In Reply: In response to Drs Cals and Metlay, we note that in addition to the ProHOSP trial, which was performed mainly in hospitalized patients, a randomized controlled trial in primary care was conducted in a region with very low antibiotic use, where communication training was not able to further reduce antibiotics.1,2 With PCT-guided therapy, participating clinicians were able to reduce the antibiotic prescription rate by 72% more than by clinical judgment combined with routine laboratory workup, including CRP measurements. Despite this markedly reduced antibiotic exposure in the PCT group, the clinical outcome was similar in both groups. The study by Cals et al3 showed a 42% relative reduction in antibiotic use with CRP guidance, similar to the effect of communication training. We agree that a head to head trial comparing different point-of-care strategies in primary care is needed. However, the usefulness of CRP for antibiotic guidance outside the primary care setting is not supported by controlled intervention trials and is hampered by a lower specificity, delayed response with late peak levels, and modulation by anti-inflammatory drugs such as corticosteroids.4 To obtain more evidence related to the effect of PCT guidance outside of controlled study conditions, we are currently performing an observational multinational quality surveillance study in hospitals and general practitioner offices in Europe (ISRCTN40854211).
Schuetz P, Zimmerli W, Mueller B. Procalcitonin-Based Guidelines and Lower Respiratory Tract Infections—Reply. JAMA. 2010;303(5):418-420. doi:10.1001/jama.2010.54