Weight approximation in stroke before thrombolysis: the WAIST-Study: a prospective observational "dose-finding" study.

Background and Purpose: Because of the narrow therapeutic range for thrombolysis in stroke, accurate weight-based dosing is essential for efficacy and safety. Stroke patients are frequently incapable to communicate their correct body weight (BW). Thus, dosing is often based on BW estimation, which may lead to dosing errors. The aim of our study was to evaluate availability of BW information, accuracy of estimations, and final dosing of Alteplase (tissue plasminogen activator [tPA]) in a routine clinical setting.
Methods: A total of 109 consecutive intravenous thrombolysis patients were prospectively included in the study. Recruitment concluded with 100 complete data sets. Before therapy, BW was estimated independently by 2 physicians, 2 emergency nurses, and a neuroradiological technical assistant. Patients were weighed, and anthropometric measurements for BW approximation were taken. Dosing errors were assessed. Clinical outcome was evaluated at 90 days.
Results: Of 109 patients, 55 (50.5%) were unable to provide information on their BW. Of those, 11 (20%) were accompanied by relatives able to give BW information. For all patients, estimation errors rates ranged from 20.8% (patient's own estimation) up to 38.2% (treating physician) and 42.2% (emergency nurse). Finally, 29 patients received an Alteplase dosage diverging >10% from the optimal dose. Twelve were under- and 17 overdosed. Underdosage was an independent predictor for worse outcome in multivariate analysis.
Conclusions: Our study shows that reliable BW data are missing for a majority of intravenous thrombolysis patients. Measuring BW before administering Alteplase remains challenging. Given dosing errors in one-third of patients and the observed impact on outcome, standardized weighing before thrombolysis should be considered. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01006434.