Guideline removal of atropine and survival after adult in-hospital cardiac arrest with a non-shockable rhythm

Aim: To determine whether the removal of atropine from the 2010 ACLS guidelines for non-shockable cardiac arrests was associated with a change in survival. Methods: Using the Get With The Guidelines^®-Resuscitation registry, we included adults with an index in-hospital cardiac arrest between 2006 and 2015. The primary outcome was survival to hospital discharge. Secondary outcomes included return of spontaneous circulation and favorable functional outcome. An interrupted time-series analysis was used to compare survival before (pre-guidelines) and after (post-guidelines) introduction of the 2010 guidelines. A difference-in-difference approach was used to compare the interrupted time-series results between the non-shockable and shockable cohorts to account for guideline changes unrelated to atropine. Results: We included 20,499 non-shockable and 3968 shockable cardiac arrests. Patient characteristics were similar between the pre-guidelines and post-guidelines period. Atropine was used for 8653 (87%) non-shockable and 680 (35%) shockable cardiac arrests in the pre-guidelines period and 3643 (35%) non-shockable and 320 (16%) shockable cardiac arrests in the post-guidelines period. The change over time in survival from the pre-guidelines to the post-guidelines period was not significantly different for the non-shockable compared to the shockable cohort (risk difference: 2.0% [95%CI: −0.8, 4.8] per year, p = 0.17). The immediate change in survival after introducing the guidelines was also not different between the cohorts (risk difference: 3.5% [95%CI: −2.6, 9.7], p = 0.26). Results were similar for the secondary outcomes and in multiple sensitivity analyses. Conclusions: The removal of atropine from the 2010 guidelines was not associated with a significant change in survival.