PT - JOURNAL ARTICLE AU - Harper, Sam AU - Palayew, Adam TI - The annual cannabis holiday and fatal traffic crashes AID - 10.1136/injuryprev-2018-043068 DP - 2019 Oct 01 TA - Injury Prevention PG - 433--437 VI - 25 IP - 5 4099 - http://injuryprevention.bmj.com/content/25/5/433.short 4100 - http://injuryprevention.bmj.com/content/25/5/433.full SO - Inj Prev2019 Oct 01; 25 AB - Background Cannabis use has been linked to impaired driving and fatal accidents. Prior evidence suggests the potential for population-wide effects of the annual cannabis celebration on April 20th (‘4/20’), but evidence to date is limited.Methods We used data from the Fatal Analysis Reporting System for the years 1975–2016 to estimate the impact of ‘4/20’ on drivers involved in fatal traffic crashes occurring between 16:20 and 23:59 hours in the USA. We compared the effects of 4/20 with those for other major holidays, and evaluated whether the impact of ‘4/20’ had changed in recent years.Results Between 1992 and 2016, ‘4/20’ was associated with an increase in the number of drivers involved in fatal crashes (IRR 1.12, 95% CI 0.97 to 1.28) relative to control days 1 week before and after, but not when compared with control days 1 and 2 weeks before and after (IRR 1.05, 95% CI 0.92 to 1.28) or all other days of the year (IRR 0.98, 95% CI 0.88 to 1.10). Across all years we found little evidence to distinguish excess drivers involved in fatal crashes on 4/20 from routine daily variations.Conclusions There is little evidence to suggest population-wide effects of the annual cannabis holiday on the number of drivers involved in fatal traffic crashes.