Thomalla G, et al. - The researchers performed this study to examine the effect of informed consent on patient characteristics in a stroke thrombolysis trial. Compared to those with the capacity to give personal consent, patients recruited by proxy consent were older, had more severe strokes, and had a higher prevalence of aphasia. Across countries, variations in the manner of consent could influence trial results.

• For this study, the researchers examined the manner of obtaining informed consent in the first 1,005 patients from WAKE-UP, an investigator-initiated, randomized, placebo-controlled trial of MRI-based thrombolysis in stroke patients with unknown time of symptom onset running in 6 European countries.
• They compared patients providing informed consent by themselves with patients enrolled by proxy consent.
• They compared baseline clinical measures between groups.

• Informed consent was by proxy in 359 (35.7%) patients.
• Compared to patients providing informed consent by themselves, patients with proxy consent were older (median 71 vs 66 years, p < 0.0001) and had a higher frequency of arterial hypertension (58.2% vs 43.4%, p < 0.0001).
• They demonstrated higher scores on the NIH Stroke Scale (median 11 vs 5, p < 0.0001) and more frequently aphasia (73.7% vs 20.0%, p < 0.0001).
• Among countries, the rate of proxy consent varied (p < 0.0001), ranging from 77.1% in Spain to 1.2% in Denmark.