What a difference a CRP makes. A prospective observational study on how point-of-care C-reactive protein testing influences antibiotic prescription for respiratory tract infections in Swedish primary health care

Objective: To explore how C-reactive protein (CRP) tests serve to support physicians in decisions concerning antibiotic prescription to patients with respiratory tract infections (RTI). Design. Prospective observational study. Setting: Primary health care centres in western Sweden. Subjects. Physicians in primary health care. Patients with acute RTI. Main outcome measures: Physician willingness to measure CRP, their ability to estimate CRP, and changes in decision-making concerning antibiotic treatment based on error estimate and the physician’s opinion of whether CRP measurement was crucial. Results: Data from 340 consultations were gathered. CRP testing was found to be crucial in 130 cases. In 86% of visits decisions regarding antibiotic prescription were unchanged. Physicians considering CRP crucial and physicians making an error estimate of CRP altered their decisions concerning antibiotic prescription after CRP testing more often than those who considered CRP unnecessary, and those making a more accurate estimate. Physicians changed their decision on antibiotic prescription in 49 cases. In the majority of these 49 cases physicians underestimated CRP levels, and the majority of changes were from “no” to “yes” as to whether to prescribe antibiotics. Conclusion: CRP is an important factor in the decision on whether to prescribe antibiotics for RTIs. Error estimates of CRP and willingness to measure CRP are important factors leading to physicians changing decisions on antibiotic treatment. KEY POINTS: There is a generally low antibiotic prescription rate and a high frequency of C-reactive protein (CRP) testing for respiratory tract infections (RTIs) in Sweden. CRP testing was considered essential to further management in 38% of cases. In 86% of visits decisions concerning antibiotic prescription were unchanged. The strongest predictors for revised decisions on antibiotic treatment were error estimates of CRP and the physician’s opinion that CRP measurement was crucial.