Stroke incidence in the young: evidence from a Norwegian register study

Abstract

Introduction: While there is a general agreement that stroke incidence among the elderly is declining in the developed world, there is a concern that it may be increasing among the young. The present study investigates this issue for the Norwegian population for the years 2010–2015. Cerebrovascular accidents (CVAs) for patients younger than 55 years were identified through the Norwegian Patient Registry and the Norwegian Cause-of-death Registry. Methods: Negative binomial regression modelling was used to estimate temporal trends in the CVA incidence rates for the young, aged 15–54, with 10-year sub-intervals, and for children below the age of 18. The main outcomes were CVA incidence per 100,000 person-years at risk (PY), 30-day stroke mortality per 100,000 PY, and 30-day case-fatality rates. Results: The analysis showed a negative and non-significant temporal trend in the CVA incidence (p= 0.052) as well as for 30-day mortality (p= 0.074) for the age group 15–54. Overall, the inclusion of an interaction for age in the bracket 45–54 suggested that any temporal decline is restricted to this age bracket. The analyses of the 10-year age brackets 15–24, 25–34, and 34–45, provided evidence neither for an increase, nor for a decrease, in incidence. Among the children, the estimated temporal coefficients were positive, but non-significant, consistent with a stationary trend. Conclusion: Weak statistical evidence was found for a decline in CVA incidence and for overall stroke 30-day case fatality for 15–54 year olds, but the decline was significant only for the 45–54 age band. All results considered, the study suggests a stationary or decreasing temporal trend in CVA incidence and stroke fatality for children (0–18) and young (15–54) in Norway. Even larger data sets are needed to estimate these temporal trends accurately.