Comprehensiveness vs Efficiency: A Cross-Sectional Analysis of the Association Between Allostatic Load and the Frailty Index Using the CLSA

The goal of this study was to investigate the associations between the frailty index (FI) and allostatic load (AL) to determine if allostatic load contains "key" biomarkers of frailty. If so, AL may offer a more concise health measure using only routine, administrative data. A cross-sectional study design was used to assess the relationships between AL and FI and compare these relationships with an extensively validated health measure, self-rated health. The data used for this study were obtained from the Canadian Longitudinal Study on Aging (CLSA) baseline comprehensive cohort (n = 26,367). Simple linear and logistic regression models were built to measure associations between AL and the FI, which was standardized for improved interpretability. Both indices associations with another validated health measure, self-rated health, were then compared. All increased levels of AL were associated with higher FI scores, consistent across both sexes. In fully adjusted models, an AL score of 4 was associated with a 0.504 SD and 0.500 SD increase in FI in both male and female individuals, respectively (99% CIM, 0.379-0.496; 99% CIF, 0.357-0.643). Both increased FI and AL were also associated with increased odds of reporting poor or fair health. These results suggest that AL and the FI are related, and that allostatic load may indeed contain "key" biomarkers of frailty. Given this, it is reasonable to suggest that AL could be used in at least an equivalent capacity to the FI currently and may represent a more practical and efficient measure of health and health risk.