{"id":5760,"date":"2016-03-26T09:24:21","date_gmt":"2016-03-26T09:24:21","guid":{"rendered":"http:\/\/www.420magazine.com\/?p=4589"},"modified":"2016-03-26T09:24:21","modified_gmt":"2016-03-26T09:24:21","slug":"new-study-suggests-marijuanas-impact-on-crash-risk-has-been-greatly-exaggerated","status":"publish","type":"post","link":"https:\/\/cannitrol.com\/blog\/new-study-suggests-marijuanas-impact-on-crash-risk-has-been-greatly-exaggerated\/","title":{"rendered":"New Study Suggests Marijuana\u2019s Impact On Crash Risk Has Been Greatly Exaggerated"},"content":{"rendered":"<div id=\"wp_fb_like_button\" style=\"margin:5px 0 5px 5px;float:right;height:100px;\"><script src=\"http:\/\/connect.facebook.net\/en_US\/all.js#xfbml=1\"><\/script><fb:like href=\"https:\/\/cannitrol.com\/blog\/new-study-suggests-marijuanas-impact-on-crash-risk-has-been-greatly-exaggerated\/\" send=\"true\" layout=\"standard\" width=\"450\" show_faces=\"false\" font=\"arial\" action=\"like\" colorscheme=\"light\"><\/fb:like><\/div><p>Pot prohibitionists frequently warn that legalization will flood the roads with dangerously stoned drivers, leading to a surge in traffic fatalities. So far there is not much evidence of such a surge in Colorado or Washington, where marijuana was legalized in 2012. A new study may help explain why: It looks like marijuana\u2019s impact on traffic safety has been greatly exaggerated.<\/p>\n<p>Reporters and anti-pot activists commonly warn that marijuana use doubles the risk of a car crash. Even if that were true, toking would pale in comparison to drinking as a road hazard, since research indicates that a blood alcohol concentration of 0.10% quintuples the risk of an accident. But according to an analysis that\u2019s about to be published by the journal Addiction, the increase in crash risk associated with marijuana use is roughly 20% to 30%, as opposed to the widely cited estimate of 92%.<\/p>\n<p>That estimate comes from a 2012 BMJ meta-analysis by Canadian epidemiologist Mark Asbridge and two of his colleagues at Dalhousie University in Halifax. Ole Rogeberg and Rune Elvik\u2014who work, respectively, at the Ragnar Frisch Center for Economic Research and the Norwegian Center for Transport Research, both in Oslo\u2014did a new meta-analysis of the nine studies covered by the BMJ article, taking into account additional confounding variables. As they explain, \u201cUsing cannabis and driving under the influence are behaviours that are more common among young adults and males, groups with higher crash risks irrespective of use. Estimated odds ratios typically decline substantially after adjustments for such factors.\u201d That is what happened in this case, and it\u2019s the main reason Rogeberg and Elvik\u2019s results differ from Asbridge\u2019s.<\/p>\n<p>Rogeberg and Elvik also took another look at a 2012 Epidemiologic Reviews article, likewise based on a meta-analysis of nine studies, in which Mu-Chen Li and other researchers at Columbia University\u2019s medical school estimated that marijuana use increases crash risk by 166%. Rogeberg and Elvik found that \u201cthe pooled studies report qualitatively different types of associations: Self-reported crashes in some past period for cannabis ever-users vs. never-users, self-reported crashes in a past period for those with self-reported intoxicated driving episodes in the past vs. those without, and acute intoxication amongst crash-involved and other motorists.\u201d They conclude that \u201cthe lack of clear study selection criteria\u2026gives the resulting pooled estimate no meaningful interpretation.\u201d<\/p>\n<p>In addition to reanalyzing the data from the earlier reviews, Rogeberg and Elvik did a fresh meta-analysis of 21 studies. The new analysis generated two estimates of the crash risk increase associated with marijuana use (based on two different statistical methods): 22% and 36%. \u201cThe replication of Asbridge et al. and Li et al.,\u201d Rogeberg and Elvik write, \u201cindicates that their published pooled estimates substantially overestimated the effect of acute cannabis intoxication on crash risk, and that the pooled estimate presented by Li et al. is hard to interpret given the qualitatively different estimates pooled. The revised estimate from the studies used in Asbridge et al. was in line with the results from the expanded meta-analysis\u2026lying in between the pooled odds from the mixed-effects model of 1.36\u2026and the pooled odds from the PEESE meta-regression of 1.22.\u201d<\/p>\n<p><a href=\"https:\/\/cannitrol.com\/blog\/\/wp-content\/uploads\/2016\/03\/new-study-suggests-marijuanas-impact-on-crash-risk-has-been-greatly-exaggerated.jpg\" rel=\"attachment wp-att-4590\"><img loading=\"lazy\" class=\"size-full wp-image-4590 aligncenter\" src=\"https:\/\/cannitrol.com\/blog\/\/wp-content\/uploads\/2016\/03\/new-study-suggests-marijuanas-impact-on-crash-risk-has-been-greatly-exaggerated.jpg\" alt=\"maxresdefault\" width=\"737\" height=\"400\" \/><\/a>News Moderator: Robert Celt <a href=\"http:\/\/www.420magazine.com\/\" target=\"_blank\">420 MAGAZINE \u00ae<\/a><br \/>\nFull Article: <a href=\"http:\/\/www.forbes.com\/sites\/jacobsullum\/2016\/03\/17\/new-study-suggests-marijuanas-impact-on-crash-risk-has-been-greatly-exaggerated\/#10b85e931906\" target=\"_blank\">New Study Suggests Marijuana&#8217;s Impact On Crash Risk Has Been Greatly Exaggerated<\/a><br \/>\nAuthor: Jacob Sullum<br \/>\nContact: <a href=\"http:\/\/www.forbes.com\/fdc\/contact.html\" target=\"_blank\">Forbes<\/a><br \/>\nPhoto Credit: None found<br \/>\nWebsite: <a href=\"http:\/\/www.forbes.com\/\" target=\"_blank\">Forbes<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Pot prohibitionists frequently warn that legalization will flood the roads with dangerously stoned drivers, leading to a surge in traffic&#8230; <a href=\"http:\/\/www.420magazine.com\/2016\/03\/new-study-suggests-marijuanas-impact-crash-risk-greatly-exaggerated\/\" class=\"read-more\">[Read More]<\/a> <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1597,9,1,3],"tags":[4165],"_links":{"self":[{"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/posts\/5760"}],"collection":[{"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/comments?post=5760"}],"version-history":[{"count":0,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/posts\/5760\/revisions"}],"wp:attachment":[{"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/media?parent=5760"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/categories?post=5760"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/tags?post=5760"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}