What is the clinical evidence from this study?

Study design: Cohort. Population: Stroke (n=132045). Intervention: Obesity (BMI ≥ 30 kg/m²) vs. Normal weight (BMI 18.5-24.9 kg/m²). Primary outcome: Incident stroke (ischemic strokes and intracerebral hemorrhages) (HR 1.36, 95% CI 1.27-1.45).

What does this research mean for the field?

Overweight and obesity independently increase the risk of stroke, even among younger and metabolically healthy individuals, with the combination of obesity and poor metabolic health conferring the highest risk. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

May 28, 2026Open Access

Associations of body mass index and metabolic health with stroke risk in a large prospective cohort with time updated covariates

Key Result

Obesity independently increased the risk of stroke compared to normal weight (HR 1.36), even after adjusting for metabolic health and other confounders.

Study Design

Type

Cohort (n=132,045)

Multicenter

Yes

Structured PICO

Do overweight, obesity, and poor metabolic health increase the risk of stroke in a general population?

Population

132,045 participants from the Northern Sweden Health and Disease Study

Intervention

Overweight, obesity, and poor metabolic health

Comparator

Normal weight and metabolically healthy individuals

Outcome

Stroke eventshard clinical

Overweight and obesity independently increase stroke risk, even among younger and metabolically healthy individuals, with the highest risk seen in those with combined obesity and poor metabolic health.

Main Result

Effect estimate: HR 1.36 (95% CI 1.27-1.45)

Limitations

Observational design and potential residual confounding by unmeasured factors such as genetics and diet
Metabolic health was modeled as a binary variable, which may oversimplify heterogeneous cardiometabolic risk profiles
BMI does not distinguish between fat and lean mass or account for fat distribution
Ischemic stroke and intracerebral hemorrhage were analyzed as a composite outcome without subtype-specific stratification
Findings pertain to a Swedish population and may not fully generalize to other settings

Abstract

Abstract The global prevalence of overweight and obesity is rising, and recent studies have established an independent contribution of adiposity to stroke risk. How the increased risk associated with adiposity relates to other factors including metabolic health is not fully understood. We analyzed 132,045 participants from the Northern Sweden Health and Disease Study with repeated health examinations (1985–2022). Stroke events were identified via national registers. Body mass index (BMI) was modeled as continuous (splines) and categorical (WHO definitions). Cox models with time-updated covariates estimated hazard ratios (HRs), and machine learning (XGBoost-AFT) assessed complex relationships. Over a median 20.2-year follow-up (2.67 million person-years), 7,493 strokes occurred. In fully adjusted models, overweight (HR: 1.14; 95% CI: 1.08–1.20) and obesity (HR: 1.36; 95% CI: 1.27–1.45) independently increased stroke risk versus normal weight. Poor metabolic health was also strongly associated (HR: 1.41 ; 95% CI: 1.34–1.49) with increased stroke risk. Combined obesity and poor metabolic health conferred the highest risk (HR: 1.79; 95% CI: 1.67–1.93). Age modified the association between higher BMI and stroke risk (p-interaction = 0.007), with stronger associations at younger ages. Machine learning confirmed the BMI-stroke risk pattern. In conclusion, overweight and obesity are associated with an independent stroke risk, even among younger and metabolically healthy individuals.

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