Hemorrhage after thrombolytic therapy for stroke: the clinically relevant number needed to harm

A clinically relevant number needed to harm for tissue plasminogen activator (tPA)-related symptomatic intracerebral hemorrhage (SICH) would greatly assist therapeutic decision-making.

A 15-variable prognostic model was derived from a placebo group enrolled in National Institute of Neurological Disorders and Stroke tPA Trials 1 and 2 and used to predict final global disability outcome for patients with tPA-related SICH had they been treated with placebo, rather than tPA, and not experienced SICH.

Among 312 tPA-treated patients, 20 experienced SICH. Compared with placebo patients, patients treated with tPA who experienced SICH were older, had more severe stroke deficits, had higher serum glucose levels, and more often displayed mass effect on pretreatment imaging. Observed 3-month modified Rankin Scale outcomes among the patients experiencing SICH after tPA were: 0-5%, 1-5%, 4-10%, 5-5%, and 6-75%. Predicted outcomes had they been treated with placebo were: 0-2%, 1-5%, 2-7%, 3-14%, 4-28%, 5-12%, and 6-32%. The number needed to harm for one more patient to have a final disabled or dead outcome (modified Rankin Scale > or =3) attributable to tPA-related SICH was 707. Number needed to harm for severely disabled or dead outcome (modified Rankin Scale > or =4) was 126; for fatal outcome 36.5, and for worsened outcome by any degree (> or =1 modified Rankin Scale grade) between 29.7 and 40.1.

Most patients who experience SICH have severe baseline infarcts and already are destined for poor outcomes. For every 100 patients treated with tPA, approximately 1 will experience a severely disabled or fatal final outcome as a result of tPA-related SICH.