Background and Purpose - Many patients with transient ischemic attack (TIA) or minor stroke present to medical attention after a delay of several days or weeks, at which time it may be more difficult to obtain a clear...Background and Purpose - Many patients with transient ischemic attack (TIA) or minor stroke present to medical attention after a delay of several days or weeks, at which time it may be more difficult to obtain a clear history and clinical signs may have resolved. Because ischemic lesions on diffusion- weighted MRI (DWI) often persist for several weeks, we hypothesized that adding DWI to a standard protocol with T2- weighted imaging might be useful in the management of patients presenting late. Methods - We studied consecutive patients with TIA or minor stroke presenting ≥ 3 days after the event. Two independent observers recorded the presence or absence of recent ischemic lesions on 2 different occasions, first with the T2 scan only, and second with T2 and DWI. Each time, with the aid of a written clinical summary, the observers recorded their diagnosis and proposed management. Results - 300 patients (159 men) were scanned at a median of 17 (interquartile range=10 to 23) days after symptom onset. DWI showed a high signal lesion in 114/164 (70% ) minor strokes versus 17/136 (13% ) TIAs (P < 0.0001). The presence of high- signal lesions on DWI decreased nonlinearly with time since symptom onset (F < 0.0001) and increased with National Institutes of Health Stroke Score (P=0.038) and with age (P=0- 01). In 90/206 (43.7% ) patients with 1 or multiple lesions on T2, DWI helped to clarify whether these were related to a recent ischemic event (79 [48% Abstract: strokes; 11 [31% Abstract:- TIAs). Compared with T2 alone, DWI provided additional information in 108 (36% ) patients (91 [56% Abstract: strokes and 17 [13% Abstract: TIAs), such as clarification of clinical diagnosis (18 patients, 6% ) or vascular territory (28 patients, 93% ), which was considered likely to influence management in 42 (14% )- patients (32 [19% Abstract: strokes; 10 [7.4% Abstract: TIAs). Conclusions - The clinically useful information available from DWI provides a further justification for an MRI- based imaging protocol in patients with subacute TIA or minor stroke.展开更多
Clinicians often have to make treatment decisions based on the likelihood that an individual patient will benefit. In this article we consider the relevance of relative and absolute risk reductions, and draw attention...Clinicians often have to make treatment decisions based on the likelihood that an individual patient will benefit. In this article we consider the relevance of relative and absolute risk reductions, and draw attention to the importance of expressing the results of trials and subgroup analyses in terms of absolute risk. We describe the limitations of univariate subgroup analysis in situations in which there are several determinants of treatment effect, and review the potential for targeting treatments with risk models, especially when benefit is probably going to be dependent on the absolute risk of adverse outcomes with or without treatment. The ability to systematically take into account the characteristics of an individual patient and their interactions, to consider the risks and benefits of interventions separately if needed, and to provide patients with person alised estimates of their likelihood of benefit is shown using the example of endarterectomy for symptomatic carotid stenosis.展开更多
文摘Background and Purpose - Many patients with transient ischemic attack (TIA) or minor stroke present to medical attention after a delay of several days or weeks, at which time it may be more difficult to obtain a clear history and clinical signs may have resolved. Because ischemic lesions on diffusion- weighted MRI (DWI) often persist for several weeks, we hypothesized that adding DWI to a standard protocol with T2- weighted imaging might be useful in the management of patients presenting late. Methods - We studied consecutive patients with TIA or minor stroke presenting ≥ 3 days after the event. Two independent observers recorded the presence or absence of recent ischemic lesions on 2 different occasions, first with the T2 scan only, and second with T2 and DWI. Each time, with the aid of a written clinical summary, the observers recorded their diagnosis and proposed management. Results - 300 patients (159 men) were scanned at a median of 17 (interquartile range=10 to 23) days after symptom onset. DWI showed a high signal lesion in 114/164 (70% ) minor strokes versus 17/136 (13% ) TIAs (P < 0.0001). The presence of high- signal lesions on DWI decreased nonlinearly with time since symptom onset (F < 0.0001) and increased with National Institutes of Health Stroke Score (P=0.038) and with age (P=0- 01). In 90/206 (43.7% ) patients with 1 or multiple lesions on T2, DWI helped to clarify whether these were related to a recent ischemic event (79 [48% Abstract: strokes; 11 [31% Abstract:- TIAs). Compared with T2 alone, DWI provided additional information in 108 (36% ) patients (91 [56% Abstract: strokes and 17 [13% Abstract: TIAs), such as clarification of clinical diagnosis (18 patients, 6% ) or vascular territory (28 patients, 93% ), which was considered likely to influence management in 42 (14% )- patients (32 [19% Abstract: strokes; 10 [7.4% Abstract: TIAs). Conclusions - The clinically useful information available from DWI provides a further justification for an MRI- based imaging protocol in patients with subacute TIA or minor stroke.
文摘Clinicians often have to make treatment decisions based on the likelihood that an individual patient will benefit. In this article we consider the relevance of relative and absolute risk reductions, and draw attention to the importance of expressing the results of trials and subgroup analyses in terms of absolute risk. We describe the limitations of univariate subgroup analysis in situations in which there are several determinants of treatment effect, and review the potential for targeting treatments with risk models, especially when benefit is probably going to be dependent on the absolute risk of adverse outcomes with or without treatment. The ability to systematically take into account the characteristics of an individual patient and their interactions, to consider the risks and benefits of interventions separately if needed, and to provide patients with person alised estimates of their likelihood of benefit is shown using the example of endarterectomy for symptomatic carotid stenosis.
