Methods
An
integer score was derived by Cox regression analysis on a
hospital-referred cohort of 3246 acute ischemic stroke patients from
Switzerland, and tested for external validity in three similar
independent cohorts from Athens (
n = 2495), Milan (
n = 1279), and Helsinki (
n = 714) by means of calibration and discrimination.
Results
In the derivation cohort, the recurrence rate was 7% (
n = 228/3246).
We developed a nine-point score comprising: previous stroke or
transient ischemic attack (1-point), stroke mechanism (small vessel
disease and unknown mechanism: 0-points; rare stroke mechanism:
3-points; other mechanisms: 1-point), pre-stroke antiplatelets
(1-point), active malignancy (2-points), chronic cerebrovascular lesions
on imaging (1-point) and absence of early ischemic changes on first
imaging (1-point). In the derivation cohort, the one-year risk of
re-stroke was 3.0% (95%CI 1.9–4.1) in 932 (29%) patients with a score
0–1, 7.2% (6.1–8.3) in 2038 (63%) with a score 2–4, and 19.2%
(14.6–23.9) in 276 (8%) with a score ≥ 5. The score calibrated well in
the Athens (recurrences = 208/2495), but not in the Helsinki
(recurrences = 15/714) or Milan (recurrences = 65/1279) cohorts. The AUC
was 0.67 in the derivation cohort, and 0.56, 0.70, and 0.63 in the
Athens, Helsinki, and Milan cohorts, respectively.
Conclusion
We
developed a score to predict one-year stroke recurrence risk in
patients with acute ischemic stroke. Since the score was not completely
validated when applied to external datasets where it displayed poor to
fair calibration and discrimination, additional efforts are required to
ameliorate our accuracy for predicting stroke recurrence, by better
refining this prognostic tool or developing new ones. Clinical and
radiological markers of established cerebrovascular disease and stroke
etiology were better predictors than the usual demographic vascular risk
factors.
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