Copeptin is a stress hormone released in an equal proportion to vasopressin (AVP), and serves a surrogate marker for the hypothalamo-pituitary-adrenal axis. Prior literature has suggested that Copeptin is a promising prognostic biomarker in vascular diseases such as MI, CHF and ischemic stroke/TIA. However, the prognostic value of Copeptin in regard to long-term risk of vascular events after TIA and stroke remains uncertain.
In this issue of Stroke, Griesenegger et al. present a longitudinal population-based study with a mean follow–up of 5.7 years, to determine whether Copeptin levels could predict the long-term risk of vascular events in patients with TIA or ischemic stroke. The authors also contrasted Copeptin level amongst different etiological subtypes of stroke/TIA.
Of 92,728 individuals in the Oxford Vascular Study, 1076 eligible patients (mean age 75) with TIA, minor and major ischemic stroke recruited from 2002-2007, were included. Copeptin level was obtained at baseline (median time to sampling 5 days) and repeated in 384 patients after one year. 
After about 6000 patient-years of follow-up, the cox regression analysis including age, sex, hypertension, diabetes, previous MI, stroke, peripheral vascular disease, smoking, CHF, atrial fibrillation, and treatment with antiplatelets, statins or antihypertensive agents, showed that Copeptin significantly predicted subsequent vascular events (HR 1.47), recurrent ischemic stroke (HR 1.22), vascular death (HR 1.85) and all cause death (HR 1.75). The predictive value of Copeptin was greatest following a cardioembolic cerebrovascular event. Moreover, Copeptin outperformed other circulating biomarkers of thrombosis, inflammation and neuronal/myocardial injury within this population.
Inclusion of Copeptin into a model containing the aforementioned vascular risk factors improved the model’s predictive ability for recurrent vascular events, vascular death, death and recurrent stroke by 32%, 55%, 66% and 16%, respectively.
Overall, Copeptin seems to be a promising biomarker in risk stratification after ischemic stroke and TIA, particularly in patients with cardiogenic strokes/TIA. One of the main limitations of the study is the lack of adjustment for other possible confounding factors, such as indices of cardiac function. Therefore, further validation of these findings with the inclusion of cardiac markers is warranted.
