Procalcitonin test may stem antibiotic overuse

While the symptoms of many lung infections are the same, the major cause of these illnesses is viral rather than bacterial. However, up to 75% of patients are treated with antibiotics. This unnecessary use of antibiotics - prescribed for lung diseases more than any other illnesses - increases medical costs and can lead to more drug-resistant bacteria.

PCT, produced by the body primarily in response to bacterial infections, can help doctors distinguish bacterial from non-bacterial causes of infection as well as the severity of infections. The diagnostic use of PCT is becoming more widespread since hospitals are increasingly able to quickly test PCT levels.

Writing in the September 9 issue of the Journal of the American Medical Association, Swiss researchers reported on the use of an algorithm that encourages or discourages antibiotic use in patients with lower respiratory tract infections based on the patients' PCT levels. Previously reported studies have examined similar algorithms and compared PCT-directed antibiotic therapy to treatment based on usual care practices. While these studies have shown directed therapy to be beneficial, the Swiss study is the first to examine their use in a multiple hospital setting. They studied 1,359 patients who presented to the Emergency Departments of six Swiss tertiary care hospitals. They used a PCT test that provides results within 30 minutes, allowing it to be used in real-time decision making.

Patients treated according to the PCT algorithm received less antibiotics and had fewer complications. The unnecessary use of antibiotics was stopped earlier in those patients who were being monitored with PCT than in those who were not monitored and this represented a significant difference between the two groups.

Commentary urges caution
An accompanying editorial says that the indiscriminate use of antibiotics to treat lower respiratory tract infections "fails to consider the basic questions of who would benefit (or be harmed) from antibiotic therapy, and if treated, what is the optimal duration." It accepts that the Swiss research does show PCT can help safely reduce antibiotic in these situations. The commentators, however, rightly maintain that the ultimate value of the use of clinical decision rules and algorithms such as the Swiss researchers' "is a function of diagnostic accuracy, effectiveness in changing clinician behavior, safety for patients, and both individual and societal cost." They are also dependent on physician compliance with treatment recommendations, which in the Swiss study were "commendably high."

The commentary concludes that although this PCT-guided decision rule holds promise for the management of patients with lung infections, these issues must be carefully considered before broadly translating this research into clinical practice.

Donald M. Yealy and Michael J. Fine. Measurement of Serum Procalcitonin - A Step Closer to Tailored Care for Respiratory Infections? Journal of the American Medical Association. Available online at http://jama.ama-assn.org/cgi/content/full/302/10/1115 through http://jama.ama-assn.org. Published September 9, 2009. Accessed October 2009.

John A. Marx. Procalcitonin Algorithm Reduces Antibiotic Use for Lower Respiratory Tract Infections. Journal Watch Emergency Medicine. Available online at http://emergency-medicine.jwatch.org/cgi/content/full/2009/1002/1?q=etoc_jwid# through http://emergency-medicine.jwatch.org. Published October 2, 2009. Accessed October 2009.

Elizabeth Lopatto. Blood Test May Prevent Overuse of Antibiotics, Study Shows. Bloomberg News. Available online at http://www.bloomberg.com/apps/news?pid=20601081&sid=anpaBua3k_04 through http://www.bloomberg.com. Published September 8, 2009. Accessed October 18, 2009.