Several studies have reported varied risk of recurrent stroke after an index event. Traditional risk factors such as advanced age, diabetes, previous myocardial infarction, smoking, atrial fibrillation etc have been reported to predict stroke recurrence. Pennlert et al investigated long-term risk and predictors of recurrent stroke in Northern Sweden between 1995-2008 utilizing population based MONICA stroke incidence registry.
The authors identified 6700 patients of ischemic stroke (IS) or intracerebral hemorrhage (ICH) who survived for more than 28 days and were followed for a mean of 4 years (26,597 person-years). Authors report that overall cumulative stroke recurrence risk was 6%, 16% and 25% at 1, 5 and 10 years respectively. Interestingly, patients in the most recent cohort (2004-2008) had a 36% lower risk of recurrent stroke than patients in the first cohort (1995-1998) although among traditional risk factors only MI was less prevalent in the most recent cohort.
The study might underestimate the risk of recurrent stroke because recurrence during early phase (28 days) after qualifying event is not accounted for in this registry. Nevertheless, the results show declining risk of recurrent stroke over the last 2 decades which, in my opinion authors rightly point out, is representative of improved secondary prevention measures such as reduced smoking, aggressive lipid lowering measures and lifestyle modifications. Despite the declining rates, stroke recurrence remain an important clinical problem contributing significantly to morbidity and mortality.