy versus the Roche cobas Liat Strep A POC PCR test for detection of GAS in 255 pediatric patients (aged 3 to 18 years) with pharyngitis. Throat swab specimens were obtained from patients seen in a large, pediatric, outpatient clinic in the fall/winter of 2016-2017. The RADT or POC PCR result was provided to clinicians on alternating weeks to compare the impact on antibiotic use.

The researchers found that 43.1 percent of samples were positive for GAS. Sensitivity for POC PCR was 95.5 percent versus 85.5 percent for RADT and71.8 percent for culture. Specificities were 99.3 percent, 93.7 percent, and 100 percent, respectively. Culture results took a median of two days. POC PCR results took five to 10 minutes longer RADT. Compared with RADT plus culture, POC PCR resulted in significantly greater appropriate antibiotic use (97.1 percent versus 87.5 percent).

“POC PCR can provide highly accurate results for patients at the time of the office visit, eliminating the need for follow-up confirmatory testing of negative results and for empiric treatment,” write the authors led by Arundhati Rao, from the Scott and White Medical Center–Temple in Texas. “Providers in this busy pediatric clinic believed that the increased wait time and decreased room availability were offset by more appropriate antibiotic use, the potential for fewer missed days of school/work for patients and their parents, and less staff and provider time and resources while awaiting confirmatory culture results.”

Takeaway: POC PCR testing appears to speed accurate diagnosis of Strep A-related sore throats in kids and drive more appropriate antibiotic use.