Use of VetCompass Australia data to estimate body weight for antimicrobial stewardship in Australian dogs

Evaluation of the appropriateness of antimicrobial use requires multiple data elements, including the indication for treatment, duration of therapy and dose of the drug used. To calculate the dose the volume of active ingredient and animal weight are required. Dog weight is frequently missing from the electronic medical records from the VetCompass Australia database. Electronic clinical records were extracted from VetCompass Australia for the top 10 breeds of dogs in the database where weight, age and sex were recorded (n = 72,089). The mean weight for age and sex was calculated for each breed. In a second cohort, animals aged greater than 1 year that had weight recorded and were prescribed an antimicrobial were extracted (n = 69,683). The total milligrams of antimicrobial administered were extracted using previously described tools. The true weight and the breed/sex/age average were then used to assess the appropriateness of antimicrobial doses. Antimicrobial doses were compared to those recommended in the Australian Veterinary Prescribing Guidelines from the University of Melbourne. There were 46,172 appropriate doses of antimicrobials in cohort 2 (66% appropriateness). The true positive rate for VetCompass Australia approximated weight was 82%. The true negative rate for VetCompass Australia approximated weight was 78%. Subgroup mean imputation is a reasonably accurate method of dealing with missing data for determining the appropriateness of antimicrobial dose for population level studies.