Stroke recurrence remains a major threat to survivors, but encouraging data suggest the risk may be a lot lower than previously estimated, and decreasing with better secondary prevention, Danish researchers say.

A study of 118,747 patients with first-time stroke between 2004 and 2018 found those with initial ischaemic stroke (IS) had one- and 10-year recurrence rates of 4% and 13%, while intracerebral haemorrhage patients’ (ICH) recurrence risks were 3% and 12%, respectively.

Older patients, males and those with milder versus more severe stroke or higher Essen scores were at greater risk of IS recurrence, though age and Essen score had little effect on ICH risk.

Both patient types faced higher all-cause mortality risk after recurrent versus first-time stroke, with one- and 10-year rates being 25% and 70% versus 17% and 56% for IS, and 31% and 75% versus 37% and 70% for ICH, respectively.

Fortunately, they also saw one-year recurrence risk drop by 0.3% and 0.6% in IS and ICH, respectively, from 2004–2006 to 2016–2018 (subdistribution hazard ratios: 0.75 and 0.59).

“The overarching implication of our study is that recurrence continues to be a major threat to stroke survivors, even in a contemporary population treated in accordance with guidelines on secondary prevention regarding the use of statin, antiplatelet, and anticoagulant therapy”, Nils Skajaa and the team at Aarhus University Department of Epidemiology wrote in Neurology.

Despite the “substantial” recurrence risk, the results were “encouraging” an accompanying editorial noted.

Earlier studies have pegged first-time overall stroke recurrence risks at 11% at one year and 39% at 10 years — much higher than the risks reported in the current study. These results were in line with more recent studies, however, which put one-year risk at 5–8%, the authors said.

Regarding increasing mortality after recurrent stroke, Mr Skajaa and team posited that additional neurological deficit may lead to “increased susceptibility to some infections (e.g. pneumonia, urinary tract infections and septicaemia) and other complications and thereby a worse prognosis”, though the underlying mechanisms need to be confirmed.

Nonetheless, the decreasing one-year recurrence rates were positive and could reflect improving effectiveness and implementation of secondary prevention strategies including dual antiplatelet therapy and increased use of interventions such as thrombectomy over the study period, both the study and editorial read.

“The temporal trends described in this study indicate an improved prognosis of stroke, which is in line with reports that dementia risk after stroke as well as age-standardised incidence and mortality of stroke has declined over time,” the editorial authors said

The findings could help clinicians give more accurate recurrence and mortality prognoses to first-time stroke patients and their families and support more targeted intervention, they suggested.

Future research should “focus on novel strategies to improve secondary prevention and reduce morbidity and mortality from stroke” and update recurrence estimates in diverse populations, they concluded.