Lethal use of force surveillance: practical considerations for open-source database linkage.

Currently, there remains no reliable and timely government tracking in the USA of deaths caused by law enforcement. Federal efforts to track these events are insufficient, generally missing as many as half of community deaths that occur annually because of law enforcement's lethal use of force. The dearth of accurate data on these events limits the ability to accurately quantify their burden and effectively identify opportunities for intervention and policy change. The most reliable data sources on law enforcement related deaths among community members in the USA are publicly run (such as those run by the Washington Post and The Guardian newspapers) or crowdsourced systems, such as Fatal Encounters and Mapping Police Violence, which draw on both traditional and non-traditional sources of reporting and provide open-source access to users. We used successive deterministic and probabilistic linkage to merge these four databases. After exclusions, we found a total of 6333 deaths identified from 2013 to 2017. While most cases were identified by multiple databases, each database also found unique cases during their years of operation. The methodology described here emphasises the importance of these non-traditional data sources and can serve as a helpful resource to improve data accessibility and timeliness for public health agencies and others seeking to expand their study, understanding and response to this growing public health crisis.