Introduction: The STOP-MSU RCT of tranexamic acid (TXA) in ICH <2h onset was the first haemostatic trial to include recruitment on a Mobile Stroke Unit (MSU). Although the trial did not demonstrate benefit of TXA, we investigated haematoma growth and outcomes in participants receiving prehospital treatment on the MSU compared to hospital-recruited patients.
Methods: We conducted a post-hoc analysis of the STOP-MSU trial assuming neutral treatment effect. We compared MSU-recruited to hospital-recruited patients for treatment time and haematoma growth (dichotomised 33%/6ml or absolute growth) and 90-day mRS (adjusted for age, sex, NIHSS and baseline ICH volume).
Results: Of n=201 trial patients, 44(21.9%) were recruited on MSU. There were no significant differences in baseline demographics including age, location, baseline volume, BP or glucose. MSU-recruited patients received faster treatment from onset (76min[IQR 67.5-100] vs 107min[IQR 97-118],p<0.001) and were treated more frequently ≤60min (OR 15.0[95%CI 3.0-75.1]). MSU patients had higher rates of growth on both dichotomised (52.3% vs 36.3%,aOR 2.0[95%CI 1.0-4.2],p=0.062) and absolute criteria (median 3.3ml[IQR 0.5-17.8] vs 0.8ml[IQR -0.8-6.5], mean 16.0ml[SD28.5] vs 7.0[SD15.4]). MSU patients trended towards poorer outcomes for mRS 0-3/return-to-baseline (40.9% vs 52.2%,aOR 0.75[95%CI 0.33-1.71]) and mortality (25.0% vs 14.7%,aOR 1.3[95%CI 0.4-3.8] with no modification from TXA (p-interaction=0.07).
Conclusions: MSU-recruited patients received significantly faster treatment and showed a two-fold increased odds of haematoma growth compared to hospital-recruited patients. Growth parameters were comparable or even surpassed previous TXA trials that required CTA spot-sign for eligibility. As such MSU-facilitated ultra-early recruitment may be key for optimal patient selection in acute ICH trials.