Measuring hormone procalcitonin cuts antibiotic use in half in pneumonia patients

May 25 2005

Measuring a hormone in the blood can help doctors greatly reduce the number of days pneumonia patients have to take antibiotics to cure their infection, according to a study to be presented at the American Thoracic Society International Conference.

In the study, pneumonia patients whose level of the hormone procalcitonin was measured during the course of their illness took antibiotics an average of 6 days, compared with 12 days for patients whose procalcitonin levels were not measured. Fifteen percent of patients whose hormone levels were measured did not have to take antibiotics at all, said study co-author Michael Tamm, M.D., Chief of Pulmonary Medicine and Pulmonary Cell Research at University Hospital in Basel, Switzerland.

"Because of concerns about antibiotic resistance, as well as the cost of antibiotics, it's always better to give fewer antibiotics," Prof. Tamm said.

Many cases of community-acquired pneumonia are caused by bacteria, which require treatment with antibiotics, but some cases are viral, which get better without antibiotics. But doctors don't like to delay treatment in order to wait for lab results to tell them whether a patient's pneumonia is bacterial or viral, so they start all patients on antibiotics, Dr. Tamm said. "Once the treatment is started, it is usually continued for 10 to 14 days, because nobody knows when you can stop without a risk for the patient," he said.

Because levels of procalcitonin have been found to be elevated in patients with bacterial infection but not viral infection or other inflammatory diseases, Dr. Tamm and colleagues decided to study whether measuring levels of the hormone could eliminate or reduce antibiotic use in patients with bacterial pneumonia. Results of the blood test that measures procalcitonin levels can be obtained in only one hour, he said.

They studied more than 300 patients with community-acquired pneumonia (pneumonia that is not caught while a patient is in the hospital), and randomly divided them into two groups. Once group was given the standard antibiotic treatment, while the other was first tested for procalcitonin levels. Fifteen percent of those patients had very low procalcitonin levels, and were presumed to have viral pneumonia; they were not given antibiotics. The remaining 85% had high levels and were started on antibiotics. The researchers measured their procalcitonin levels four, six and eight days later, and discontinued their antibiotics if their levels were low.

Patients in the procalcitonin group who started on antibiotic treatment were able to stop after an average of six days. Their course of illness was similar to those patients who received a full course of antibiotics, in terms of their recovery and number of days spent in the hospital. "We showed we were able to cut the number of days patients were on antibiotics in half, without compromising their outcome," Dr. Tamm said.

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