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 ([Formula: see text]) as well as for 30-day mortality ([Formula: see text]) 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.
Keywords: Case fatality; Cerebrovascular accident; Epidemiology; Regression modelling; Stroke incidence.