Cardiometabolic biomarker domains and functional ageing: Cross-cohort evidence for incident mobility limitation.

BACKGROUND: Cardiometabolic dysfunction may contribute to functional ageing, but whether biomarker domains show consistent associations with mobility limitation across ageing populations remains unclear. We examined cardiometabolic biomarkers and a simple biomarker-burden score for incident mobility limitation in three longitudinal ageing cohorts.

METHODS: We used data from the English Longitudinal Study of Ageing, China Health and Retirement Longitudinal Study, and Health and Retirement Study. Participants with baseline mobility limitation were excluded. Incident mobility limitation was defined as new difficulty in at least one mobility-related physical functioning item at follow-up. Candidate markers represented blood pressure, glycaemic, lipid, and inflammatory domains. Associations were estimated using modified Poisson regression. An ELSA-derived score based on systolic blood pressure, HbA1c, HDL cholesterol, and log-transformed C-reactive protein was evaluated in CHARLS and HRS. Sensitivity analyses examined stricter mobility outcomes, objective performance, medication adjustment, and multiple imputation.

RESULTS: The analysis included 13,650 participants. Incident mobility limitation occurred in 292/1291 ELSA participants, 2842/6861 CHARLS participants, and 2160/5498 HRS participants. Glycaemic markers showed the most consistent associations. The score was associated with incident mobility limitation in ELSA, CHARLS, and HRS, with adjusted risk ratios of 1.31, 1.07, and 1.08 per 1-SD increase, respectively. Associations were supported by stricter mobility definitions and multiple imputation, although objective performance and medication-related analyses were heterogeneous. External discrimination was modest.

CONCLUSIONS: Cardiometabolic biomarker domains, particularly glycaemic dysfunction, were reproducibly associated with incident mobility limitation. A simple biomarker-burden score captured a relevant but incomplete component of functional ageing risk.