With an increasingly aging population, patients have more health conditions and are taking more medicines. GPs have limited time to treat patients and do not often review appropriate prescribing with complex patients. We will design and test an electronic tool using patient data, e.g. demographics and blood test results, to assist GPs to review medicines and prescribe appropriately. The tool will be developed by BPACnz to work with existing patient management programmes and trialled in two GP practices. These practices will be compared to similar practices to assess if the tool results in patients receiving medicines that are appropriate, and fewer hospital admissions/deaths. We will count how often GPs use the tool and follow recommendations. We expect that this tool can be integrated into most GP practices in New Zealand to help manage patient prescribing, resulting in improved outcomes for patients and for the health system.