Systemic proportional pulse index is associated with incident probable dementia: a post-hoc analysis of the SPRINT-MIND trial in the United States.

BACKGROUND: Pulse pressure (PP) is associated with cognitive decline but does not account for inter-individual differences in body size that may influence vascular load. We evaluated whether the systemic proportional pulse index (SPI), a body size-indexed pulsatile measure, is associated with incident probable dementia in the Systolic Blood Pressure Intervention Trial Memory and Cognition in Decreased Hypertension (SPRINT-MIND). METHODS: We conducted a post-hoc analysis of SPRINT-MIND participants with complete baseline blood pressure and anthropometric data. SPI was calculated as PP indexed to the body surface area. The primary outcome was incident probable dementia adjudicated using standardized SPRINT-MIND protocols. Cox proportional hazards models evaluated associations between SPI and dementia after adjustment for demographic and clinical covariates. Incremental prognostic value was assessed using Harrell's C-index and Akaike Information Criterion. RESULTS: Among 6,070 participants (mean age, 63.2±6.0 years; 65.7% male), 110 (1.8%) developed probable dementia during follow-up. Higher SPI was independently associated with increased dementia risk in models adjusting for PP and body surface area (p=0.031). Participants in the highest SPI quartile had greater risk compared with the lowest quartile (hazard ratio, 2.36; 95% confidence interval, 1.27-4.39). Addition of SPI modestly improved model discrimination and fit beyond PP alone. CONCLUSIONS: SPI is independently associated with incident probable dementia and provides modest incremental prognostic information beyond standard clinical factors and PP, suggesting that incorporating body size into assessment of pulsatile load may refine vascular risk stratification for cognitive outcomes, pending external validation.