A biomarker-based biological age in UK Biobank: composition and prediction of mortality and hospital admissions.

BACKGROUND Chronological age is the strongest risk factor for most chronic diseases. Developing a biomarker-based age and understanding its most important contributing biomarkers may shed light on the effects of age on later life health and inform opportunities for disease prevention. METHODS A subpopulation of 141,254 individuals healthy at baseline were studied, from among 480,019 UK Biobank participants aged 40-70 recruited in 2006-2010, and followed up for 6-12 years via linked death and secondary care records. Principal components of 72 biomarkers measured at baseline were characterised and used to construct sex-specific composite biomarker ages using the Klemera Doubal method, which derived a weighted sum of biomarker principal components based on their linear associations with chronological age. Biomarker importance in the biomarker ages was assessed by the proportion of the variation in the biomarker ages that each explained. The proportions of the overall biomarker and chronological age effects on mortality and age-related hospital admissions explained by the biomarker ages were compared using likelihoods in Cox proportional hazard models. RESULTS Reduced lung function, kidney function, reaction time, insulin-like growth factor 1, hand grip strength and higher blood pressure were key contributors to the derived biomarker age in both men and women. The biomarker ages accounted for >65% and >84% of the apparent effect of age on mortality and hospital admissions for the healthy and whole populations, respectively, and significantly improved prediction of mortality (p<0.001) and hospital admissions (p<1×10 -10) over chronological age alone. CONCLUSIONS This study suggests that a broader, multi-system approach to research and prevention of diseases of ageing warrants consideration.