Symptomatic carotid stenosis risk prediction

Fig. 14.2. An external validation of the model detailed in Table 14.2 for the five-year risk of stroke on medical treatment in an independent randomized trial of endarterectomy versus medical treatment for symptomatic carotid stenosis (Rothwell et ai. 2005). Predicted risk of stroke on medical treatment is plotted against the observed risk of stroke in patients randomized to medical treatment in the trial (squares) and against the observed operative risk of stroke and death in patients randomized to surgical treatment (diamonds). Groups are quintiles of predicted risk.

Prediction of risk using models requires a computer, a pocket calculator with an exponential function or internet-access (the ECST model can be found at www.stroke. ox.ac.uk). As an alternative, a simplified risk score based on the hazard ratios derived from the relevant risk model can be derived. Table 27.3 shows a score for the five-year risk of stroke on medical treatment in patients with recently symptomatic carotid stenosis derived from the ECST model. As is shown in the example, the total risk score is the product of the scores for each risk factor. Fig. 27.7 shows a plot of the total risk score against the five-year predicted risk of ipsilateral carotid territory ischemic stroke derived from the full model and is used as a nomogram for the conversion of the score into a risk prediction. 

Table 27.3. A predictive model for five-year risk of ipsilatera in patients with recently symptomatic carotid stenosis ...

Markus H, Mac Kinnon A. Asymptomatic embolization detected by Doppler ultrasound predicts stroke risk in symptomatic carotid artery stenosis. Stroke 2005 36 971-975. 

The risk models described above were derived and validated in populations with a low prevalence of symptomatic carotid disease and, therefore, did not include the degree of carotid stenosis. Given the importance of carotid stenosis in determining the risk of stroke in patients with recently symptomatic carotid disease, models are required for use in this specific clinical situation. This is particularly important because the treatment for carotid stenosis, carotid endarterectomy, itself has important risks associated with it Risk models have, therefore, been derived to predict the risks associated with medical and surgical treatment in patients with carotid stenosis in order to itrform decision making surrounding treatment options. 

Asymptomatic embolization detected by Doppler ultrasound predicts stroke risk in symptomatic carotid artery stenosis. 

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