A simple test reduces antibiotic prescription

General practitioners too often prescribe antibiotics for acute respiratory tract infections. One of the reasons for an inappropriate use of antibiotics is the difficulty to distinguish between a bacterial pneumonia, which requires antibiotics, and non-bacterial infections, which are self-resolving. In order to improve the diagnosis of respiratory tract infections, a team of researchers of CHUV, led by Noémie Boillat Blanco, developed a procedure that combines ultrasound examination of the lungs with a procalcitonin test helping in differentiating between bacterial and viral infections. However, since each method on its own produces too many unreliable diagnoses, they combined their results sequentially with an algorithm to increase diagnostic precision.

Practical study with general practitioners: decrease in antibiotic prescription

To evaluate this novel diagnostic approach, the researchers conducted a study, in which sixty general practitioners applied it in practice over several months. They then compared the antibiotic prescription of physicians using their approach with doctors not using the approach. The study showed that the use of a rapid procalcitonin test reduced antibiotic prescriptions by one third compared to usual management: Antibiotics were prescribed in 40% of patients with symptoms while the number was above 70% in patients having a usual management. However, Boillat Blanco and her team did not see an additional reduction in prescribing with the use of lung ultrasound. The lack of added value of ultrasound use is related to the fact that this test was rarely performed, as it was only recommended in patients with an elevated procalcitonin (suggesting the presence of a bacterial infection).

Equal therapy successes

This decrease in antibiotic prescription by physicians using a procalcitonin test did not have a negative impact on patient recovery. On the other hand, the intervention decreased the use of chest X-rays compared to usual management (ca. 20% versus ca. 50%). The estimated cost of using procalcitonin per 1% reduction in antibiotic prescribing was 2 CHF. The researchers conclude that the rapid procalcitonin test can reduce antibiotic prescriptions in patients with suspected pneumonia in primary care without affecting their recovery, and that the use of this test is cost-effective. Following these results, the Swiss Society for Infectious Diseases included procalcitonin guidance as an alternative to chest X-ray in Swiss guidelines for the management of pneumonia. However, the routine use of this test by general practitioners depends on its coverage by the health insurances. If this can be secured, it could be widely deployed very rapidly.

October 2022

Procalcitonin and lung ultrasonography point-of-care testing to decide on antibiotic prescription in patients with lower respiratory tract infection at primary care level: cluster randomised trial