The SITS-UTMOST: A registry-based prospective study in Europe investigating the impact of regulatory approval of intravenous Actilyse in the extended time window (3–4.5 h) in acute ischaemic stroke

Introduction The SITS-UTMOST (Safe Implementation of Thrombolysis in Upper Time window Monitoring Study) was a registry-based prospective study of intravenous alteplase used in the extended time window (3–4.5 h) in acute ischaemic stroke to evaluate the impact of the approval of the extended time window on routine clinical practice. Patients and methods Inclusion of at least 1000 patients treated within 3–4.5 h according to the licensed criteria and actively registered in the SITS-International Stroke Thrombolysis Registry was planned. Prospective data collection started 2 May 2012 and ended 2 November 2014. A historical cohort was identified for 2 years preceding May 2012. Clinical management and outcome were contrasted between patients treated within 3 h versus 3–4.5 h in the prospective cohort and between historical and prospective cohorts for the 3 h time window. Outcomes were functional independency (modified Rankin scale, mRS) 0–2, favourable outcome (mRS 0–1), and death at 3 months and symptomatic intracerebral haemorrhage (SICH) per SITS. Results 4157 patients from 81 centres in 12 EU countries were entered prospectively (N = 1118 in the 3–4.5 h, N = 3039 in the 0–3 h time window) and 3454 retrospective patients in the 0–3 h time window who met the marketing approval conditions. In the prospective cohort, median arrival to treatment time was longer in the 3–4.5 h than 3 h window (79 vs. 55 min). Within the 3 h time window, treatment delays were shorter for prospective than historical patients (55 vs. 63). There was no significant difference between the 3–4.5 h versus 3 h prospective cohort with regard to percentage of reported SICH (1.6 vs. 1.7), death (11.6 vs. 11.1), functional independency (66 vs. 65) at 3 months or favourable outcome (51 vs. 50). Discussion Main weakness is the observational design of the study. Conclusion This study neither identified negative impact on treatment delay, nor on outcome, following extension of the approved time window to 4.5 h for use of alteplase in stroke.