Clot-busting devices administered through the artery do not improve victims’ chances of living independently after a stroke, according to research published Thursday.

Researchers funded by the National Institute of Neurological Disorders and Stroke (NINDS) undertook a controlled trial with 656 participants. Between 2006-2012, some of the participants received standard drug therapy of intravenous tissue plasminogen activator (tPA). Others received tPA as well as intra-arterial treatment, in which a catheter run through an artery administers tPA directly to large clots in the brain.

Both groups had a similar statistical likelihood of living independently within 90 days of stroke, the researchers found. Of those who received IV tPA alone, 39% were functionally independent within three months. Among the other group, that number was 41%.

The rate of victim disability was similar, even though intra-arterial treatment is 40% more effective than IV tPA at clot removal, the researchers found. However, intra-arterial therapy is also risky, with 16% of study participants experiencing complications.