Using grip strength to compute physical health-adjusted old age dependency ratios

The standard approach for comparing the potential challenges of population aging across countries based on conventional old-age dependency ratios (OADR) does not account for cross-population differences in health, functional capacity or disability, despite their importance for labor force participation and dependency more broadly. We investigate how OADRs observed across selected low-, middle-, and high-income countries change if population differences in physical health measured by hand-grip strength are accounted for. Specifically, we propose and calculate an adjusted measure of the OADR based on hand-grip strength, which serves as an objective indicator of muscle function and has been shown to predict future morbidity, disability and mortality. We show that adjusting the OADR for differences in hand-grip strength results in substantial changes in country rankings by OADR compared to a ranking based on the conventional OADR definition. Accounting for cross-population differences in hand-grip strength, the estimated OADRs for low- and middle-income countries tend to increase compared to the conventional OADR approach based on age only, whereas the estimated OADRs in high-income countries decline substantially relative to the standard approach. Since hand-grip strength is an important prerequisite for maintaining functional capacity and productivity and preventing disability –especially in economies in low-income settings– our grip-strength-adjusted OADRs clearly show that population aging is not just a challenge in high-income countries but also an important concern for economies in the developing world.