Background The use of C-reactive protein (CRP) tests is shown to safely reduce antibiotic prescribing for acute respiratory tract infections (RTIs). The aim of this study was to explore patient and clinical factors associated with the use of CRP testing when prescribing antibiotics recommended for RTIs.
Methods A nation-wide retrospective cross-sectional register-based study based on first redeemed antibiotic prescriptions issued to adults in Danish general practice between July 2015 and June 2017. Only antibiotics recommended for treatment of RTIs were included in the analysis (penicillin-V, amoxicillin, co-amoxicillin or roxithromycin/clarithromycin). Logistic regression models were used to estimate odds ratios for patient-related and clinical factors on performing a CRP test in relation to antibiotic prescribing.
Results A total of 984,149 patients redeemed at least one antibiotic prescription during the two-year period. Of these, 487,939 (49.6%) were labelled with the clinical indication RTI. Patients aged 75 years and above, with a Charlson Comorbidity Index of more than one, unemployed or on disability pension, living alone, and immigrants or descendants of immigrants had lower odds of having a CRP test performed in relation to an antibiotic prescription. Being followed in practice for a chronic condition and having CRP tests performed in the previous year were associated with higher odds of CRP testing in relation to antibiotic prescribing.
Conclusions Differences were observed in the use of CRP tests among subgroups of patients indicating that both sociodemographic factors and comorbidity influence the decision to use a CRP test in general practice. Potentially, this means that CRP tests are not used to an optimal extent for all groups of patients. This leaves room for improved use of CRP tests to increase diagnostic certainty and further promote rational prescribing of antibiotics.