The role of mathematical modelling in aiding public health policy decision-making: A case study of the BC opioid overdose emergency.

The province of British Columbia is currently experiencing the highest rate of apparent opioid-related deaths within Canada. This dramatic increase in overdose deaths has been primarily driven by the increase of fentanyl and fentanyl-analogues within the unregulated, highly unpredictable and toxic street drug supply. A public health emergency was declared in B.C. in April 2016. After the emergency was declared, overdose-related death rates continued to rise, reaching unprecedented levels. In the context of enhanced collaboration between government organizations and researchers, a series of mathematical studies improved the ability of government and service providers to understand the impact of scaled-up strategies, including harm reduction and treatment services. In this commentary we describe how government agencies collaborated with researchers and other experts to use modelling results, and describe lessons learned for enhancing these collaborations. Mathematical modelling provides a viable and timely approach to the generation of intelligence, combining disparate data to assess the on-going impact of a comprehensive package of interventions during a public health emergency, and enhancing accountability for investments.