Diverging Temporal Trends in Stroke Incidence in Younger vs Older People

Abstract

ImportanceOverall stroke incidence is falling in high-income countries, but data on time trends in incidence of young stroke (ie, stroke in individuals younger than 55 years) are conflicting. An age-specific divergence in incidence, with less favorable trends at younger vs older ages, might be a more consistent underlying finding across studies.ObjectiveTo compare temporal trends in incidence of stroke at younger vs older ages in high-income countries.Data SourcesPubMed and EMBASE were searched from inception to February 2022. One additional population-based study (Oxford Vascular Study) was also included.Study SelectionStudies reporting age-specific stroke incidence in high-income countries at more than 1 time point.Data Extraction and SynthesisFor all retrieved studies, 2 authors independently reviewed the full text against the inclusion criteria to establish their eligibility. Meta-analysis was performed with the inverse variance–weighted random-effects model. Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed.Main Outcomes and MeasuresThe main outcome was age-specific divergence (<55 vs ≥55 years) in temporal trends in stroke incidence (relative temporal rate ratio [RTTR]) in studies extending to at least 2000. RTTRs were calculated for each study and pooled by random-effects meta-analysis, with stratification by administrative vs prospective population-based methodology, sex, stroke subtype (ischemic vs intracerebral hemorrhage vs subarachnoid hemorrhage) and geographical region.ResultsAmong 50 studies in 20 countries, 26 (13 prospective population-based and 13 administrative studies) reported data allowing calculation of the RTTR for stroke incidence at younger vs older ages across 2 or more periods, the latest extending beyond 2000. Reported trends in absolute incidence of young individuals with stroke were heterogeneous, but all studies showed a less favorable trend in incidence at younger vs older ages (pooled RTTR = 1.57 [95% CI, 1.42-1.74]). The overall RTTR was consistent by stroke subtype (ischemic, 1.62 [95% CI, 1.44-1.83]; intracerebral hemorrhage, 1.32 [95% CI, 0.91-1.92]; subarachnoid hemorrhage, 1.54 [95% CI, 1.00-2.35]); and by sex (men, 1.46 [95% CI, 1.34-1.60]; women, 1.41 [95% CI, 1.28-1.55]) but was greater in studies reporting trends solely after 2000 (1.51 [95% CI, 1.30-1.70]) vs solely before (1.18 [95% CI, 1.12-1.24]) and was highest in population-based studies in which the most recent reported period of ascertainment started after 2010 (1.87 [95% CI, 1.55-2.27]).Conclusions and RelevanceTemporal trends in stroke incidence are diverging by age in high-income countries, with less favorable trends at younger vs older ages, highlighting the urgent need to better understand etiology and prevention of stroke at younger ages.

Association of Younger vs Older Ages With Changes in Incidence of Stroke and Other Vascular Events, 2002-2018

“…This finding of an absolute increase in incidence of young stroke validated UK hospital admission trends and was consistent with findings in the US . The relative divergence in incidence in younger vs older patients was also consistent with a linked systematic review in which analysis of all stroke incidence studies in the 21st century in high-income countries revealed less favorable trends in stroke incidence at younger ages vs older ages …”

“…Fourth, the current study results are based on a predominantly White population and might not be generalizable to other ethnic groups in whom stroke incidence might be higher . However, a similar magnitude of increase in incidence of young stroke was also found in the other population in this study, and no differences between ethnic groups were seen in the linked systematic review . Fifth, the diagnosis and management of acute myocardial infarction have changed over the last 20 years, including more sensitive assays for troponin over time and the introduction of primary percutaneous coronary intervention.…”

“…In light of these uncertainties, this population-based study aimed to determine the incidence of transient ischemic attack (TIA) and stroke and other vascular events in Oxfordshire, England, from 2002 to 2018, taking into account changes in diagnostic practices, control of traditional vascular risk factors, other exposures, lifestyle, and sex-specific causes of stroke. 9,10 In light of conflicting findings in previous studies, with stable or decreasing incidence of young stroke in some countries, [11][12][13] in a linked systematic review 14 the divergence in stroke incidence at younger vs older ages was quantified to determine whether a less favorable change in incidence at younger ages was a more consistent finding.…”

Disparities in stroke incidence over time by sex and age in Latin America and the Caribbean region: a systematic review and meta-analysis

“…The strengths of this systematic review include the availability of population-based studies, most of which met the suggested ' standard or advanced criteria for ideal stroke incidence studies ' and covered a long period 1,19 , with age and sex disaggregated data available. However, there are only a limited number of published reports from few countries, so our results should be interpreted with caution due to possible selection bias, the potential for unmeasured confounders, the lack of information on stroke severity/type and prevention strategies; and heterogeneity from the use of different methodology between older studies compared to more recent ones.…”

“…Disaggregated data of incidence rate (IR) were extracted from each article by sex and age (men: women, and age groups of <55 vs. ≥55 years and <45 vs. ≥45 years). The cut-off age of 55 was selected because it is the youngest age criterion used in previous epidemiological studies1 . When enough data were available, a cutoff age of 45 years was used, given current concerns regarding stroke in the young.…”