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Use of Procalcitonin Levels Helps Avoid Unnecessary Antibiotic Use in Acute Respiratory Infection: Presented at ICAAC

By W. A. Thomasson, PhD

CHICAGO, IL -- September 22, 2003 -- In patients with acute lower-respiratory tract infections, procalcitonin levels can help physicians tell if and when antibiotics are needed, according to a study presented here September 16^th at the 43^rd Interscience Conference on Antibiotic Agents and Chemotherapy.

According to Mirjam Christ-Crain, MD, and colleagues, University of Basel, Switzerland, such infections account for 75% of all antibiotic use, even though most are viral in origin.

In their study, randomization was done according to a weekly schedule. For one week, physicians were asked to prescribe antibiotics using clinical criteria, the second week they were asked to decide on antibiotic use after being informed of each patient's measured procalcitonin level and receiving firm guidelines regarding appropriate antibiotic usage. Antibiotics were recommended only if a patient's procalcitonin level was higher than 0.25 ng/mL. In patients with levels ranging between 0.1 and 0.25 ng/mL, antibiotics might be used on strong clinical indications.

Over the course of the study, 64 patients were treated without knowledge of procalcitonin levels ("standard group") and 71 had their treatment based on measured procalcitonin levels ("PCT group"). Diagnoses were similar between the two groups -- about one-third pneumonia and one-quarter each acute bronchitis and acute exacerbations of chronic bronchitis.

The two groups had similar clinical outcomes, with no significant differences on evaluation by visual analog scale, white blood cell count, final procalcitonin level, percentage of patients hospitalized or number of hospital days, percentage of patients seen at follow-up, or number of deaths (3% in each group).

Use of antibiotics, however, was dramatically lower in the PCT group. In the standard group, 83% of the patients received antibiotics. In the PCT group, physicians expected on clinical grounds to give antibiotics to 80% of patients, but actually gave them to only 44% after obtaining procalcitonin data. In patients with pneumonia, usage was reduced from almost 100% to just over 90% (P=0.03). In those with bronchitis, there was a reduction from slightly over 50% to less than 20% (P=0.0003) and in patients with acute exacerbation of chronic bronchitis, the reduction was from almost 90% to slightly under 40% (P<0.001). Most strikingly, in the small group with asthma, antibiotic usage was reduced from close to 70% to almost zero (P=0.003).

"If [the procalcitonin level] is high, it is a clinically relevant bacterial infection that will profit from antibiotics," Dr. Oosterheert noted. "But if it's low, we say it's either viral or a non-clinically relevant bacterial infection, and we don't give antibiotics." The clinical severity has no influence, he added.

Dr. Oosterheert also noted that, in acute exacerbation of chronic bronchitis, 60% positive sputum cultures were found regardless of whether procalcitonin levels were high or low; yet those not treated with antibiotics because of low procalcitonin levels "cleared their infections perfectly," noted Dr. Oosterheert. "That means they were colonized with these bacteria, but [the bacteria] were not responsible for the infection."

Thus, he concluded, procalcitonin levels provide more diagnostic certainty than do standard methods.


[Study title: Early Procalcitonin Guided Diagnosis Markedly Reduces Antimicrobial Prescriptions in Acute Respiratory Tract Infections – The 'ProResp' Study. Abstract L-1587]

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