ESJ Comment: Young ischaemic stroke incidence and demographic characteristics – The Norwegian stroke in the young study – A three-generation research program.

Author: Dr Nicolas Martinez-Majander, Department of Neurology, Helsinki University Hospital, Finland.

Original Article: Nawaz B, Eide GE, Fromm A et al, 2019. Young ischaemic stroke incidence and demographic characteristics – The Norwegian stroke in the young study – A three-generation research program.

The impact of stroke in the young is more extensive than in the elderly, affecting the family, social life, and working ability for years after the event. Due to yet largely unstudied reasons, the incidence of ischaemic stroke at younger ages has been increasing for several decades. Patients with stroke at younger ages have a considerably wider spectrum of risk factors compared to patients at older ages. However, recent studies showed that the contribution of traditional stroke risk factors to young-onset stroke was more than earlier reported. Furthermore, the absolute risk of recurrent stroke after the first year is 1-2% per year, and the long-term mortality about 4-fold compared to background population. Given the impact of young stroke, new data on the topic are very important.

In this paper published in the ESJ, Nawaz and colleagues reported results from the Norwegian stroke in the young study (NOR-SYS), a hospital- and population-based, single center, three-generation, prospective long-term observational study. The study protocol has been published more in detail previously. Briefly, patients aged 15-60 with an imaging-positive ischaemic stroke from the Haukeland University Hospital area were included in the study and examined by operating procedures, including a detailed ultrasound protocol. In addition, partners, ex-partners, adult offspring ≥18 years, patients’ parents, and partners’ parents were also included. Enrollment period was from September 2010 to August 2015. Patients with post-traumatic stroke, venous stroke, procedure-related stroke, serious co-morbidity, or otherwise limited cooperation were excluded.

Findings

Of a total of 385 patients and their family members, the main findings were as follows:

  1. The annual incidence rate for young and middle-aged ischaemic stroke was 25.0-34.7 per 100,000 with a mean annual incidence rate of 30.2 per 100,000, which was higher than reported in previous studies. However, direct comparison between studies is difficult due to different catchment areas. Furthermore, in younger patients aged 15-49 years, the annual incidence was lower than in patients aged 40-60 years (8.5-20.0 vs. 78.4-100.0 per 100,000).
  2. Incidence was higher in men, except in very young women aged <25 years. As the authors discussed, this might be due to an increased prevalence of well-documented risk factors in men, in contrast to sex-specific risk factors in very young women (e.g. pregnancy, puerperium, contraceptives, migraine with aura and autoimmune disorders).
  3. Education and work status prior to index stroke were high in young stroke patients and did not differ between sexes. However, more men were working full-time (80.3% vs. 52.9%).
  4. Finally, the participation rate was excellent for patients and was also good amongst the first grade family members, which suggest that NOR-SYS may provide valuable information of stroke inheritance in future analyses.

As the authors concluded, NOR-SYS is the first detailed family study of young ischaemic stroke and may also provide useful information about the social-economic burden of stroke at working ages. We are looking forward to reading also results from their future analyses!

References

Nawaz B, Eide GE, Fromm A et al, 2019. Young ischaemic stroke incidence and demographic characteristics – The Norwegian stroke in the young study – A three-generation research program. European Stroke Journal.

Fromm A, Thomassen L, Naess H, et al. The Norwegian Stroke in the Young Study (NOR-SYS): rationale and design. BMC Neurol 2