IMPORTANCE: The Stroke Prognostication using Age and the NIH Stroke Scale index, 
created by combining age in years plus a National Institutes of Health (NIH) 
Stroke Scale score of 100 or higher (and hereafter referred to as the SPAN-100 
index), is a simple risk score for estimating clinical outcomes for patients 
with acute ischemic stroke (AIS). The association between this index and 
response to intravenous thrombolysis for AIS has not been properly evaluated.
OBJECTIVE: To assess the relationship between SPAN-100 index status and outcome 
following treatment with intravenous thrombolysis for AIS.
DESIGN, SETTING, AND PARTICIPANTS: Using the Virtual International Stroke Trials 
Archive (VISTA) database, an international repository of clinical trials data, 
we assessed the SPAN-100 index among 7093 patients with AIS who participated in 
4 clinical trials from 2000 to 2006. The SPAN-100 index is considered positive 
if the sum of the age and the NIH Stroke Scale (a 15-item neurological 
examination scale with scores ranging from 0 to 42, with higher scores 
indicating more severe strokes) score is greater than or equal to 100. 
Multivariable logistic regression analyses were used to determine the 
independent association between SPAN-100 index status and 90-day outcomes.
MAIN OUTCOMES AND MEASURES: The primary outcome was a composite of severe 
disability or death measured 90 days after stroke, and the secondary outcomes 
were death alone and a composite of no disability/modest disability.
RESULTS: Of 7093 patients, 743 (10.5%) were SPAN-100 positive, and 2731 (38.5%) 
received intravenous thrombolysis. Compared with SPAN-100-negative patients, 
SPAN-100-positive patients were more likely to experience a catastrophic outcome 
(adjusted odds ratio [AOR], 9.03 [95% CI, 6.68-12.21]) or death alone (AOR, 5.03 
[95% CI, 4.06-6.23]) and less likely to experience a favorable outcome (AOR, 
0.08 [95% CI, 0.06-0.13]). However, there was an interaction between SPAN-100 
index status and thrombolysis treatment (P < .001) revealing a reduction in the 
likelihood of severe disability/death with thrombolytic treatment for 
SPAN-100-positive (AOR, 0.46 [95% CI, 0.29-0.71]) but not SPAN-100-negative 
patients (AOR, 0.96 [95% CI, 0.85-1.07]). Similar interactions between SPAN-100 
index status and thrombolysis treatment were observed for the 2 secondary 
outcomes.
CONCLUSION AND RELEVANCE: Compared with the SPAN-100-negative patients with AIS, 
the SPAN-100-positive patients with AIS seem to have poorer 3-month outcomes but 
may derive greater benefit when treated with intravenous thrombolysis. The 
SPAN-100-positive patients are often excluded from AIS clinical trials but 
should probably not be denied thrombolysis treatment on the basis of such a 
profile alone.