“…From comparisons of two points of time to multiple-wave observations, the evidence has indicated that disability in older adults is not only a reversible condition but also a time-dependent process (Gill, Allore, Hardy, & Guo, 2006;Hardy & Gill, 2004;Seidel, Jagger, Brayne, Matthews, & Cfas, 2009). Patterns of disability change over time; in other words, the concept of the disability trajectory and identifying subgroups of older adults with different trajectories has gained recognition as ever more evidence supporting it is published in literatures (Chen, Mullan, et al, 2012;Chiu, Wray, & Ofstedal, 2011;Dodge, Du, Saxton, & Ganguli, 2006;Han et al, 2013;Hsu, 2009Hsu, , 2013Liang, Wang, et al, 2010;Liang, Xu, Bennett, Ye, & Quinones, 2010;Rajan et al, 2012;Taylor, 2010;Zimmer, Martin, Jones, & Nagin, 2014). The disability trajectory provides information on both the level of disability and the patterns of functional change over time.…”