Effect of a Diagnostic Algorithm for Urinary Tract Infection on Appropriate Use of Antibiotics and Diagnostics in General Practice - a Cluster Randomized Trial

STUDY DESIGN AND SETTING Cluster randomized controlled single blinded study of a diagnostic aid in general practice RECRUITMENT OF GENERAL PRACTICES Recruitment of general practices was done through online advertisement in email newsletters for general practice, invitation by post of 200 practices and invitation of 44 general practices already participating in a medical audit project regarding UTI (ref til Gloria). Only practices in the Capital Region of Denmark could participate.

RANDOMIZATION AND BLINDING Randomization was performed using an online random number generator and an employee not part of the investigation team sent out the diagnostic algorithm to the intervention group. The practices were asked not to reveal their allocation to the investigators in case of contact. Allocation was concealed to the investigators until after analysis of the primary outcomes.

INTERVENTION AND CONTROLS The practices in the intervention group received a laminated diagnostic algorithm by post and got access to a smart-phone integrated web-page, which could calculate post-test probabilities based on pre-test probabilities and accuracy of diagnostic tests .The diagnostic algorithm consists of three parts, one about urine dipstick, one about point-of-care microscopy and one about urine culture . The practices were instructed, use of the algorithm was voluntary. Control practices did not receive a diagnostic algorithm and did not have access to the smart-phone integrated web-page.

RECRUITMENT OF PATIENTS The practices were told to register diagnostics and treatment on the first 20-40 patients presenting in general practice with symptoms of UTI regardless of age, sex and comorbidity. For each patient, the practice sent a urine sample to the microbiological department as reference.

INCLUSION AND EXCLUSION CRITERIA Inclusion criteria were all patients with symptoms of UTI who had not formerly participated in the study and where urinalysis was performed. The only exclusion criterion was acute admission to hospital.