Police and hospital data linkage for traffic injury surveillance: A systematic review.

• Use of multiple data sources can enable more complete and informative road injury statistics. • The papers reviewed lack consistency in what was reported and how. • Probabilistic methods are more common when linking administrative data on crash injuries. • Linkage studies can identify topics and case types that warrant more attention in road safety programs, commonly including vulnerable road users. This systematic review examines studies of traffic injury that involved linkage of police crash data and hospital data and were published from 1994 to 2023 worldwide in English. Inclusion and exclusion criteria were the basis for selecting papers from PubMed, Web of Science, and Scopus, and for identifying additional relevant papers using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and supplementary snowballing (n = 60). The selected papers were reviewed in terms of research objectives, data items and sample size included, temporal and spatial coverage, linkage methods and software tools, as well as linkage rates and most significant findings. Many studies found that the number of clinically significant road injury cases was much higher according to hospital data than crash data. Under-estimation of cases in crash data differs by road user type, pedestrian cases commonly being highly under-counted. A limited number of the papers were from low- and middle-income countries. The papers reviewed lack consistency in what was reported and how, which limited comparability. [ABSTRACT FROM AUTHOR]