Stroke: A Leading Global Threat

In order to support evidence-based healthcare and resource allocation, a team of researchers recently released updated national, regional, and worldwide estimates of stroke burden and related risks from 1990 to 2021 in The Lancet Neurology.

Context
The prevalence of cardiovascular illness, including stroke, than doubled from 271 million in 1990 to 523 million in 2019, according to the Global Burden of illness (GBD) research.

Cardiovascular mortality rates decreased in the late 20th century, but this progress has halted, and since 2010, mortality rates have been rising in several nations, such as Mexico, the United Kingdom (UK), and the United States of America (USA).

Alongside a rise in risk factors like obesity and hypertension, the incidence of strokes among people under 55 has also increased. To monitor trends, assess therapies, and develop global health plans for stroke management and prevention, further research is necessary.

About the study
In line with earlier projections, the GBD 2021 study on stroke burden and risk variables used well-established methodology.

Three forms of stroke were identified using the World Health Organization’s (WHO) clinical criteria: subarachnoid hemorrhage (bleeding between the brain and its covering), intracerebral hemorrhage (bleeding inside the brain), and ischemic stroke (blocked blood flow to the brain).

To ensure accurate modeling, separate models were created for each type of stroke using vital registration and surveillance data. DisMod-MR 2.1, a Bayesian program that takes into account a number of illness factors, was used to model the incidence and prevalence of strokes.

Cause of Death Ensemble modeling (CODEm) was used to calculate death estimates. Numerous sources provided data for the analysis, such as verbal autopsy, vital registration, and risk factor exposure data.

Population attributable fractions (PAFs) of disability-adjusted life years (DALYs) were computed to evaluate the burden of stroke related to 23 risk variables. These variables were divided into four groups: metabolic, behavioral, nutritional, and environmental hazards.

In order to account for mediation effects in the final computation, the analysis additionally took into account interactions between risk factors.

The study estimated the possible reduction in stroke burden if exposure to risk factors had been at optimal levels by pooling relative risk data using meta-regression techniques. This thorough method made it possible to stratify estimates by sociodemographic index (SDI), age, sex, and area.

Conclusions
In summary, among non-communicable conditions, stroke ranked third in terms of DALYs and second in terms of death worldwide in 2021. Intracerebral hemorrhage was almost twice as common in LMICs as in high-income nations, and the burden of stroke was disproportionately higher in LMICs and areas with poorer SDI.

The greater prevalence and worse management of hypertension in LMICs are probably the causes of this discrepancy. Age-standardized stroke rates have decreased globally since 1990, but since 2015, Southeast Asia, East Asia, and Oceania have seen increases in incidence, prevalence, and DALYs.

For more information: Global, regional, and national burden of stroke and its risk factors, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021, The Lancet Neurology, doi: https://doi.org/10.1016/S1474-4422(24)00369-7