Biological age may be more accurate than chronological age in determining chronic health outcomes. However, few studies have shown the association between biological age and acute ischemic stroke (AIS). In this study we showed the association between phenotypic age (PhenoAge) or accelerated aging and severity and disability in patients with AIS. Retrospective study. 936 patients with AIS during January 2019 to July 2021 and 512 patients during June 2022 to July 2023 for a validation. Stroke severity was evaluated based on the National Institute of Health stroke scale (NIHSS) questionnaire scale. Disability was evaluated by modified Rankin Scale. PhenoAge was calculated based on chronological age and 9 clinical chemistry biomarkers. Logistic regression analyses were applied to estimate the relationship between PhenoAge and the severity and disability. PhenoAge (odds ratio [OR] = 1.03, 95% confidence interval [CI]: 1.0-1.04, for NIHSS ≥ 5; OR = 1.05, 95%CI: 1.03-1.07, for NIHSS ≥ 10) was independently associated with stroke severity. The probability of NIHSS ≥ 5 or NIHSS ≥ 10 was significantly increased in individuals with accelerated ageing versus individuals with no accelerated aging (age gap: OR = 1.79, 95%CI: 1.18-2.72; OR = 3.53, 95%CI: 1.60-7.77; phenotypically older vs. phenotypically younger: OR = 2.01, 95%CI: 1.21-3.35; OR = 3.69, 95%CI: 1.36-10.0). Similar trends was observed when accelerated aging was defined by residual discrepancies between PhenoAge and chronological age (OR = 1.02, 95%CI: 1.01-1.04, for NIHSS ≥ 5; OR = 1.05, 95%CI: 1.02-1.08, for NIHSS ≥ 10). The area under the curve of PhenoAge was higher than that of chronological age in identifying patients with NIHSS ≥ 5 (0.66, 95%CI:0.62-0.70 vs. 0.61, 95%CI: 0.58-0.65, p < 0.01) and NIHSS ≥ 10 (0.69, 95%CI:0.60-0.77 vs. 0.63, 95%CI: 0.55-0.72, p = 0.05). The probability of severe disability was significantly increased in individuals with accelerated aging versus individuals with no accelerated aging (age gap: OR = 2.87, 95%CI: 1.09-7.53; phenotypically older vs. phenotypically younger: 4.88 (1.20-19.88). Similar results were observed in the validation population. PhenoAge or accelerated aging is associated with stroke severity and disability even after adjusting for chronological age.

Background: Body mass index (BMI) could not exactly reflect body fat distribution. Body Roundness Index (BRI) may be a better marker reflecting the ratio of total body fat to visceral fat. This study aimed to show the association between BRI and intramuscular fat infiltration (IMFI), and compare the ability of the BRI and BMI to predict IMFI in general populations. Methods: The assessment of IMFI was conducted via both computed tomography (CT) and magnetic resonance imaging (MRI). In the CT cohort, IMFI was defined as CT attenuation < 37.5 Hounsfield Unit. In the MRI cohort, the IMFI was evaluated by fat fraction. Those with a fat fraction higher than the third quartile of the overall population were defined as the IMFI. Logistic regression analysis, Spearman’s correlation, stratified analysis, and receiver operating characteristic (ROC) curve analysis were performed to investigate the associations between BMI, BRI and the IMFI. Results: A total of 1,268 participants were included in the CT cohort and 198 subjects in MRI cohort. The subjects with high BRI (≥5.5) had higher prevalence of IMFI than those with BRI < 5.5 (67.3% vs. 25.4%, p < 0.001). BRI and BMI was both associated with an increased risk of IMFI in CT cohort [odds ratio (OR) = 1.96, 95%confidence interval (CI): 1.55–2.49; OR = 1.20, 95%CI: 1.13–1.28]. Similar trends were observed between high and low BRI and BMI quartiles groups. Spearman’s correlation revealed that the BRI was associated with muscle density, muscle fat fraction and handgrip strength in both men and women. The ROC curve revealed that the BRI had a better ability to predict the risk of IMFI than BMI ( p < 0.05) in both CT and MRI cohort. Conclusion: Compared with BMI, the BRI is a better index to evaluate the IMFI, especially in the female population.