Predictive value of the waist-to-height ratio and HbA1c product for incident stroke: a stratified analysis by blood pressure status

BACKGROUND: To investigate the association between the product of waist-to-height ratio and glycated hemoglobin (WHH) and the risk of incident stroke, and to examine whether this association varies by hypertension status. METHODS: A total of 7 987 participants without a history of stroke at baseline (2011) were enrolled from the China Health and Retirement Longitudinal Study (CHARLS). WHH was used as the exposure variable. Follow-up was conducted until 2020, with incident stroke confirmed during follow-up surveys in 2013, 2015, 2018, and 2020. Multiple imputation was applied to handle missing data. Cox proportional hazards models and restricted cubic spline (RCS) curves were used to analyze the association between WHH and stroke, with stratification by hypertension status to assess heterogeneity. In addition, Time-dependent ROC were used to evaluate the predictive ability of WHH for stroke, and sensitivity analyses were performed to verify the robustness of the results. RESULTS: During the 9-year follow-up period, 863 participants (10.81%) developed stroke. WHH was identified as an independent risk factor for stroke. Stratified analysis showed that the association between WHH and stroke was stronger among normotensive individuals (HR=1.53, 95% CI: 1.24-1.88, P < 0.001), whereas it was attenuated among those with hypertension (HR=1.18, 95% CI: 1.03-1.36, P = 0.019). Moreover, compared with waist-to-height ratio (WHtR) or glycated hemoglobin (HbA1c) alone, WHH demonstrated superior predictive performance for stroke. CONCLUSIONS: WHH is an important predictor of incident stroke in middle-aged and older adults, with particularly strong predictive value among individuals with normal blood pressure.