Bacterial superinfection in upper respiratory tract infections estimated by increases in CRP values: A diagnostic follow-up in primary care

Abstract

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. © 2008 Informa UK Ltd. (Informa Healthcare, Taylor & Francis AS).