Procalcitonin-guided antibiotic use vs a standard approach for acute respiratory tract infections in primary care.

were restricted was 0.14 with procalcitonin-guided therapy (95% confidence interval [CI], �0.53 to 0.81 days), which met our criterion of an increase in days in which activities were restricted by no more than 1 day. With procalcitonin-guided therapy, the antibiotic prescription rate was 72% lower (95% CI, 66%-78%) than with standard therapy. Both approaches led to a similar proportion of patients reporting symptoms of ongoing or relapsing infection at 28 days (adjusted odds ratio, 1.0 [95% CI, 0.7-1.5]). Conclusions: As an adjunct to guidelines, procalcitoninguidedtherapymarkedlyreducesantibioticuseforacuterespiratory tract infections in primary care without compromising patient outcome. In practice, this could be achieved with1to2procalcitoninmeasurementsinpatientsforwhom the physician intends to prescribe antibiotics. Trial Registration: isrctn.org I dentifier: ISRCTN73182671