@article {1037, title = {A physiologic index of comorbidity: relationship to mortality and disability.}, journal = {J Gerontol A Biol Sci Med Sci}, volume = {63}, year = {2008}, month = {2008 Jun}, pages = {603-9}, abstract = {

BACKGROUND: In older adults, there is often substantial undiagnosed chronic disease detectable on noninvasive testing, not accounted for by most comorbidity indices. We developed a simple physiologic index of comorbidity by scoring five noninvasive tests across the full range of values. We examined the predictive validity of this index for mortality and disability.

METHODS: There were 2928 (mean age 74.5 years, 60\% women, 85\% white, and 15\% black) participants in the Cardiovascular Health Study (1992-1993) who had carotid ultrasound, pulmonary function testing, brain magnetic resonance scan, serum cystatin-C, and fasting glucose. These were combined into a single physiologic index of comorbid chronic disease on a scale of 0-10. Cox proportional hazard models were used to predict mortality, mobility limitation, and activities of daily living (ADL) difficulty after a maximum of 9 years.

RESULTS: The range of the physiologic index was quite broad, with very few individuals having total scores of either 0 or 10. Those with an index of 7-10 had a hazard ratio of 3.80 (95\% confidence interval, 2.82-5.13) for mortality compared to those with scores of 0-2, after adjustment for demographics, behavioral risk factors, and clinically diagnosed conditions. Associations with mobility limitation and ADL difficulty were also significant. The index explained about 40\% of the age effect on mortality risk.

CONCLUSION: Older adults with low levels of markers of chronic disease are rather rare but have remarkably good health outcomes. The ability of such an index to distinguish usual from low risk might provide an opportunity to better understand optimal health in old age.

}, keywords = {Activities of Daily Living, Aged, Comorbidity, Disabled Persons, Female, Health Status, Humans, Male, Mobility Limitation, Mortality, Predictive Value of Tests, Proportional Hazards Models}, issn = {1079-5006}, doi = {10.1093/gerona/63.6.603}, author = {Newman, Anne B and Boudreau, Robert M and Naydeck, Barbara L and Fried, Linda F and Harris, Tamara B} } @article {9640, title = {Plasma proteomic signature of human longevity.}, journal = {Aging Cell}, year = {2024}, month = {2024 Mar 05}, pages = {e14136}, abstract = {

The identification of protein targets that exhibit anti-aging clinical potential could inform interventions to lengthen the human health span. Most previous proteomics research has been focused on chronological age instead of longevity. We leveraged two large population-based prospective cohorts with long follow-ups to evaluate the proteomic signature of longevity defined by survival to 90 years of age. Plasma proteomics was measured using a SOMAscan assay in 3067 participants from the Cardiovascular Health Study (discovery cohort) and 4690 participants from the Age Gene/Environment Susceptibility-Reykjavik Study (replication cohort). Logistic regression identified 211 significant proteins in the CHS cohort using a Bonferroni-adjusted threshold, of which 168 were available in the replication cohort and 105 were replicated (corrected p value <0.05). The most significant proteins were GDF-15 and N-terminal pro-BNP in both cohorts. A parsimonious protein-based prediction model was built using 33 proteins selected by LASSO with 10-fold cross-validation and validated using 27 available proteins in the validation cohort. This protein model outperformed a basic model using traditional factors (demographics, height, weight, and smoking) by improving the AUC from 0.658 to 0.748 in the discovery cohort and from 0.755 to 0.802 in the validation cohort. We also found that the associations of 169 out of 211 proteins were partially mediated by physical and/or cognitive function. These findings could contribute to the identification of biomarkers and pathways of aging and potential therapeutic targets to delay aging and age-related diseases.

}, issn = {1474-9726}, doi = {10.1111/acel.14136}, author = {Liu, Xiaojuan and Axelsson, Gisli Thor and Newman, Anne B and Psaty, Bruce M and Boudreau, Robert M and Wu, Chenkai and Arnold, Alice M and Aspelund, Thor and Austin, Thomas R and Gardin, Julius M and Siggeirsdottir, Kristin and Tracy, Russell P and Gerszten, Robert E and Launer, Lenore J and Jennings, Lori L and Gudnason, Vilmundur and Sanders, Jason L and Odden, Michelle C} }