The Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SONIA) Trial
JoanMartí-Fàbregas, Department of Neurology, Hospital de la Santa Creu i Sant Pau, Avda. Sant Antoni Maria Claret, 167. 08025 Barcelona, Spainjmarti@santpau.es
Sergi Martínez-Ramírez, Josep-Lluis Martí-Vilalta
Submitted November 25, 2007
We congratulate Feldmann et al. on their study concerning the Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SONIA) trial. [1] Although the negative predictive value (NPV) for the Magnetic Resonance Angiography (MRA) and Transcranial Doppler (TCD) were high (91% for MRA and 86% for TCD), the positive predictive value (PPV) for both tests were disappointingly low (59% and 36%, respectively).
We conducted a trial comparing aspirin to anticoagulants in the prevention of vascular events in patients with symptomatic stenosis of the middle cerebral artery (MCA). [2] We included patients only when two of the three non-invasive (MRA, TCD or CT- angiography) tests indicated the diagnosis of MCA stenosis greater than 50%. We think it would be beneficial to re-analyze the SONIA data comparing the diagnostic results of MRA and TCD with conventional angiography when both non-invasive tests are abnormal (both of them instead of anyone of them). We believe this would provide higher and more reliable PPV.
In addition, when the tests are performed is important. In our study, to minimize the risk of misdiagnosing a MCA stenosis instead of a recanalizing embolus, we accepted the abnormal results only when they were obtained a minimum of seven days after the onset of stroke.
We would like to know when the tests of the SONIA study were obtained. If the results were obtained within a few days after stroke, this could be a source of misclassification. To improve the PPV, it seems prudent to exclude patients in whom the tests were obtained within the first week after the onset of symptoms.
References
1. Feldmann E, Wilterdink JL, Kosinski A, et al. The stroke outcomes and neuroimaging of intracranial atherosclerosis (sonia) trial. Neurology 2007;68:2099-2106.
2. Marti-Fabregas J, Cocho D, Marti-Vilalta JL, et al. Aspirin or anticoagulants in stenosis of the middle cerebral artery: A randomized trial. Cerebrovasc Dis. 2006;22:162-169.
Disclosure: The authors report no conflicts of interest.
We congratulate Feldmann et al. on their study concerning the Stroke Outcomes and Neuroimaging of Intracranial Atherosclerosis (SONIA) trial. [1] Although the negative predictive value (NPV) for the Magnetic Resonance Angiography (MRA) and Transcranial Doppler (TCD) were high (91% for MRA and 86% for TCD), the positive predictive value (PPV) for both tests were disappointingly low (59% and 36%, respectively).
We conducted a trial comparing aspirin to anticoagulants in the prevention of vascular events in patients with symptomatic stenosis of the middle cerebral artery (MCA). [2] We included patients only when two of the three non-invasive (MRA, TCD or CT- angiography) tests indicated the diagnosis of MCA stenosis greater than 50%. We think it would be beneficial to re-analyze the SONIA data comparing the diagnostic results of MRA and TCD with conventional angiography when both non-invasive tests are abnormal (both of them instead of anyone of them). We believe this would provide higher and more reliable PPV.
In addition, when the tests are performed is important. In our study, to minimize the risk of misdiagnosing a MCA stenosis instead of a recanalizing embolus, we accepted the abnormal results only when they were obtained a minimum of seven days after the onset of stroke.
We would like to know when the tests of the SONIA study were obtained. If the results were obtained within a few days after stroke, this could be a source of misclassification. To improve the PPV, it seems prudent to exclude patients in whom the tests were obtained within the first week after the onset of symptoms.
References
1. Feldmann E, Wilterdink JL, Kosinski A, et al. The stroke outcomes and neuroimaging of intracranial atherosclerosis (sonia) trial. Neurology 2007;68:2099-2106.
2. Marti-Fabregas J, Cocho D, Marti-Vilalta JL, et al. Aspirin or anticoagulants in stenosis of the middle cerebral artery: A randomized trial. Cerebrovasc Dis. 2006;22:162-169.
Disclosure: The authors report no conflicts of interest.