Dr Natasa Gisev is a clinical pharmacist and Scientia Senior Lecturer at the National Drug and Alcohol Research Centre, UNSW Sydney. Her research interests lie in the use of big data and data linkage to evaluate medicines use and corresponding benefits/harms among populations with complex health care needs, including older adults and those with mental health and substance use disorders. The ultimate goal of her work is to improve the quality use of medicines and clinical outcomes in these populations. Her work has influenced national and international policy and practice in the delivery of mental health treatment services, as well as the upscaling of treatment services for opioid dependence. She is currently leading a programme of work focused on establishing population-based evidence on the long-term outcomes of prescribed opioid use, including the risk of developing dependence, overdose, and other harms.