Frequent readers of this site will be familiar with my distaste for TPA in stroke – not because I think it’s a therapeutically invalid option, but mostly because its use is being promoted beyond its original scope, too many stroke mimics are receiving TPA, and the published literature supporting new “innovations” in TPA have a skewed interpretation of “safe”.
This paper from Stroke is the first I’ve seen that finally tries to determine whether a patient will actually benefit from TPA in acute ischemic stroke, rather than chaining together studies in a logical fallacy to extend treatment to a larger population. These authors have developed the “iScore” (no affiliation with Apple Computer), which was developed by logistic regression to predict outcomes in patients with ischemic stroke not treated with TPA. The components include age, stroke severity, stroke subtype, and medical comorbidities in a scoring system that defines low (>50% good outcome), moderate (10-50%), and high-risk (<10%) groups.
These authors then apply the iScore in a retrospective fashion to their stroke database, looking both at their TPA recipients as well as propensity-matched patients in their non-TPA group. Now, it’s not exactly prospective, randomized, controlled, but it’s an interesting trick that provides a limited comparison. The stroke patients in the low-risk group had ~12% absolute outcomes benefit from TPA, the, the moderate group ~10% benefit, and the high-risk group ~2.6%. There were no statistically significant benefits (or harms) from TPA in the high-risk group, but those patients were >90% disabled or dead at 30 days, regardless of therapy.
One weakness the authors point out in their study – it is sometimes clinically difficult to determine stroke subtype in the acute setting based solely off clinical presentation, particularly when baseline functional status is not perfect. Regardless, it’s nice to see a paper that looks at better individualizing the risk/benefit equation for TPA – seems as though the 400 patients in the high-risk group did not benefit from spending $2000 on alteplase or the associated increased DRG billing associated with it. Money isn’t free, after all….
“The iScore Predicts Effectiveness of Thrombolytic Therapy for Acute Ischemic Stroke”
http://stroke.ahajournals.org/content/early/2012/02/02/STROKEAHA.111.646265.short