Mobility, the ability to move, walk or climb easily and freely1 is essential for independent living and healthy aging. Loss of mobility is an indicator of physical decline,2, 3, 4 an early sign of physical disability,1 and the third leading cause of death.2,5 Loss of mobility affects about 27 % of older adults worldwide.1 Many older adults need mobility devices such as canes and walkers to compensate for the loss of mobility.6 Canes and walkers as low-tech mobility devices are seemingly mundane but have great potential to enable mobility, reduce injury, prevent functional decline, maintain independent living, and improve quality of life.7, 8, 9 However, recent advances in smart mobility devices10 have made those low-tech mobility devices overlooked. Moreover, older adults are shown to lag in adopting smart mobility devices11,12 due to high cost, low availability, and low readiness for daily use.13,14 Thus, the World Health Organization has recommended low-tech devices (referring to mobility devices throughout) as simple, cheap, and vital solutions for healthy aging.15,16

The rapid growth of the aging population has led to an unprecedented need for mobility devices.16 Ensuring equitable access and efficient use of mobility devices is a national priority in China. However, the mobility-device-use-associated disparity is a major global public health challenge.15,17,18 Worldwide, about one billion people who need the devices lack access or fail to use the devices.14,15 The prevalence of mobility device use among older Chinese adults is unclear. A recent study on older Chinese adults reported a lower prevalence of device use (10.9 %)19 compared to that in U.S. older adults (24 %).6 However, participants in this study were not representative of Chinese older adults. More research is needed to understand the existence and extent of disparities in the use of mobility devices among Chinese old adults.

Age and gender can be two important demographic factors affecting mobility device use considering potential functional declines with older age2 and gender- or equipment-related stereotypes.4,16 Specifically, men, including old men are often viewed as strong and self-reliant,20 and using mobility devices may make them feel vulnerable to loss of independence and marginalized,21 which can discourage the use of devices. Falling can be another important reason for older adults to use mobility devices.6,22,23 Although using mobility devices is considered a practical solution to maintain mobility and prevent falls, only 26 % of older adults who have had falls actually use mobility devices.9,23,24 A recent study suggests that falls may not be associated with mobility device use.6 Inconclusive findings confirm more research is needed in this field.

Age- and gender-associated disparities in mobility device use are highlighted in the previous studies.4,6 However, few studies have examined the joint effects of age and gender on the use of mobility devices and how falls can contribute to device use among older adults. According to the feminist intersectionality framework which has been widely used to understand gender inequities and social determinants of health,20,25 social identities, for example, old age interacting with gender can impose a synergistic effect on a person's health risks and social disparities.20 Health and social disparities cannot be fully captured by examining social identities of age and gender separately, given that they are interconnected.25 Using the intersectional lens to better understand mobility device use is crucial yet understudied, and results may help inform interventions and guidelines to promote mobility devices use among older adults.

Guided by the feminist intersectionality framework,20 using nationally representative data, we sought to explore 1) the prevalence of mobility device use among Chinese older adults who needed mobility devices (defined by the mobility difficulties), 2) whether device use disparities with the intersection of age and gender present over time, and 3) whether falls further explain the use disparities in addition to the joint effect of age and gender over time.