ImportanceUncertainty persists regarding the independent association of general and central adiposity with major stroke types.ObjectiveTo determine the independent associations of general and central adiposity with risk of ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage.Design, Setting, and ParticipantsBetween 2006 and 2010, adults without prior stroke at recruitment in England, Scotland, and Wales were recruited into the UK Biobank prospective cohort study and were followed up through linkage with electronic medical records. Data were analyzed from September 2021 to September 2022.ExposuresGeneral adiposity (body mass index [BMI] calculated as weight in kilograms divided by height in meters squared) and central adiposity (waist circumference).Main Outcomes and MeasuresIncident ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage as recorded through record linkage with electronic hospital records. Cox regression estimated adjusted hazard ratios (HRs) by stroke type.ResultsAmong 490 071 participants, the mean (SD) age was 56.5 (8.1) years, 267 579 (54.6%) were female, and 461 647 (94.2%) were White. During a median (IQR) of 12 (11.2-12.7) years follow-up, 7117 incident ischemic strokes, 1391 intracerebral hemorrhages, and 834 subarachnoid hemorrhages were identified. After mutual adjustment for waist circumference, BMI had no independent association with ischemic stroke (HR per 5-unit higher BMI, 1.04; 95% CI, 0.97-1.11), but was inversely associated with intracerebral hemorrhage (HR, 0.85; 95% CI, 0.74-0.96) and subarachnoid hemorrhage (HR, 0.82; 95% CI, 0.69-0.96). Waist circumference (adjusted for BMI) was positively associated with ischemic stroke (HR per 10-cm higher waist circumference, 1.19; 95% CI, 1.13-1.25) and intracerebral hemorrhage (HR, 1.17; 95% CI, 1.05-1.30), but was not associated with subarachnoid hemorrhage (HR, 1.07; 95% CI, 0.93-1.22).Conclusions and RelevanceIn this large-scale prospective study, the independent and contrasting associations of BMI and waist circumference with stroke types suggests the importance of considering body fat distribution to stroke risk. Waist circumference was positively associated with the risk of ischemic stroke and intracerebral hemorrhage, while BMI was inversely associated with the risk of subarachnoid hemorrhage and intracerebral hemorrhage. This study also suggests that some adverse correlate of low BMI may be associated with an increased risk of intracerebral hemorrhage and subarachnoid hemorrhage, which warrants further investigation.

Background Uncertainty persists about carotid intima–media thickness (CIMT) as a marker of subclinical atherosclerosis and the independent relevance of different measures of adiposity for CIMT. We assessed the independent relevance of general adiposity (body mass index), central adiposity (waist circumference), and body composition (fat mass index and fat‐free mass index) with CIMT among adults in the United Kingdom. Methods and Results Multivariable linear regression of cross‐sectional analyses of UK Biobank assessed the mean percentage difference in CIMT associated with equivalent differences in adiposity measures. To assess independent associations, body mass index and waist circumference were mutually adjusted, as were fat mass index and fat‐free mass index. Among 39 367 participants (mean [SD] age 64 [8] years, 52% female, 97% White), median (interquartile range) CIMT was 0.65 (0.14) mm in women and 0.69 (0.18) mm in men. All adiposity measures were linearly and positively associated with CIMT after adjusting for confounders. Fat‐free mass index was most strongly associated with CIMT after adjustment for fat mass index (% difference in CIMT: 1.23 [95% CI 0.93–1.53] women; 3.44 [3.01–3.86] men), while associations of fat mass index were attenuated after adjustment for fat‐free mass index (0.28 [−0.02, 0.58] women; −0.59 [−0.99, −0.18] men). After mutual adjustment, body mass index remained positively associated with CIMT, but waist circumference was completely attenuated. Conclusions Fat‐free mass index was the adiposity measure most strongly associated with CIMT, suggesting that CIMT may reflect vascular compensatory remodeling rather than atherosclerosis. Hence, screening for subclinical atherosclerosis should evaluate carotid plaques in addition to CIMT.