TY - JOUR
T1 - Association of a modified physiologic index with mortality and incident disability
T2 - The health, aging, and body composition study
AU - Sanders, Jason L.
AU - Boudreau, Robert M.
AU - Penninx, Brenda W.
AU - Simonsick, Eleanor M.
AU - Kritchevsky, Stephen B.
AU - Satterfield, Suzanne
AU - Harris, Tamara B.
AU - Bauer, Douglas C.
AU - Newman, Anne B.
N1 - Funding Information:
This research was supported by National Institute on Aging (NIA) Contracts N01-AG-6-2101; N01-AG-6-2103; N01-AG-6-2106; NIA grant R01-AG028050, and NINR grant R01-NR012459. This research was supported in part by the Intramural Research Program of the NIH, National Institute on Aging. JLS is supported by a National Research Service Award from the National Institute on Aging (1F30-AG038093-01).
PY - 2012/12
Y1 - 2012/12
N2 - Background.Indexes constructed from components may identify individuals who age well across systems. We studied the associations of a Modified Physiologic Index (systolic blood pressure, forced vital capacity, Digit Symbol Substitution Test score, serum cystatin-C, serum fasting glucose) with mortality and incident disability.Methods.Data are from the Health, Aging, and Body Composition study on 2,737 persons (51.2% women, 40.3% black) aged 70-79 years at baseline and followed on average 9.3 (2.9) years. Components were graded 0 (healthiest), 1 (middle), or 2 (unhealthiest) by tertile or clinical cutpoints and summed to calculate a continuous index score (range 0-10). We used multivariate Cox proportional hazards regression to calculate risk of death or disability and determined accuracy predicting death using the area under the curve.Results.Mortality was 19% greater per index unit (p <. 05). Those with highest index scores (scores 7-10) had 3.53-fold greater mortality than those with lowest scores (scores 0-2). The unadjusted index (c-statistic = 0.656, 95% CI 0.636-0.677, p <. 0001) predicted death better than age (c-statistic = 0.591, 95% CI 0.568-0.613, p <. 0001; for comparison, p <. 0001). The index attenuated the age association with mortality by 33%. A model including age and the index did not predict death better than the index alone (c-statistic = 0.671). Prediction was improved with the addition of other markers of health (c-statistic = 0.710, 95% CI 0.689-0.730). The index was associated with incident disability (adjusted hazard ratio per index unit = 1.04, 95% CI 1.01-1.07).Conclusions.A simple index of available physiologic measurements was associated with mortality and incident disability and may prove useful for identifying persons who age well across systems.
AB - Background.Indexes constructed from components may identify individuals who age well across systems. We studied the associations of a Modified Physiologic Index (systolic blood pressure, forced vital capacity, Digit Symbol Substitution Test score, serum cystatin-C, serum fasting glucose) with mortality and incident disability.Methods.Data are from the Health, Aging, and Body Composition study on 2,737 persons (51.2% women, 40.3% black) aged 70-79 years at baseline and followed on average 9.3 (2.9) years. Components were graded 0 (healthiest), 1 (middle), or 2 (unhealthiest) by tertile or clinical cutpoints and summed to calculate a continuous index score (range 0-10). We used multivariate Cox proportional hazards regression to calculate risk of death or disability and determined accuracy predicting death using the area under the curve.Results.Mortality was 19% greater per index unit (p <. 05). Those with highest index scores (scores 7-10) had 3.53-fold greater mortality than those with lowest scores (scores 0-2). The unadjusted index (c-statistic = 0.656, 95% CI 0.636-0.677, p <. 0001) predicted death better than age (c-statistic = 0.591, 95% CI 0.568-0.613, p <. 0001; for comparison, p <. 0001). The index attenuated the age association with mortality by 33%. A model including age and the index did not predict death better than the index alone (c-statistic = 0.671). Prediction was improved with the addition of other markers of health (c-statistic = 0.710, 95% CI 0.689-0.730). The index was associated with incident disability (adjusted hazard ratio per index unit = 1.04, 95% CI 1.01-1.07).Conclusions.A simple index of available physiologic measurements was associated with mortality and incident disability and may prove useful for identifying persons who age well across systems.
KW - Aging
KW - Disability
KW - Index
KW - Longevity
KW - Mortality
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UR - http://www.scopus.com/inward/citedby.url?scp=84869424249&partnerID=8YFLogxK
U2 - 10.1093/gerona/gls123
DO - 10.1093/gerona/gls123
M3 - Article
C2 - 22546961
AN - SCOPUS:84869424249
SN - 1079-5006
VL - 67
SP - 1439
EP - 1446
JO - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
JF - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
IS - 12
ER -