Total Insulinlike Growth Factor 1 and Insulinlike Growth Factor Binding Protein Levels, Functional Status, and Mortality in Older Adults.

OBJECTIVES: To assess the association between total insulinlike growth factor (IGF)-1, IGF binding protein-1 (IGFBP-1), and IGFBP-3 levels and functioning and mortality in older adults. DESIGN: Cohort study. SETTING/PARTICIPANTS: One thousand one hundred twenty-two individuals aged 65 and older without prior cardiovascular disease events participating in the Cardiovascular Health Study. MEASUREMENTS: Baseline fasting plasma levels of IGF-1, IGFBP-1, and IGFBP-3 (defined as tertiles, T1-T3) were examined in relationship to handgrip strength, time to walk 15 feet, development of new difficulties with activities of daily living (ADLs), and mortality. RESULTS: Higher IGFBP-1 predicted worse handgrip strength ( P-trendT1-T3<.01) and slower walking speed ( P-trendT1-T3=.03), lower IGF-1 had a borderline significant association with worse handgrip strength ( P-trendT1-T3=.06), and better grip strength was observed in the middle IGFBP-3 tertile than in the low or high tertiles ( P=.03). Adjusted for age, sex, and race, high IGFBP-1 predicted greater mortality ( P-trendT1-T3<.001, hazard ratio (HR)T3vsT1=1.48, 95% confidence interval (CI)=1.15–1.90); this association was borderline significant after additional confounder adjustment ( P-trendT1-T3=.05, HRT3vsT1=1.35, 95% CI=0.98–1.87). High IGFBP-1 was associated with greater risk of incident ADL difficulties after adjustment for age, sex, race, and other confounders ( P-trendT1-T3=.04, HRT3vsT1=1.40, CI=1.01–1.94). Neither IGF-1 nor IGFBP-3 level predicted mortality or incident ADL difficulties. CONCLUSION: In adults aged 65 and older, high IGFBP-1 levels were associated with greater risk of mortality and poorer functional ability, whereas IGF-1 and IGFBP-3 had little association with these outcomes. [ABSTRACT FROM AUTHOR]