Introduction: Stroke shortens an individual’s disability-free life. We aimed to assess the relative prognostic influence of pre- and post-treatment perfusion CT imaging variables (e.g. ischemic core and penumbral volumes) compared to standard clinical predictors (such as onset-to-treatment time) on long-term stroke disability in patients undergoing thrombolysis.
Methods: We used data from a prospectively collected international, multicenter, observational registry of acute ischemic stroke patients who had perfusion CT and CT angiography before treatment with intravenous alteplase. Baseline perfusion CT and follow-up MRI were analysed to derive the baseline penumbra volume, baseline ischemic core volume, and penumbra salvaged from infarction. The primary outcome measure was the effect of imaging and clinical variables on disability-adjusted life years (DALY). Clinical variables were age, sex, NIHSS score, and onset-to-treatment time. Age, sex, country, and 3-month modified Rankin Scale were extracted from the registry to calculate DALY due to stroke, such that one year of DALY equates to 1 year of healthy life lost due to stroke.
Results: Seven hundred seventy two patients were treated with alteplase therapy. 17.5 DALY-days were lost per 1 mL of baseline ischemic core volume (95%CI, 13.2 - 21.9 days, p < 0.001). For every mL of penumbra salvaged, 7.2 days of DALY-days were saved (95%CI, 4.1 - 10.4 days, p < 0.001). Each minute of earlier onset-to-treatment time resulted in a saving of 4.4 disability-free days after stroke (1.3 - 7.5 days, p = 0.006). However, after adjustment for imaging variables, onset-to-treatment time was not significantly associated with savings in DALY-days.
Conclusions: Pre-treatment perfusion CT scan defined penumbra (independently of clinical variables) predict significant gains, or loss, of disability-free life in patients undergoing reperfusion therapy for stroke. The effect of earlier treatment on disability-free life appears explained by salvage of penumbra.