Toward a positive aging phenotype for older women: observations from the women's health initiative.

BACKGROUND To develop a positive aging phenotype, we undertook analyses to describe multiple dimensions of positive aging and their relationships to one another in women 65 years of age and older and evaluate the performance of individual indicators and composite factors of this phenotype as predictors of time to death, years of healthy living, and years of independent living. METHODS Data from Women's Health Initiative clinical trial and observational study participants ages 65 years and older at baseline, including follow-up observations up to 8 years later, were analyzed using descriptive statistics and principal components analysis to identify the factor structure of a positive aging phenotype. The factors were used to predict time to death, years of healthy living (without hospitalization or diagnosis of a serious health condition), and years of independent living (without nursing home admission or use of special services). RESULTS We identified a multidimensional phenotype of positive aging that included two factors: Physical-Social Functioning and Emotional Functioning. Both factors were predictive of each of the outcomes, but Physical-Social Functioning was the strongest predictor. Each standard deviation of increase in Physical-Social Functioning was accompanied by a 23.7% reduction in mortality risk, a 19.4% reduction in risk of major health conditions or hospitalizations, and a 26.3% reduction in risk of dependent living. CONCLUSIONS Physical-Social Functioning and Emotional Functioning constitute important components of a positive aging phenotype. Physical-Social Functioning was the strongest predictor of outcomes related to positive aging, including years of healthy living, years of independent living, and time to mortality.