Objective: The aim of this study was to estimate the rate of bacterial superinfection in patients with URTI by using on-site determination of C-reactive protein (CRP).
Design: A prospective cohort study.
Setting: A total of 30 primary care practices.
Subjects: Patients with URTI.
Intervention: The CRP value was determined at the first consultation and at a follow-up within 3-5 days. CRP values of 30 units (mg) or higher were considered to be an indication of bacterial involvement.
Main outcome measures: CRP values during follow-up and duration of illness.
Results: Among the 506 patients included, 73.1% exhibited a CRP value below the defined limit at their first visit and were considered to suffer from URTI of viral origin. The rate of subsequent bacterial superinfection was 8.1%. Compared with patients suffering from URTI of bacterial or viral origin the duration of illness in patients with bacterial superinfection was significantly longer.
Conclusion: During follow-up of patients with URTI, the prevalence of bacterial superinfection detected by using a near patient CRP determination is surprisingly low. This result should help to reduce the prescription rate of antibiotics in primary care.