Clinical characteristics and diagnostic accuracy of preliminary diagnoses in adults with infections in Danish emergency departments: a multicentre combined cross-sectional and diagnostic study

OBJECTIVE: Rapid and accurate infection diagnosis is a prerequisite for appropriate antibiotic prescriptions in an ED. Accurately diagnosing acute infections can be difficult due to nonspecific symptoms and limitations of diagnostic testing. The accuracy of preliminary diagnoses, established on the initial clinical assessment, depends on a physician's skills and knowledge. It has been scarcely studied, and knowledge of how infected patients present at EDs today is needed to improve it. Based on expert reference diagnoses and a current ED population, this study aimed to characterise adults presenting at EDs with suspected infection to distinguish between infections and non-infections and to investigate the accuracy of the preliminary infection diagnoses. DESIGN: This study was multicentre with a design that combined a cross-sectional study and a diagnostic study with a prospective enrolment. SETTING: Multicenter study including EDs at three Danish hospitals. PARTICIPANTS: Adults admitted with a preliminary diagnosis of an infectious disease. OUTCOME MEASURES: Data were collected from medical records and participant interviews. The primary outcome was the reference diagnosis made by two medical experts on chart review. Univariate logistic regression analysis was performed to identify factors associated with infectious diseases. RESULTS: We included 954 patients initially suspected of having an infection, with 81% later having an infectious disease confirmed by experts. Parameters correlating to infection were fever, feeling unwell, male sex, high C-reactive protein, symptoms onset within 3 days, high heart rate, low oxygen saturation and abnormal values of neutrophilocytes and leucocytes. The three main conditions were community-acquired pneumonia (CAP) (34%), urinary tract infection (UTI) with systemic symptoms (21%) and cellulitis (10%). The sensitivity of the physician's preliminary infection diagnoses was 87% for CAP, 74% for UTI and 77% for other infections. CONCLUSIONS: Four out of five patients with a preliminary infection diagnosis, established on initial clinical assessment, were ultimately confirmed to have an infectious disease. The main infections included CAP, UTI with systemic symptoms and cellulitis. Physicians' preliminary infection diagnoses were moderately in accordance with the reference diagnoses. TRIAL REGISTRATION NUMBER: NCT04661085, NCT04681963, NCT04667195.