{"id":543,"date":"2018-12-17T10:38:45","date_gmt":"2018-12-17T10:38:45","guid":{"rendered":"https:\/\/www.transplantevidence.com\/news\/?p=543"},"modified":"2018-12-17T10:38:45","modified_gmt":"2018-12-17T10:38:45","slug":"immortal-time-bias-in-survival-analysis","status":"publish","type":"post","link":"https:\/\/www.transplantevidence.com\/news\/2018\/12\/17\/immortal-time-bias-in-survival-analysis\/","title":{"rendered":"Immortal time bias in survival analysis"},"content":{"rendered":"<p>Whilst reviewing an article submitted to a transplant journal recently, my attention was brought to an issue that is often overlooked in survival analysis, called &#8216;immortal time bias&#8217;.  The issue arises when the groups to be compared in the analysis are defined by a time-dependent event that can occur any time during follow-up. As standard survival analysis assumes that the risk is present at the start of the observation period, this can lead to biased survival estimates; if the intervention\/exposure is beneficial, the survival advantage can be overestimated, and if it is detrimental then the survival disadvantage may be underestimated.<\/p>\n<p>For an excellent description of the problem, and potential solutions, take a look at <a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/full\/10.1111\/tri.13081\" target=\"_blank\">this excellent article<\/a> in Transplant International from Gleiss et al.  The example given examines the effect of graft survival on post-transplant patient survival, but the problem would also apply to other transplant analyses, such as the effect of acute rejection on graft survival.<\/p>\n<p>A must for anyone undertaking registry analyses!<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Whilst reviewing an article submitted to a transplant journal recently, my attention was brought to an issue that is often overlooked in survival analysis, called &#8216;immortal time bias&#8217;. The issue arises when the groups to be compared in the analysis are defined by a time-dependent event that can occur any time during follow-up. As standard [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[168,176],"tags":[330,329,328],"class_list":["post-543","post","type-post","status-publish","format-standard","hentry","category-journals","category-registry-data","tag-bias","tag-immortal-time","tag-survival-analysis"],"_links":{"self":[{"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/posts\/543","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/comments?post=543"}],"version-history":[{"count":1,"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/posts\/543\/revisions"}],"predecessor-version":[{"id":544,"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/posts\/543\/revisions\/544"}],"wp:attachment":[{"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/media?parent=543"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/categories?post=543"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.transplantevidence.com\/news\/wp-json\/wp\/v2\/tags?post=543"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}