Risk Factors for Unnecessary Antibiotic Therapy: A Major Role for Clinical Management

Introduction: Assessment of antimicrobial use places an emphasis on therapeutic aspects of infected patients. Our aim was to determine the risk factors for unnecessary antibiotic therapy (UAT). Methods: This was a prospective, multicentre study evaluating all curative antibiotic therapies prescribed over two consecutive days through the same electronic medical records. Each item that could participate in the antibiotic prescriptions was collected from the computerized file: the reason for hospitalization, comorbid conditions, suspected or definitive diagnosis of infection, microbial analyses. UAT was defined as the recognition of non-infectious syndromes, non-bacterial infections, use of redundant antimicrobials, and continuation of empirical broad-spectrum antimicrobials. Results: Four hundred fifty-three antibiotic therapies were analysed at 17 institutions. An infectious disease was the reason for hospitalization in 201 cases (44%). An unspecified diagnosis of infection was observed in 104 cases (23%). Microbial samples were taken in 296 cases (65%), allowing isolation of a pathogen in 156 cases (53%). Unspecified diagnosis was associated with the absence of a microbial sample: 56/104 (54%) versus 240/349 (69%), p = 0.005. A total of 158 non-infectious syndromes were observed (35%). UAT was observed in 169 cases (37%), due to non-infectious syndromes in 106 cases. In multivariate analysis, the modifiable risk factors for UAT were unspecified diagnosis: AOR = 1.83 [1.04-3.20], and absence of a blood culture: AOR = 5.26 [2.56-10.00]. Conclusion: Unnecessary antibiotic therapy is associated with an unspecified diagnosis and the absence of microbial testing. Antimicrobial stewardship programmes should focus on diagnostic difficulties and microbial testing, with the latter facilitating antibiotic reassessment and therapeutic interruption.